The Impact of Dysarthria on Everyday Communication Following Traumatic Brain Injury

Yiting Emily Guo (200392236)

A thesis submitted as part of the requirements 
for the degree of
 Bachelor of Applied Science Honours (Speech Pathology)
School of Communication Sciences and Disorders
Faculty of Health Sciences
University of Sydney
1st December 2006

None of the work in this thesis has been submitted for any form of credit to any other university or institution. 

This project topic and design was developed within a series of research projects undertaken by Dr Leanne Togher.  The literature review, collection of some of the data, data analyses and writing of the thesis was carried out by Yiting Emily Guo with appropriate help and supervision. 

Yiting Emily Guo

The impact of dysarthria on everyday communication after traumatic brain injury

YITING EMILY GUO & LEANNE TOGHER

School of Communication Sciences and Disorders, Faculty of Health Sciences, University of Sydney, New South Wales, Australia

Abstract

Primary objective: To compare the everyday communication of individuals with mild and moderate dysarthria and concomitant cognitive-communication impairments following traumatic brain injury (TBI) 

Methods and procedures: Five participants with mild dysarthria and five with moderate dysarthria following TBI were recorded during telephone service enquiries with bus timetable call centre operators. Transcripts were analysed using exchange structure analysis derived from systemic functional linguistics. Listener comfort ratings were collected using a novel equal appearing interval scale to measure how comfortable people would feel interacting with the participants. 

Main outcomes and results: Participants with moderate dysarthria were not necessarily penalised for having poorer intelligibility during bus timetable service encounters. While participants with moderate dysarthria were given poorer listener comfort ratings, this did not affect the way information was exchanged with bus timetable call centre operators. These findings were attributed to the powerful interactional role of TBI participants as customers, the amount of disability awareness training and experience held by call centre operators and the highly structured nature of bus timetable service enquiries. Listener comfort ratings could be predicted with moderate accuracy from intelligibility scores. 

Conclusions: Service encounters where individuals with TBI are placed in a powerful interactional role of customer may be functional generalization tasks. Training and education of service providers may also impact on the communicative effectiveness of individuals with TBI.

Introduction 
Dysarthria, a group of speech disorders resulting from disturbances to the speech musculature due to neurological damage [1,2], is one of the most unrelenting ________________________________________________________________________
Correspondence: Leanne Togher, PhD, S Block, School of Communication Sciences and Disorders, The University of Sydney, PO Box 170, East St., Lidcombe, NSW Australia 1825. Email: l.togher@fhs.usyd.edu.au
consequences of traumatic brain injury (TBI) [3], occurring in approximately one-third of individuals with TBI five years post-injury [4]. Since the incidence of TBI for both males and females peaks between the ages of 15 and 24 [5], the presence of a dysarthria has important implications for the long term quality of life of individuals with TBI. This is compounded by the fact that many individuals with TBI have concurrent cognitive-communication difficulties [4,6]. 
Standardised perceptual measures like the Assessment of Intelligibility of Dysarthric Speech (ASSIDS) [7]  and the Frenchay Dysarthria Assessment (FDA) [8] have been reported to be most frequently used in assessing dysarthria after TBI [9]. In general, these tests provide valuable information as, by virtue of standardization, reliability is taken into consideration. Standardised tests are also useful in test-retest situations for tracking outcomes of intervention.  
Despite the merits of standardised assessments, their validity has been questioned, based on the criticism that standardised assessments fail to reflect everyday performance and have little relevance to real contexts [10]. For instance, intelligibility measures obtained from the ASSIDS are scored on single word and sentence production tests, and are therefore removed from communicative context, event or purpose [11]. Scores on the ASSIDS may underestimate the person’s ability to communicate in everyday situations where situational and contextual information are available to listeners [11]. It may thus be inappropriate to use standardised tests alone for evaluating everyday communication, since ‘real-world’ or routine communicative situations cannot be encompassed [12].
A functional approach has been increasingly used in the TBI population and this correlates to the ‘activity’ and ‘participation’ levels under the World Health Organization’s Classification of Functioning, Disability and Health (ICF) [13]. Functional communication includes the integration of cognitive, linguistic and speech articulatory abilities that enable an individual to communicate in everyday situations [12]. The relevance of looking at everyday communication is particularly justified considering the perseverance of the associated communication disorders, the age of individuals with TBI and the need to justify the cost of rehabilitation using functional outcomes [14]. By examining dysarthria in everyday communication, the clinician can learn more about what aids communicative effectiveness and draw on techniques beyond that of improving acoustics and phonology [15]. Therefore, the relationship between analyses of everyday communication and standardised dysarthria tests was explored in this paper. 

Discourse analysis and traumatic brain injury
Discourse analysis is one of the ways in which the adequacy of everyday communication may be assessed [12]. The use of discourse analysis has been recognised to be increasingly relevant for individuals with TBI [16,17]. Among the advantages of using discourse analysis is the opportunity it offers to view an individual’s language in context and to judge the effectiveness of communication in more complex activities [18]. Discourse measures may also provide insight to the social integration and quality of life of individuals with TBI [19]. This provides a means of measuring functional outcomes of speech pathology interventions, so that client satisfaction is ensured and claims for funding can be justified in terms that insurers and health service providers can understand [10]. 
Systemic functional linguistics (SFL) is a framework that links specific language structures to the context in which they occur [20]. Discourse analyses based upon SFL can thus be applied to various speaking situations and communication partners. This enables the examination of how individuals with TBI communicate with others in their community and the role of communication partners in various interactions. SFL may thus aid the clinician in making decisions about how to direct treatment efforts in relevant everyday contexts [10].
Service encounters, everyday interactions where either goods or information are exchanged, may be a relevant everyday context for individuals with TBI. This is particularly so, since getting basic help, making enquiries, speaking clearly and using the telephone are among the communicative activities rated to be highly important for people with TBI [21]. Service encounters may occur either face-to-face or over the telephone, and are considered practical generalization tasks for individuals with TBI in rehabilitation [22,23]. The ability to negotiate service encounters may also lead to greater independence in living and thereby, greater community access and integration [24]. Therefore, the study of how individuals with TBI communicate in service encounters is warranted. Service encounters have been argued to be best analysed using systemic functional analyses [25]. 
Exchange structure analysis [26,27] is an analysis from the SFL framework that has been used with the TBI population [28,29].  This analysis is concerned with who has the information in an interaction and how this information is transferred between communication partners. Togher et al. [28] examined telephone interactions where five participants with TBI and five matched control participants were asked to request for specific information from a range of communication partners including their mothers, therapists, police officers and call centre operators. Participants with TBI were differentiated from control participants on a number of measures of exchange structure. For instance, participants with TBI were given less information and were also asked for less information overall. The results of this study, even with its low statistical power, have important implications for family and community education regarding communication with individuals with TBI. 
One of the unanswered questions from Togher et al. [28] was whether altered responses from communication partners of participants with TBI when compared to control participants was due to perceived cognitive-communication difficulties or the result of a response to mildly impaired intelligibility or prosodic impairments. All participants with TBI were reported to have some evidence of impaired prosody as rated by two independent speech pathologists on the Pragmatic Protocol [30]. Investigation of this question was beyond the scope of this study and remains unanswered.  
Thus far, there has been a dearth of research examining the effect of acquired dysarthria on the discourse of individuals with TBI in their everyday interactions. This is despite clinical observations that difficulties in discourse tasks like conversation are ubiquitous in speakers with dysarthria [31]. In a study examining first encounter conversational discourse in five elderly participants with dysarthria following stroke [31], it was found that participants with dysarthria contributed fewer major conversational turns compared to the 19 elderly control participants with no brain damage. The participants with dysarthria also had shorter conversational turns and more pauses before turns. In this study, dysarthria had a significantly negative impact on conversational discourse. 
A drawback of the study by Comrie et al. [31], however, is that only one aspect of conversation, that is, turn taking, was examined. The conversation used was with the researcher, an unfamiliar conversational partner, a situation which may not be indicative of everyday communication. The participants selected for this study also had no other communication disorders apart from dysarthria. It is uncertain, therefore if the results of this study are applicable to individuals with dysarthria following TBI, who often have co-morbid cognitive-communication difficulties as well. The stroke participants also differed in demographic profile from the typical cohort of individuals with TBI in terms of age. Clearly, more research is warranted in studying the discourse of people with dysarthria. This includes the study of discourse in different speaking situations, with different communication partners, in people with different aetiologies of dysarthria and the inclusion of a wider range of analyses.
The effects of dysarthria on everyday interactions can be measured in a range of ways. Dysarthria may impact on the way information is exchanged, and may result in communication breakdowns. Therefore, an examination of these issues using exchange structure analysis is warranted. Another approach is to examine how listeners perceive the person with dysarthria, as this may result in modifications to their responding. It also would provide a measure of social validity [32]. 

Perceptual ratings of listener comfort
Listener comfort is particularly relevant to the study of interactions given the negative reactions reported towards people with dysarthria [33]. For example,  adolescent and adult listeners judged children with dysarthria to have significantly more negative personality and physical traits than children without dysarthria based on taped recordings of spoken speech [33,34]. Previous studies in dysarthria have examined listener judgements of speech acceptability and naturalness [35-39], where a focus has been placed on speaker attributes like ‘speaking ability’ [37-39]. For instance, the relationship between intelligibility and acceptability judgements has been of particular interest [35,37-39]. Whitehill et al. [35] found intelligibility to be a strong predictor of acceptability judgements. However, intelligibility was not always found to correlate with acceptability judgements [37-39]. 
The concept of listener comfort may have potential clinical relevance as it depicts what it would be like to interact with a speaker [32]. This includes what listeners bring to the interaction as well as speaker attributes [40]. However, the concept of listener comfort has thus far only been applied in the field of stuttering [32,40,41] and synthesised speech in dysarthria/augmentative alternative communication [42]. In this later study, listeners tended to be more comfortable with listening to synthesised speech than dysarthric speech over the telephone. Hence, this study examined the use of listener comfort with individuals who have mild and moderate dysarthria following TBI. It is hypothesised that while speaker attributes like intelligibility will play a role in determining listener comfort, other factors relating to listeners like ‘effort listening’, that is, the amount of effort needed for listening, [41] will also be important. 
Therefore, the aims of this study were to compare the communication of two groups of individuals with mild and moderate dysarthria following TBI during telephone interactions and on standardised intelligibility tests. The study compared the relationship between standardised intelligibility test scores with measures of everyday discourse from exchange structure analysis. It was hypothesised that speakers with reduced intelligibility scores following TBI would have greater difficulty obtaining information during a service encounter, as measured by exchange structure analysis.  The study also explored how comfortable unfamiliar listeners felt about the speech of individuals who have mild and moderate dysarthria following TBI.  Specifically, the relationship between listener comfort ratings and measures of everyday discourse were examined.  It was hypothesised that those speakers who were scored as uncomfortable to interact with would have increased difficulties obtaining information, as measured by exchange structure analysis. Finally, as the listener comfort ratings had not been previously used with a dysarthric sample, they were correlated with standardised intelligibility test scores to examine their validity.
This resulted in the following questions:

1.	 Is there a relationship between standardised intelligibility scores and exchange structure measures?
2.	 Is there a relationship between perceptual ratings of listener comfort and exchange structure measures?
3.	 Is there a relationship between standardised intelligibility scores and perceptual ratings of listener comfort?
Method
Participants	
Participants were ten adults with traumatic brain injury recruited from the inpatient and community caseload at the Liverpool Hospital Brain Injury Rehabilitation Unit. The participants ranged in age from 17 to 46 years (mean = 27 years). At the time of their injuries, nine participants had been employed and one had been studying. One participant was employed at the time of the study. All participants had sustained a very severe blunt closed head injury (i.e. post-traumatic amnesia > 24 hours) [43]. Participants were divided into two groups, A (Moderate dysarthria) and B (Mild dysarthria), according to the presence and severity of dysarthria, as measured on the Assessment of Intelligibility of Dysarthric Speech (ASSIDS) [7]. Participants in both groups were matched on age (t = 0.25, p = 0.81), time since injury (t = 0.56, p = 0.59) and period of post-traumatic amnesia (t = -0.12, p = 0.90). Please see Table 1 for further details.

Table 1.  Demographic and clinical details of participants
Participant no.	Age (years)	Premorbid occupation	Time since injury (years)	Period of post-traumatic amnesia (months)	Nature of accident	
Group A (Moderate dysarthria)				
A-1	17	Hairdressing apprentice	1	7	Driver in motor vehicle accident	
A-2	21	Hospitality worker	0.4	2	Fall from bicycle	
A-3	37	Shop assistant	18	4	Pedestrian in motor vehicle accident	
A-4	46	Photographic printing	14	4.7	Pedestrian in motor vehicle accident	
A-5	19	Student	3	1.5	Gunshot	

Group B (Mild dysarthria)				
B-1	28	Cleaner	2	> 6	Fall from skateboard	
B-2	35	Carpenter	13	6	Driver in motor vehicle accident	
B-3	22	Labourer, Cook	0.2	4.5	Assault	
B-4	27	Carpenter	4	3	Driver in motor vehicle accident	
B-5	20	Kitchen hand	1	3.2	Assault	

Participants engaged in a 15 minute videotaped conversation with a research assistant. The conversation was then rated by two independent speech pathologists using the Pragmatic Protocol [30]. All participants were rated as being inappropriate by both speech pathologists. 
In addition, all participants fulfilled the following criteria, they
i)	had a cognitive-communication disorder on the Scales of Cognitive Ability following Traumatic Brain Injury (SCATBI) [44], with a severity score in the mild-moderate range
ii)	were not in a state of post traumatic amnesia (PTA), a confused state of varying length which directly follows the occurrence of the head injury
iii)	were cognitively able to complete the research tasks and have an adequate concentration and attention span
iv)	did not exhibit aphasia, a specific language impairment resulting in impaired expression and comprehension of basic language functions
v)	agreed to participate in the study and provided informed consent
 
The study was approved by the University of Sydney Human Research Ethics Committee, and the Sydney South West Area Health Service Human Research Ethics Committee. 

Standardised assessments
All participants with TBI underwent two standardised tests. One of these was the Scales of Cognitive Ability following Traumatic Brain Injury (SCATBI) [44], which was used to determine the eligibility of participants for the study. The SCATBI consists of five subtests which are designed to measure cognitive/linguistic processes which may be affected following TBI. Three of the subtests, Organization, Recall and Reasoning, were administered to all participants. Results of each scale are expressed using a standard score (mean of 100 and standard deviation of 15), and scores from the latter two subtests are used to derive a total score.
The other standardised assessment was the Assessment of Intelligibility of Dysarthric Speech (ASSIDS) [7]. This was used to place the participants into two groups.  If participants scored between 65-85% intelligible on the Words and Sentences sub-tests of the ASSIDS, they were placed in Group A (Moderate dysarthria). If participants had mild dysarthria/prosodic problems but good intelligibility (>85% intelligible), they were placed in Group B (Mild dysarthria).
The results of the standardised assessments are found in Table 2. There was no significant differences between groups A and B on SCATBI total scores (t = -0.19, p = 0.86). 

Table 2.  Results of standardised assessments
Participant no.	SCATBI total 	Organization	Recall	Reasoning	ASSIDS total (%)	
Group A (Moderate dysarthria)	
A-1	102	119	95	97	73.0	
A-2	97	98	91	86	71.0	
A-3	111	129	96	101	67.4	
A-4	94	95	98	107	73.0	
A-5	90	97	106	91	70.2	

Group B (Mild dysarthria)				
B-1	102	119	103	100	86.0	
B-2	98	115	101	96	86.3	
B-3	97	115	98	96	86.0	
B-4	94	129	84	92	91.3	
B-5	107	129	87	96	89.9	
   
Telephone interactions
	All participants were asked to make a telephone call to a call centre operator from the bus timetable information service. The calls were designed to be enquiries for specific information and a scenario set up prior to each interaction to facilitate ecological validity. This involved finding out information about the bus they would need to catch for a group outing to a shopping centre in Sydney. In addition to the bus route, participants were required to find out the time the bus would leave. All telephone conversations were recorded using audio tapes and transcribed verbatim. All participants were informed that they were being recorded.  
The telephone conversational samples collected were analysed using exchange structure analysis (ESA) derived from the framework of Systemic Functional Linguistics  (SFL) [20]. All telephone interactions were divided into exchanges with the use of intonational cues to assist with decisions regarding exchange boundaries. Each exchange is composed of a sequence of moves, which are units of information that form the basis of the exchange structure analysis [20]. 

Exchange structure analysis
Exchange structure analysis examines interactions in terms of information giving, information requesting and receiving, and the amount of negotiation needed for messages to be conveyed [26,27]. In this analysis, the provider of information (i.e. primary knower) is noted by the abbreviation K1 and the recipient of information (i.e. secondary knower) K2. Example 1 shows an exchange consisting of a request for information (K2) by the call centre operator and provision of information (K1) by the participant A-1. These synoptic moves are denoted by brackets.

Example 1: A-1 = TBI participant; C = Call centre operator (moves 17-18)
No.	Move	Speaker	Utterance	
17	K2	C	and you are going to where?	
18	K1	A-1	Macquarie shopping centre X at Ryde	
K2 = request for information; K1 = provision of information; X = unintelligible 

However, exchanges of information are rarely this straightforward. Therefore, dynamic moves are often used to negotiate and facilitate exchanges. Dynamic moves may occur through active means like clarification or checking, or through providing feedback that information has been conveyed successfully [28]. Example 2 consists of an information giving exchange. In this example, the call centre operator provided the information (K1) and participant A-1 received the information (K2f). This move is denoted as K2f because it is a follow-up move which indicated the end of the exchange. Dynamic moves of replay request (rprq), and response to replay request (rrprq) were used as some information was missed. Back-channelling (bch) moves were also used, providing feedback that information had been conveyed successfully in the telephone call. These dynamic moves are marked by arrows. See Appendix 1 for the various types of dynamic moves.

Example 2:  A-1 = TBI participant; C = Call centre operator (moves 25-31)
No.	Move	Speaker	Utterance	
25	K1	C	Ok there would be a train at twelve twenty four from Padstow	
26	rprq	A-1	Where sorry?	
27	rrprq	C	Twelve twenty four   twenty four minutes past [twelve	
28	bch	A-1	 [OK yes	
29	K1	C	and that would take you to Redfern station	
28	bch	A-1	Yes	
30	K1	C	arriving at twelve forty nine	
31	K2f	A-1	OK then	
K1 = provision of information; rprq = replay request; rrprq = response to replay request; bch = back-channel; K2f = follow up to information provided

Apart from information exchanges, action exchanges often occur during interactions. These consist of a person requesting for an action to be performed (A2) and the person performing the action (A1). Example 3 shows an action exchange (moves 17 and 18) occurring within an information exchange. In this example, participant B-5 requested for a pause (A2) while the call centre operator was providing information (K1). The action of waiting was then carried out by the call centre operator (A1). Dynamic moves of back-channelling (bch) and replay request (rprq) were also used to facilitate the exchange. 

Example 3:  B-5 = TBI participant; C = Call centre operator (moves 12-19)
No.	Move	Speaker	Utterance	
12	K1	C	Alright from Strathfield station	
13	bch	B-5	yep	
14	K1	C	you can take a train	
15	bch	B-5	yep	
16	K1	C	at 11.29	
17	A2	B-5	hang I just ah I just gotta write it down	
18	A1	C	ok	
19	rprq	B-5	alright a train what time?	
K1 = provision of information; bch = back-channel; A2 = request for action; A1 = provision of action; 
rprq = replay request 

The exchange structure analysis was chosen as it is concerned with who is in charge of the information during an interaction, and how this information is transferred. It was hypothesised that participants with moderate dysarthria (Group A) would differ from participants with mild dysarthria (Group B) in their use of K1, K2 and dynamic moves. 

Perceptual rating of listener comfort
Perceptual ratings of listener comfort were collected to investigate if there was a relationship with participants’ intelligibility and/or participants’ use of exchange structure moves. 

Listeners
Listeners were 12 Year One students (11 female, one male) enrolled in an undergraduate course of speech pathology between 17 and 25 years of age. They were considered to be naïve listeners with no prior experience to dysarthric speech. All listeners passed a hearing screening test for 1000, 2000, and 4000 Hz at 20 dB HL. All listeners received a certificate for participation in the research project.

Preparation of perceptual stimuli
The first 30 seconds of each telephone call with the bus timetable call centre operators was extracted and digitised into files using Adobe Audition 1.5. This resulted in ten files in total. The first 30 seconds were chosen as it is during this time that first impressions occur during telephone interactions with unfamiliar listeners [28].

Auditory-perceptual procedure
A ten minute training session was held prior to the listening task. This included definitions of terms and introduction to a 7-point equal appearing interval (EAI) scale. Verbal and written instructions were provided during the training session. 
Listener comfort was defined as ‘How comfortable would you feel interacting with this person?’ Listeners represented ‘very uncomfortable’ as ‘1’ and ‘7’ represented ‘very comfortable’ speech. Two speech samples that represented ‘1’ and ‘7’ respectively were played. An anchored EAI scale was used to improve reliability of the ratings obtained [45]. A trial of three speech samples, which were not included in the results, was also conducted. The listeners were permitted to ask questions during the trial period.	
Listening tasks were conducted individually in a quiet room. The stimuli were randomly presented through headphones adjusted to the most comfortable level via a notebook computer. The listening task took about half an hour for each listener.

Reliability

Exchange structure analysis	
	Intra-rater and inter-rater agreement were established on 20% of the data. Inter-rater agreement was completed between the researcher and an independent speech pathologist with previous knowledge of systemic functional linguistic analyses. This was based on the point-by-point agreement of the types of move and the division of transcripts into exchanges. Agreement was considered to have been reached only when there was agreement to both the type of move and the division of exchange. Intra-rater agreement averaged 94% and inter-rater agreement averaged 89%, which fell within the minimum acceptable level of ≥ 80% [46].

Perceptual rating of listener comfort
Intra-rater reliability and agreement was based on repeating the samples for three randomly selected speakers (30% of speakers). The values assigned by each listener were compared to values assigned to the repeated speaker samples. The percent agreement was calculated by counting the number of comparisons in which the assigned scale value did not differ by more than +/- 1 scale value, dividing this number by three for each speaker, and multiplying by 100. The mean intra-rater agreement was 81.1% (n = 12) and intra-rater agreement ranged from 33.3% (n = 1) to 100% (n = 8). Therefore, intra-rater agreement was high relative to a 7-point scale, suggesting that most raters maintained internal consistency in determining how comfortable they felt listening to the speakers.
Interrater agreement was measured to determine the extent to which all listeners assign the same rating to a given sample. This was achieved by comparing the value assigned by each listener to the value assigned by every other listener. 77.0% of the ratings were assigned to +/- 1 scale value (range = 57.3% - 89.1%). This suggested that most listeners provided similar ratings for each speaker.
Interrater reliability was measured using the intraclass correlation (ICC), model 2 [47]. The group reliability coefficient was 0.96 (range = 0.91-0.99) and highly acceptable. The individual rater reliability coefficient was lower at 0.66 (range = 0.45-0.87), but was still within the fair to good range specified by Fleiss [48].

Results 

Telephone interactions: exchange structure 
	The total time, total number of exchanges, and total number of moves for each participant are displayed in Table 3. No statistically significant differences were found in the total time (U = 10.00, p = 0.69, r = -0.17), total number of exchanges (U = 8.50, p = 0.42, r = -0.28) and total number of moves (U = 10.00, p = 0.69, r = -0.17) for participants in both groups.

Table 3.  Total time, total number of exchanges and total number of moves in exchange structure analysis
Participant no.	Total time (minutes)	Total exchanges	Total moves	
Group A (Moderate dysarthria)	
A-1	3.10	8	47	
A-2	2.58	6	64	
A-3	1.50	5	37	
A-4	1.52	4	37	
A-5	1.42	5	42	

Group B (Mild dysarthria)	
B-1	1.92	6	39	
B-2	1.23	5	33	
B-3	2.13	8	63	
B-4	2.75	8	43	
B-5	1.25	5	37	

After scoring all transcripts according to exchange structure moves, three types of moves were compared. This included K1 moves per minute which is considered as the rate of information giving within interactions, K2 moves per minute which is interpreted as the rate at which interactants are requesting the information, and dynamic moves per minute which is the rate of negotiating and tracking of information which is needed for information exchange to be successful.
	The mean frequency of K1 moves per minute, K2 moves per minute and dynamic moves per minute by participants with TBI and call centre operators in Groups A (Moderate dysarthria) and B (Mild dysarthria) are found in Tables 4 and 5.

Table 4.  Exchange structure moves by participants with TBI
Group	K1 moves/minute	K2 moves/minute	Dynamic moves/minute	
A (n = 5)
	Mean = 1.57
Range = 0.67-2.82 
S.D. = 0.89
	Mean = 2.74
Range = 0.65-5.33
S.D. = 1.73	Mean = 5.04
Range = 3.33-7.36
S.D. = 1.76
	
B (n=5)
	Mean = 1.74
Range = 0.81-2.40 
S.D. = 0.74	Mean = 2.25
Range = 0.52-4.06
S.D. = 1.35	Mean = 4.43
Range = 3.13-6.09
S.D. = 1.24	
Group A = Moderate dysarthria	Group B = Mild dysarthria

Table 5.  Exchange structure moves by call centre operators
Group	K1 moves/minute	K2 moves/minute	Dynamic moves/minute	
A (n=5)	Mean = 3.64
Range = 2.90-4.67
S.D. = 0.77
	Mean = 2.33
Range = 1.29-3.53
S.D. = 1.02	Mean = 4.03
Range = 1.94-6.58
S.D. = 2.10	
B (n=5)	Mean = 3.68
Range = 2.18-4.80
S.D. = 1.03	Mean = 1.63
Range = 0.81-2.81
S.D. = 0.91	Mean = 3.23
Range = 1.45-5.68
S.D. = 1.64	
Group A = Moderate dysarthria	Group B = Mild dysarthria

Relationship between intelligibility and exchange structure
The effect of intelligibility on the frequency of exchange structure moves was examined by applying the Mann-Whitney U test. No statistically significant differences were found in the use of K1 moves per minute (U = 9.00, p = 0.55, r = -0.23), K2 moves per minute (U = 11.00, p = 0.84, r = -0.10) or dynamic moves per minute (U = 9.00, p = 0.55, r = -0.23) by participants with moderate dysarthria (Group A) compared to those with mild dysarthria (Group B). There was no significant differences in the use of K1 moves per minute (U = 12.00, p = 1.00, r = -0.03), K2 moves per minute (U = 6.00, p = 0.22, r = -0.43) or dynamic moves per minute (U = 10.00, p = 0.69, r = -0.17) by call centre operators in both groups.  
Spearman’s rank order correlations were used to examine the relationship between ASSIDS scores and exchange structure moves. No significant correlation was found between all exchange structure moves and total ASSIDS, word intelligibility and sentence intelligibility scores (Table 6).

Table 6: Spearman’s rank order correlations between intelligibility scores and exchange structure moves
Exchange structure element	ASSIDS total		Word intelligibility		Sentence intelligibility	
	rs		rs		rs	
Moves by TBI participants									
     K1 moves/minute	 0.20		 0.36		 0.00	
     K2 moves/minute	-0.20		-0.24		-0.07	
     Dynamic moves/minute	-0.27		-0.31		-0.15	

Moves by call centre operators									
     K1 moves/minute	-0.21		-0.14		 0.01	
     K2 moves/minute	-0.45		-0.31		-0.49	
     Dynamic moves/minute	-0.26		-0.30		-0.16	

Quality of telephone interactions
While no statistical differences were found in the exchange structure moves used by participants and call centre operators in groups A (Moderate dysarthria) and B (Mild dysarthria), qualitative differences were found in the telephone interactions. For instance, three participants in Group A (Moderate dysarthria) and two participants in Group B (Mild dysarthria) made incomplete requests for information. These participants correctly enquired about how to get from Strathfield Station to Macquarie Shopping Centre but did not specify that they wanted to travel by bus. This led to the call centre operators providing train travel information in two instances for Group A (Moderate dysarthria) and both instances in Group B (Mild dysarthria). Example 4 demonstrates one of these incomplete requests for information.

Example 4:  B-4 = TBI participant; C = Call centre operator (moves 4-8)
No.	Move	Speaker	Utterance	
4	K1	B-4	I’m at Strathfield railway station	
5	K1	B-4	And I want I’m gonna go to Macquarie shopping centre	
6	cf	C	Right Strathfield station to Macquarie shopping centre	
7	rcf	B-4	Yep	
8	K2f	C	Ok	
K1 = provision of information; cf = confirmation; rcf = response to confirmation; K2f = feedback to information provided

Participants from each group responded differently to the provision of train travel information. Example 5 demonstrates how a Group A participant, A-2, requested information about catching a bus following the provision of train travel information by the call centre operator (move 40). 
In Example 5, participant A-2 carried on with the train travel information exchange (moves 27-39) instead of interrupting the call centre operator.  The belated request for bus information (move 40) resulted in a series of dynamic moves (moves 41-49) to clarify and facilitate the exchange. 
In contrast, two participants in Group B (Mild dysarthria) appeared unaware that they had been provided with inaccurate information (as specified by the task) and made no attempts to request bus information. Example 6 shows the response of participant B-3 following the provision of train travel information. 
Participant B-3 appeared unaware that the task was to obtain bus information and provided a follow-up K2 move (move 42) in response to the information provided. However, participant B-3 went on to request for specific information about the train (moves 43-46). 

Example 5:  A-2 = TBI participant; C = Call centre operator (moves 27-49)
No.	Move	Speaker	Utterance	
27	K1	C	Right from Strathfield station	
28	bch	A-2	yeah	
29	K1	C	You can actually take a train at 11 59	
30	bch	A-2	OK	
31	K1	C	getting you to Eastwood station	
32	bch	A-2	Ok	
33	K1	C	at 12 07	
34	bch	A-2	Ok	
35	K1	C	then you go to the corner of Um..	
36	sc	C	Well you go to the Leisure Lee Gardens Nursing Home at Eastwood	
37	bch	A-2	Yeah	
38	K1	C	and at 12.15 you catch a 611 bus	
39	K1	C	and that will take you to Macquarie shopping centre arriving at 12.22	
40	K2	A-2	and so how will I get there by bus?	
41	cfrq	C	How do you get there by bus?	
42	rcfrq	A-2	Yeah	
43	clrq	C	Ok did you want to just go by bus from Strathfield?	
44	rclrq	A-2	Yeah yeah	
45	cfrq	C	Bus only?	
46	rcfrq	A-2	yeah	
47	bch	C	ok	
48	jst	A-2	Sorry	
49	rjst	C	That’s ok no problem	
K1 = provision of information; bch = back-channel; sc = self-correct; cfrq = confirmation request; rcfrq = response to confirmation request; clrq = clarification request; rclrq = response to clarification request; jst = justification; rjst = response to justification

Example 6:  B-3 = TBI participant; C = Call centre operator (moves 41-46)
No.	Move	Speaker	Utterance	
41	K1	C	And it drops you off at Macquarie shopping centre at 12.20	
42	K2f	B-3	Oh Lovely	
43	K2	B-3	and um excuse me	
44	bch	C	Yep	
45	K2	B-3	I know it's at Strathfield railway station	
46	K2	B-3	but I was just wondering where we would catch the train?	
K1 = provision of information; K2f = follow up to information provided; K2 = information request; bch = back-channel

Another qualitative difference was the occurrence of communication breakdown due to mishearing of the information. This led to the provision of inaccurate information for one of the participants in Group A (Moderate dysarthria). However, this did not occur for any of the Group B (Mild dysarthria) participants.  Example 7 illustrates the exchange of inaccurate information due to mishearing. 

Example 7:  A-1 = TBI participant; C = Call centre operator (moves 8-17)
No.	Move	Speaker	Utterance	
8	K2	C	Ok can I get where you’re leaving from please?	
9	rprq	A-1	Pardon?	
10	rrprq	C	Could I get where you’re leaving from?	
11	rrprq	C	Where are you leaving ah from for your	
12	K1	A-1	um .. Strathfield station	
13	clrq	C	.. Station which station?	
14	rprq	A-1	Pardon?	
15	cfrq	C	Padstow station?	
16	rcfrq	A-1	. Yes	
17	K2f	C	Yes Ok	
K2 = information request; rprq = replay request; rrprq = response to replay request; K1 = provision of information; clrq = clarification requestion; cfrq = confirmation request; rcfrq = response to confirmation request; K2f = follow up to information provided; (.) = one second pause

In this example, the call centre operator misheard participant A-1’s replay request (move 14) as the name of a train station (move 15). This was followed by an inaccurate response, possibly also due to mishearing, by participant A-1 (move 16).  Therefore, participant A-1 was provided with information on how to get from Padstow station to Macquarie shopping centre, instead of from Strathfield station. This ultimately led to the wrong answer being provided to the enquiry. Participant A-1 did not correct this error, either due to an inability to detect she was being given the wrong information or an inability to repeat the service request. 

Listener comfort ratings
Table 7 shows the mean, range and standard deviation of the listener comfort scale ratings for each participant. Descriptive statistics were calculated for groups A (Moderate dysarthria) and B (Mild dysarthria).

Table 7.  Mean (M), range and standard deviation (SD) of listener comfort scale ratings
Participant No.	Mean	Range	SD	
Group A (Moderate dysarthria)	3.00	2	1.00	
A-1	2.00	2	0.74	
A-2	3.71	2	0.75	
A-3	3.04	4	1.25	
A-4	2.42	3	0.85	
A-5	4.00	4	1.11	

Group B (Mild dysarthria)	4.40	2	0.89	
B-1	4.04	4	1.23	
B-2	4.33	3	0.99	
B-3	3.79	4	1.18	
B-4	4.21	3	0.99	
B-5	6.29	2	0.66	

The Mann-Whitney U test was used to compare the listener comfort ratings for participants with moderate dysarthria (Group A) and participants with mild dysarthria (Group B). Group A participants (M = 3.00) had significantly lower ratings than Group B participants (M =4.40), U = 1.00, p < 0.05, r = -0.76. This meant that the listeners felt less comfortable about the speech of participants with moderate dysarthria after TBI (Group A). 

Relationship between listener comfort ratings and exchange structure
The application of Spearman’s rank order found no significant correlation between listener comfort ratings and all exchange structure moves. See Table 8.

Table 8.  Spearman’s rank order correlations between listener comfort and exchange structure moves
Exchange structure element	Listener comfort rating	
	rs	
Moves by TBI participants			
K1 moves/minute	 0.29	
K2 moves/minute	-0.04	
Dynamic moves/minute	 0.01	

Moves by call centre operators			
K1 moves/minute	 0.26	
K2 moves/minute	-0.31	
Dynamic moves/minute	 0.09	

Relationship between intelligibility and listener comfort ratings
Correlations between ASSIDS scores and listener comfort ratings were calculated using Spearman’s rank order. Significant correlations were found between listener comfort and total ASSIDS scores (rs = 0.71, p < 0.05), listener comfort and word intelligibility scores (rs = 0.71,  p < 0.05), and listener comfort and sentence intelligibility scores (rs = 0.87, p < 0.01).
Multiple regression analysis was conducted to determine how well listener comfort could be predicted by ASSIDS scores. Listener comfort could be predicted with 61% accuracy (Multiple R= 0.78, R2 = 0.61, adjusted R2 = 0.50, F = 5.51, df 1,7). 

Discussion

Relationship between intelligibility and exchange structure
	This study examined the everyday communication of individuals with mild and moderate dysarthria following TBI during service encounters with bus timetable call centre operators. It was hypothesised that individuals with moderate dysarthria would experience greater difficulty exchanging information during these encounters than individuals with mild dysarthria. However, this was not borne out by the results. Intelligibility did not affect the use of exchange structure moves by participants with moderate dysarthria when compared to those with mild dysarthria when interacting with call centre operators. 
This result is similar to that of previous findings where individuals with mild dysarthria following TBI were provided similar communication opportunities as matched controls during call centre interactions [28]. In addition, participants with TBI in the present study exhibited similar use of exchange structure moves as normal controls in the earlier study [49].  Thus, it appears that participants with both mild and moderate dysarthria following TBI in the present study were given similar communication opportunities when positioned as customers who required an information giving service. Intelligibility did not seem to affect the communication of participants with TBI when they were placed in the more powerful requesting role of customer with call centre operators. This more powerful role of customer is thought to be in part sustained by the amount of training and experience held by bus timetable call centre operators. That is, call centre operators provided a similar service to customers regardless of intelligibility differences.
 In New South Wales (NSW) Australia, all transport agencies and transport service providers have responsibilities to provide equitable access to transport service information under legislation and policies like the NSW Disability Services Act 1993  and the Commonwealth Disability Standards for Accessible Public Transport [50]. Efforts have been made to achieve such equitable access for people with a wide range of disabilities. This includes the education of transport staff including call centre operators, provision of telephone typewriter (TTY) facilities to assist people with hearing impairment, and having accessible information on websites [50]. Therefore, the bus timetable call centre operators were obligated and trained to provide a similar service to customers regardless of disability. It should be noted, however, that there are still many service providers in various sectors who do not provide accessible services for people with disabilities [51]. Such practices would make it difficult for people with disabilities, including individuals with TBI, to access goods, services and information. Training and education of service providers may be one way to improve access and the communicative effectiveness of individuals with TBI [52].  
It should be noted that even where intelligibility as measured by ASSIDS was moderately poor (i.e. 65-85% intelligible), the participants with TBI could generally be understood during the telephone interactions.  This could be due to the highly structured nature of a bus timetable service enquiry. For instance, all exchanges included a greeting, request for information, provision of information, closing remarks and closure sequence.  Therefore, the presence of a well described service encounter structure [27] may have resulted in similar use of exchange structure moves for participants with TBI and call centre operators in groups A (Moderate dysarthria) and B (Mild dysarthria).

Quality of telephone interactions
	While no quantitative differences were found in the nature of the exchange structure for groups A (Moderate dysarthria) and B (Mild dysarthria), qualitative differences were found. One of the participants in group A (Moderate dysarthria), participant A-1, was misheard by the call centre operator, and the lack of clarification resulted in an unsuccessful bus timetable service enquiry. Mishearing was not observed to occur for any participants in group B (Mild dysarthria). Therefore, the success of the bus timetable service enquiry may have been compromised by the reduced intelligibility of participant A-1. 
	The success of the bus timetable service enquiry may also have been affected by the cognitive-communication difficulties of participants from both groups. For instance, participants in both groups made incomplete information requests, a feature previously reported by Togher et al. [53], and responded inappropriately when provided with train travel information instead of bus travel information. Participants either requested clarification belatedly, or appeared unaware that inaccurate information had been provided. Participants with such problematic features tended to have lower recall and reasoning scores on the SCATBI than other participants. Therefore, these features may be explained by executive impairments which can lead to a failure in problem solving effectively and adapting to changing circumstances [54]. 
Individuals with TBI, particularly those with fronto-temporal and diffuse axonal involvement, can present with disruption of the capacity to focus attention voluntarily and to deal with novel situations adaptively.  Impaired drive can also result in inertia, rigidity, perseveration and inflexibility [55].  Participant A-1, for example, who had the most problematic call, failed to correct an error by the call centre operator, and showed evidence of inertia, through pausing and delayed responding during the telephone call. Participant A-1 presented with both a moderate spastic-ataxic dysarthria characterised by slow scanning speech, monotonous voice pitch and impaired articulatory precision, and a moderate cognitive-communication disability characterised by difficulty processing auditory information, problems formulating her request and a failure to detect and correct errors during the interaction.  The combination of motor speech impairments with cognitive-communication difficulties resulted in an unsuccessful request for information, even in a highly structured and straightforward service inquiry.  This indicates that both dysarthric impairments and cognitive linguistic functioning should be addressed in therapy to assist with relearning everyday communication tasks. 

Relationship between listener comfort ratings and exchange structure
Listener comfort ratings were not related to indices of exchange structure and therefore, may not have affected the way information was exchanged between participants with TBI and call centre operators. As discussed previously, this may be due to the more powerful interactional role that participants with TBI were in as a customer. Call centre operators have been described to be ‘controlled by customers’ [56] and are expected to be always friendly on the telephone [57]. In addition, call centre operators are expected not to express negative emotions even if they are present [56]. These rules and expectations need to be applied through routine interactions with numerous customers [58]. Adherence to these rules is often enforced by close performance monitoring [59].
The job requirements of call centre operators may have affected the results in two ways. Since call centre operators are expected not to display negative emotions, they may have felt uncomfortable about the speech of participants with TBI but did not react to it, resulting in similar use of exchange structure moves in both groups A (Moderate dysarthria) and B (Mild dysarthria).  In addition, listener comfort ratings were completed by speech pathology students and not the call centre operators. It may be possible that call centre operators held different listener comfort ratings to the speech pathology students due to the amount of experience they have in interacting with various customers.
Results may also be due to the highly structured nature of a bus timetable service enquiry. As mentioned previously, all exchanges included a greeting, request for information, provision of information, closing remarks and closure sequence typical of a service encounter structure [27]. In addition, call centre operators are often required to follow scripted dialogues during customer interactions [57]. Such highly structured customer interactions may have contributed to the lack of relationship between listener comfort ratings and how information was exchanged between participants with TBI and call centre operators. 

Relationship between intelligibility and listener comfort ratings
A significant relationship was found between intelligibility and listener comfort ratings and listener comfort ratings could be predicted with moderate accuracy by intelligibility. Participants with poorer intelligibility (Group A) were rated to be less comfortable to listen to than participants with better intelligibility (Group B). Therefore, intelligibility was found to play a role in determining listener comfort. This is similar to the results reported by Whitehill et al. [35], of intelligibility being a predictor of speech acceptability. 
Listener comfort was predicted with moderate accuracy, thus supporting our hypothesis that listener comfort ratings are influenced not only by speaker attributes but also listener attributes. For instance, one listener reported being ‘used to accents’ from travel experiences and thus may have required less ‘effort listening’ [40] to less intelligible speech.  This was supported by listener comfort ratings by that listener that were consistently higher than the mean ratings for all speakers. 
	That both speaker and listener attributes are important in determining listening comfort has several implications for dysarthria after TBI. Listener comfort may, like attitudes towards individuals with brain injury, be influenced by gender, socioeconomic status, religion [60] or even the cause of injury [61]. While the relationship between listener comfort, attitudes towards disability and brain injury and personal factors need to be further explored, listener comfort ratings may be a socially valid way of providing feedback to clients in therapy. The listener comfort scale may also be used as a functional tool to measure the outcomes of treatment, based on the use of speech in functional everyday contexts [11]. Alternatively, as listener comfort scores could be predicted with moderate accuracy from ASSIDS scores, there is also some preliminary support for the use of intelligibility scores as socially valid outcome measures. 
The listener comfort scale may also be useful in measuring the effectiveness of disability awareness training with service staff like call centre operators and public education of brain injury. Such training and education efforts are pertinent considering the possible stigmatization of individuals with brain injury and dysarthria [33,61]. In addition, the general public and non-expert health professionals have been found to possess inaccurate and inadequate knowledge about brain injury [62]. 

Conclusion
This study aimed to compare the everyday communication of individuals with mild and moderate dysarthria and concomitant cognitive-communication impairments following TBI using exchange structure analysis and listener comfort ratings during service encounters with bus timetable call centre operators. Results from exchange structure analysis indicate that participants with moderate dysarthria following TBI were not necessarily penalised for having poorer intelligibility during bus timetable service encounters. While the poorer intelligibility of participants with moderate dysarthria resulted in them having poorer listener comfort ratings, this did not affect the way information was exchanged with bus timetable call centre operators. These findings may be attributed to the more powerful interactional role of participants with TBI as customers, the amount of training and experience held by call centre operators and the highly structured nature of bus timetable service enquiries. 
These findings have important implications for the rehabilitation and community integration of individuals with TBI. Participation in everyday life activities includes planning travel and using public transport. Therefore, service encounters where individuals with TBI are placed in a more powerful interactional role of customer may be functional generalization tasks for individuals with TBI, even for those with moderate dysarthria. Practice on the telephone is a practical possibility in the clinic. In addition, the service encounters used may be varied according to the structure and complexity of the request. Training and education of service providers may also have a significant impact on the communicative effectiveness of individuals with TBI [52].

Limitations
This study had several limitations. Everyday communication was measured through discourse analysis of service encounters with bus timetable call centre operators. This offers only a snapshot of everyday communication. For most of us, everyday communication includes many other service encounters (e.g. bank transactions, shopping in a supermarket) and interactions (e.g. with friends and family).  More studies of individuals with and without dysarthria after TBI in other speaking situations with other communication partners would be valuable in adding to our understanding of their everyday communication skills. 
The listeners involved in the study were Year One speech pathology students. Although these students were new to the course and naïve listeners, it is uncertain if their ratings were affected by a budding professional identity as ‘future speech pathologists’. It is also uncertain if their ratings are representative of the wider population, including people of various socioeconomic backgrounds. The use of different listener groups in future would be helpful in determining possible differences in listener comfort. The relationship between listener comfort and attitudes towards dysarthria and brain injury also requires further investigation.
The findings were based on a small sample of participants and listeners and should be interpreted with caution.  Replication of these data with larger sample sizes would be helpful to further investigate the effect of dysarthria for individuals with TBI. 

Acknowledgements 
We wish to thank Christine Sheard, Alison Purcell, Cate Madill and Lynne Mortensen for their advice and assistance during the project. We would also like to thank the participants with TBI and the call centre operators from the NSW State Transit Authority for their assistance. The data collection was funded through a University of Sydney Sesqui Grant. 
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Appendix 1. Exchange structure: dynamic moves

Type of dynamic move	Code	
Tracking moves		
Forward channel	fch	
Back-channel	bch	
Replay request	rprq	
Response to replay request	rrprq	
Confirmation request	cfrq	
Response to confirmation request	rcfrq	
Clarification request	clrq	
Response to clarification request	rclrq	
Confirmation	cf	
Response to confirmation	rcf	
Check	check	
Response to check	rcheck	
Self-correct	sc	
Collocational prompt	cp	

Challenging moves		
Challenge	ch	
Response to challenge	rch	
Justification	jst	
Response to justification	rjst