Lab Report 1 DESC 9115

Abstract

When a sound wave travels from the source it will disperse in different directions. The sound waves will continue until it is either out of energy or it hits a surface and reflects a different direction. When the receiver (an ear or microphone) hears the sound, it hears the direct sound coming straight from the sound source before hearing a delayed signal from a reflected surface. If the sound must travels further then there is more time for the direct signal to be heard, creating an echo, where as if it is close it will have more of a slap back or colouration effect. The parameters of the room are also important. If the sound is being reflected of many surfaces a flatter echo will occur. Some of the different effects that can be caused by delays are resonator, slap back and echo. One of the main differences between these effects is the delay time (τ), These effects are made by “comb filtering”. Comb filtering adds a delayed signal of the input to itself causing what is known as interference where the waves will either sum or subtract. There are two main types of signal processor comb filters, The feed forward (FIR) and the feedback (IIR).