Effect of reverberation and amplification on sound localisation Essay

Effect of reverberation and amplification on sound localisation - Essay Example Binaural cues are based on the processing of differences in intensity, time and frequency correlation between both ears in the central nervous system. Localisation can be affected by any number of factors, including age, hearing loss, gender, handedness, environmental conditions and sound variations. An important factor in sound localisation is reverberation, which affects auditory perception and can provide listeners with a cue for sound distance. Reverberation refers to the acoustic environment that surrounds a sound, and is defined as the combined effect of multiple sound reflections within a room. Hearing loss may affect listening in reverberation by distorting the speech spectrum, therefore it is interesting to further investigate the effect of reverberation on speech localisation. Sound localisation may also be affected by hearing aids, as these may affect the localisation cues. Sound localisation therefore can be both negatively and positively affected by hearing aids. Directi onal microphones may disrupt binaural cues for localisation, as they can artificially change the inter-aural level and phase differences, which are both critical cues for localisation. ... However, previous studies are contradictory as to whether bilateral or unilateral hearing aids are better when in terms of sound localisation. The main purpose of the present study is to investigate the contribution of adding reverberation on a listening environment to the abilities of normal hearing and hearing impaired listeners in localising speech and non-speech signals, and to evaluate whether it is necessary to add reverberant environments in clinical testing. Another objective of the study will be to determine if adding reverberation makes localisation more challenging for hearing impaired listeners in comparison to normal hearing listeners. The second main purpose of the present study is to understand the effect of the hearing loss and the hearing aid amplification systems on the utilization of the localisation cues in reverberant and anechoic environments. These two factors will be investigated separately by comparing the hearing impaired performances with and without hearin g aids in both listening environments. 1.2 Thesis Outline Chapter 1 Introduction Chapter 2 Background and Literature Review. This chapter introduces the concepts and literature on horizontal sound localisation in both normal and hearing impaired listeners. Background information on reverberation, and what is known on the effects of reverberation on our ability to localise sound sources in the horizontal plane, is also introduced. Chapter 3 Experimental Design. This chapter describes the experimental set-up and apparatus used in the localisation experiments in the thesis. It will further provide some details of the stimuli, reverberation, and the methods, used in simulating different reverberant environments. Chapter 4 KEMAR Measurements. This chapter reports the measurements