Effectiveness of Asymmetrical Directional Micophone Configurations
Evaluating the effectiveness of asymmetrical directional microphone configurations on BTE hearing aids
Hearing aid bilateral fitting in hearing impaired subjects raises some problems concerning the interaction of the perceptual binaural properties with the directional characteristics of the device. Particularly, the benefit of directional cardiod microphones (DD), aiming to facilitate frontal speech perception in noisy environments, is controversial, as many users still opt for the use of an omnidirectional microphone configuration (OO). Attempts to use an asymmetrical (OD/DO) microphone configuration (omnidirectional in one side, and directional in the opposite) did not demonstrate decisive advantages compared to a symmetrical directional mode, although this seem not to worsen the performances in terms of speech recognition.
This experiment aims to establish whether and to which extent in a sample of 10 normally hearing subjects the binaural changes in the speech-to-noise level ratio (s/n), caused by different microphone configurations (OO, DD, OD and DO) and different positions of the speech signal (frontal or lateral), could alter the performances of the speech recognition in noise: Speech Reception Thresholds (SRT) in noise have been measured monolaterally and bilaterally in order to properly investigate the role of the binaural interaction in the perception of reproduced signals.
This study has been funded by the RIF2010 (Revolving Investment Fund, DMU) within the Multimedia and Audiology Network (MAN) project (see http://www.cse.dmu.ac.uk/~lpicinali/MAN/MAN.html)
Participants: Lorenzo Picinali, Silvano Prosser (Unviersità di Ferrara, Italy).