Assessment of a directional microphone array for hearing-impaired listeners

Area of Science:

• Audiology
• Acoustics
• Hearing Instrument Technology

Background:

• Hearing-impaired individuals struggle with speech comprehension in noisy or reverberant environments.
• Traditional hearing aid microphones have limitations in isolating speech signals.
• Array technology offers a potential solution for directional sound capture.

Purpose of the Study:

• To develop and clinically assess novel microphone array prototypes for hearing aids.
• To evaluate the effectiveness of broadside and endfire microphone arrays in improving speech reception in noise.
• To compare the performance of microphone arrays with conventional omnidirectional microphones.

Main Methods:

• Development of broadside and endfire microphone array prototypes with directional characteristics.
• Physical measurements of sound attenuation and signal-to-noise ratio improvement.
• Clinical assessment using a sound-insulated room, simulated speech, and diffuse background noise.
• Determination of speech-reception threshold in noise (SRT) for hearing-impaired subjects using monaural and binaural listening conditions.

Main Results:

• Broadside and endfire microphone arrays demonstrated significant improvements in speech reception thresholds in noise.
• Mean SRT improvement was 7.0 dB for the broadside array and 6.8 dB for the endfire array in monaural listening.
• Binaural listening with two endfire arrays provided binaural benefits comparable to natural hearing or conventional binaural hearing aids.

Conclusions:

• Directional microphone arrays, specifically broadside and endfire types, offer substantial benefits for hearing-impaired listeners in challenging acoustic environments.
• These array technologies can significantly enhance speech intelligibility by improving the signal-to-noise ratio.
• The findings support the clinical utility of microphone arrays in advanced hearing aid designs for improved auditory performance.