Loudness and the acoustic reflex: cochlear-impaired listeners

Area of Science:

• Audiology
• Hearing Science
• Speech Perception

Background:

• Understanding auditory perception in cochlear-impaired listeners is crucial for effective hearing aid fitting.
• The relationship between loudness perception (MCL, LDL) and acoustic reflex (AR) thresholds requires further investigation in impaired hearing.
• Speech intelligibility in noise is a significant challenge for individuals with cochlear impairments.

Purpose of the Study:

• To investigate the relationships among Most Comfortable Listening Level (MCL), Loudness Discomfort Level (LDL), and Acoustic Reflex (AR) thresholds to speech.
• To examine how noise and hearing aid status (unaided/aided) influence these auditory measures.
• To determine if the AR is a reliable predictor of MCL in cochlear-impaired listeners.

Main Methods:

• Cochlear-impaired listeners were tested using earphones and in a sound field.
• Speech materials were presented in quiet and with cafeteria noise (55 dB SPL).
• Measurements included MCL, LDL, and AR thresholds under unaided and aided conditions.

Main Results:

• MCL and AR thresholds were similar across conditions, while LDL was approximately 18 dB higher.
• The presence of noise elevated MCL but did not alter AR thresholds.
• AR thresholds were observed below the predicted level based on the loudness function.

Conclusions:

• While the acoustic reflex (AR) is strongly correlated with the most comfortable listening level (MCL) in cochlear-impaired listeners, a direct cause-effect relationship may not be present.
• Hearing aid use and noise conditions significantly impact loudness perception measures.
• The acoustic reflex may not fully represent the dynamic range of comfortable listening for impaired ears.