The effect of conductive hearing loss on the masking-level difference: insert versus standard earphones | JoVE Visualize

The effect of conductive hearing loss on the masking-level difference: insert versus standard earphones

J W Hall¹, J H Grose

¹Division of Otolaryngology/Head & Neck Surgery, University of North Carolina Medical School, Chapel Hill 27599-7070.

The Journal of the Acoustical Society of America|May 1, 1994

View abstract on PubMed

Summary

This study investigated if insert earphones improve masking-level differences (MLDs) for individuals with conductive hearing loss. Results showed insert earphones did not consistently improve MLDs, suggesting other factors beyond acoustic crosstalk are involved.

Area of Science:

Audiology
Auditory Neuroscience
Hearing Science

Background:

Masking-level difference (MLD) is reduced in conductive hearing loss.
The crosstalk hypothesis suggests reduced binaural cues due to bone conduction.
Insert earphones may mitigate this deficit due to high interaural attenuation.

Purpose of the Study:

To evaluate if insert earphones improve MLDs in normal-hearing and otosclerosis listeners.
To compare MLDs using TDH earphones versus insert earphones.
To explore the role of acoustic crosstalk and other factors in MLD deficits.

Main Methods:

Measured NoSo and NoS tau thresholds in normal-hearing and otosclerosis subjects.
Utilized TDH earphones with circumaural cushions and Etymotic 3A insert earphones.
Presented masking noise at fixed sound-pressure level and fixed sensation level.

Main Results:

Insert earphones did not consistently yield larger MLDs for either subject group or presentation level.
MLDs in hearing-impaired subjects remained abnormally small even with insert earphones and fixed sensation level.
Acoustic crosstalk played a role, but other factors like hearing asymmetry and phase mismatch were also implicated.

Conclusions:

Insert earphones do not fully restore normal masking-level differences in conductive hearing loss.
Factors beyond acoustic crosstalk, such as interaural asymmetry, contribute to MLD deficits.
Further research is needed to understand the complex mechanisms underlying MLD reduction in hearing impairment.