Related Experiment Videos
Real ear attenuation at threshold for three audiometric headphone devices: implications for maximum permissible
J R Franks1, D P Engel, C L Themann
1Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety and Health, Cincinnati, Ohio.
Ear and Hearing
|February 1, 1992
Summary
Standard headphone cushions and enclosures do not adequately reduce ambient noise for accurate hearing tests. Even noise-excluding devices fail to meet Occupational Safety and Health Administration standards for low-level threshold assessment.
Area of Science:
- Audiology
- Occupational Health
- Acoustics
Background:
- Accurate hearing threshold assessment requires minimizing ambient noise interference.
- Existing standards for maximum permissible ambient noise levels may not be sufficiently stringent.
- Headphone attenuation performance is critical for reliable audiometric testing in noisy environments.
Purpose of the Study:
- To measure the sound attenuation of specific headphone devices using the ANSI S12.6-1984 protocol.
- To evaluate the adequacy of current noise standards (ANSI S3.1-1977, OSHA 1983) for pure-tone threshold assessment.
- To analyze discrepancies in attenuation values compared to previous reports.
Main Methods:
- Attenuation measurements were conducted on Telephonics headsets with TDH-50P earphones and Model 51 cushions.
- Amplivox Audiocups and Peltor AudioMate headphone enclosures, each housing the same earphones, were tested.
- Pure-tone threshold shifts were estimated based on measured attenuation under specified noise conditions.
Main Results:
- Model 51 cushions alone provided insufficient attenuation for ambient noise levels permitted by ANSI S3.1-1977.
- Noise-excluding headphone enclosures did not sufficiently reduce background noise to meet OSHA (1983) standards.
- Testing down to 0 dB HL was not feasible with the tested configurations under current noise standards.
Conclusions:
- Current noise standards may be inadequate for accurate pure-tone threshold audiometry, especially at lower hearing levels.
- Improvements in headphone design or stricter noise regulations are needed for reliable hearing assessments.
- The tested headphone configurations do not guarantee accurate threshold measurements in environments compliant with existing noise standards.