The effects of noise on thresholds obtained with a supra-aural earphone and a muffed insert earphone
Swim, Kristine M.
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Hearing thresholds were assessed using a standard supra-aural earphone (SSE) and a muffed insert earphone (MIE) in an environment of specially shaped noise. Eleven women with normal hearing sensitivity were the subjects of this project and were evaluated under four test conditions: supra-aural earphone in quiet, supraaural earphone in noise, muffed insert earphone in quiet, muffed insert earphone in noise. Results of an analysis of variance revealed significantly higher thresholds with the SSE compared to the MIE in the noise test condition. Essentially no threshold shift occurred with the muffed insert earphone in any condition. It was concluded that the MIE is more appropriate than the SSE for testing hearing sensitivity in the presence of moderate amounts of ambient noise. Hearing levels can be accurately assessed using the MIE system in levels of noise that are equal to OSHA maximum permissible levels. Subjective comfort ratings of each earphone revealed no difference between the two systems.