Amplified Earmuffs

Impact on Speech Intelligibility in Industrial Noise for Listeners With Hearing Loss

¹ Portland State University, Portland, OR

dolant{at}pdx.edu

Purpose: To determine how amplified earmuffs affect the intelligibility of speech in noise for people with hearing loss, and to determine how various brands of amplified earmuffs compare in terms of speech intelligibility and electroacoustic response.

Method: The Hearing in Noise Test (HINT) was used to measure the intelligibility of speech for 10 participants with hearing loss when they listened in a background of recorded industrial noise at 85 dBA. Participants listened with 3 different sets of amplified earmuffs (Peltor Tactical 7-S, Elvex COM 55, and Bilsom 707 Impact II), with a set of passive earmuffs (E-A-R Ultra 9000), and with ears unoccluded. Two measurements of sentence threshold were obtained under each of the 5 listening conditions. Gain was measured electroacoustically across a range of input levels and frequencies for each amplified earmuff.

Results: Electroacoustic measurements indicated that each electronic earmuff amplified at low input levels and attenuated at high input levels. However, gain characteristics varied greatly across devices. HINT sentence thresholds were not significantly different across the 5 listening conditions or across the 2 trials.

Conclusion: Results suggest that each type of earmuff can be used to reduce the noise exposure of people with hearing loss without compromising their ability to understand speech.

Key Words: amplified earmuffs, industrial noise, intelligibility, hearing loss, electroacoustics

Submitted on January 19, 2004
Accepted on January 14, 2005