Impact of Hearing Protection and Background Noise on the Voice of Steam Train Engineers
Channel: Desi Gutierrez
Date: 2020-05-15

Desi Gutierrez, BA, MA Graduate Student, Dept. of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, desi-gutierrez@uiowa.edu

Pasquale Bottalico, PhD, Assistant Professor, Dept. of Speech and Hearing Science, University of Illinois at Urbana-Champaign, Champaign, IL, pb81@illinois.edu

Supraja Anand, PhD, Assistant Professor, Dept. of Communication Sciences and Disorders, University of South Florida, Tampa, FL, suprajaanand@usf.edu

Objective: Exposure to background noise triggers an alteration in the speech production mechanism referred to as the Lombard effect. Although well-studied, prior research is largely focused on teachers. This study investigated Lombard effect in steam train engineers, who constantly communicate for safety and proper operation of the trains. Due to hazardous levels of exposure to background noise, steam train engineers are required to wear hearing protection devices (HPDs). Such devices alter the wearer’s perception of his/her own voice and also lead to changes in speech production. To our knowledge, no studies have examined these effects and their combination among steam train engineers, for whom the implications are likely to be significant.

Methods/Design: Thirteen steam train engineers phonated vowel /a/, read a phrase, and described a map under different noise and HPD conditions. Background noises with similar loudness equivalent levels but different spectral shapes were selected from multiple steam train recordings. Objective acoustic measures of relative sound pressure level (∆SPL) and relative fundamental frequency (∆fo) were extracted from all stimuli. Participants also subjectively reported their vocal effort and vocal disturbance using a 100 mm visual analog scale.

Results and conclusions: In the presence of background noise, participants significantly raised their ∆SPL and ∆fo compared to silent conditions demonstrating a Lombard effect. In the presence of background noise and HPDs, they significantly decreased their ∆SPL and ∆fo. On the contrary, there was an increase in ∆SPL in the silence condition when the participants wore HPDs. Additionally, participants perceived decreased vocal disturbance as a result of HPDs. Majority of the research examining the effects of hearing protection on speech communication has focused on the listener. Understanding the changes in voice and speech production by talkers who are required to wear HPDs can provide the basis for developing better communication in noisy environments.