The effect of sound field amplification systems on vocal demand response in teachers during lessons

Abstract

Purpose

Sound pressure level (SPL), fundamental frequency (F₀), time dose (D_t), cycle dose (D_c), and distance dose (D_d) are components affecting a vocal demand response. The study aimed to investigate the impact of sound field amplification systems (SFAS) on teachers’ vocal parameters and determine the user comfort of SFAS use in teachers.

Methods

Twenty female teachers underwent long-term voice dosimetry with Vocal Holter Med (PR.O.Voice Srl) during everyday teaching activities. The SFAS PentaClassRuna (Certes) was installed in classrooms. Voice dosimetry was provided in two different acoustical conditions—without the use of SFAS (one to two days) and with SFAS (one to three days). Teachers underwent voice acoustic and laryngoscopic evaluation before voice dosimetry. Two teachers’ groups were formed: teachers with and without vocal nodules. The visual analogue scale measured the user comfort of SFAS.

Results

There were no significant differences in vocal parameters and vocal doses between teachers with and without vocal nodules. Voice amplification significantly decreased average F₀(−4.4 Hz), D_t%(−3.1%), D_c (−0.4 kcycles), and D_d (−1.3 m) in teachers without vocal nodules and F₀ (−8.9 Hz) in teachers with vocal nodules. Vocal doses (D_t%, D_c, D_d) significantly decreased in classrooms with longer reverberation time. The user comfort of the SFAS during the lessons was high in both teachers groups.

Conclusions

SFAS was a mediator between the classroom’s environment and the teacher’s vocal demand response; it changed teachers’ voice production parameters and reduced vocal demand response to satisfy the communication requirements. In addition, voice amplification was more beneficial for teachers without vocal fold lesions.

Keywords:

• Teachers
• vocal nodules
• vocal demand response
• voice amplification
• vocal dose
• sound pressure level
• fundamental frequency
• reverberation time
• voice dosimetry

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by European Regional Development Fund. Post-doctoral Research Aid, N 1.1.1.2/16/I/001 supported this research; research project “The long-term effects of sound amplification systems on teachers’ vocal load and comprehension of verbal instructions of children,” 1.1.1.2/VIAA/1/16/001.