Impact of Lombard effect in NPVH (Castro et al., 2022)

Purpose: This exploratory study aims to investigate variations in voice production in the presence of background noise (Lombard effect) in individuals with nonphonotraumatic vocal hyperfunction (NPVH) and individuals with typical voices using acoustic, aerodynamic, and vocal fold vibratory measures of phonatory function.

Method: Nineteen participants with NPVH and 19 participants with typical voices produced simple vocal tasks in three sequential background conditions: baseline (in quiet), Lombard (in noise), and recovery (5 min after removing the noise). The Lombard condition consisted of speech-shaped noise at 80 dB SPL through audiometric headphones. Acoustic measures from a microphone, glottal aerodynamic parameters estimated from the oral airflow measured with a circumferentially vented pneumotachograph mask, and vocal fold vibratory parameters from high-speed videoendoscopy were analyzed.

Results: During the Lombard condition, both groups exhibited a decrease in open quotient and increases in sound pressure level, peak-to-peak glottal airflow, maximum flow declination rate, and subglottal pressure. During the recovery condition, the acoustic and aerodynamic measures of individuals with typical voices returned to those of the baseline condition; however, recovery measures for individuals with NPVH did not return to baseline values.

Conclusions: As expected, individuals with NPVH and participants with typical voices exhibited a Lombard effect in the presence of elevated background noise levels. During the recovery condition, individuals with NPVH did not return to their baseline state, pointing to a persistence of the Lombard effect after noise removal. This behavior could be related to disruptions in laryngeal motor control and may play a role in the etiology of NPVH.

Table S1. Mean values and standard deviations for the acoustic and aerodynamic measures.

Table S2. Mean values and standard deviations for SPL-normalized measures.

Table S3. Mean values and standard deviations for vibratory measures.

Figure S1. Estimation of the parameters ACFL, MFDR, and OQ from airflow waveform. 

Figure S2. Estimation of the subglottic pressure from the intraoral pressure oral signal. 

Figure S3. Estimation of the anterior, middle, and posterior lines for computing the asymmetry parameters AP and AA from high-speed videoendoscopy (HSV).

Figure S4. Estimation of the parameters AP and AA from the digital kymograph obtained from HSV.

Castro, C., Prado, P., Espinoza, V. M., Testart, A., Marfull, D., Manriquez, R., Stepp, C. E., Mehta, D. D., Hillman, R. E., & Zañartu, M. (2022). Lombard effect in individuals with nonphonotraumatic vocal hyperfunction: Impact on acoustic, aerodynamic, and vocal fold vibratory parameters. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2022_JSLHR-21-00508