Lombard Effect in Individuals With Nonphonotraumatic Vocal Hyperfunction: Impact on Acoustic, Aerodynamic, and Vocal Fold Vibratory Parameters

Abstract

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.

Supplemental material: https://doi.org/10.23641/asha.20415600.

Figure 1.

Experimental design and procedures. (a) Diagram illustrating the experimental setup for the acquisition of acoustic and aerodynamic measures of vocal function (left panel) and laryngeal imaging using high-speed videoendoscopy (HSV; right panel). (b) Diagram representing the different stages of the experimental session. Utterances and procedures are illustrated for each experimental condition. A timescale is not presented because the length of the vocalizations and the duration of the experimental session varied between participants.

Figure 2.

Acoustic and aerodynamic measures of the vocal function. (a) The behavior of the aerodynamic parameters as a function of the experimental condition: baseline (B), Lombard (L), and recovery (R). From left to right: vocal intensity (sound pressure level [SPL]), unsteady peak-to-peak airflow amplitude (ACFL), maximum flow declination rate (MFDR), flow-based laryngeal open quotient (OQ_f), and subglottal pressure (SGP). (b) Differences were denoted with Δ and computed between Lombard and baseline (L–B) and between recovery and baseline (R–B). Each box plot represents the mean (horizontal), the 25th and 75th percentiles (bounds of the box), and the 5th and 95th percentiles (whiskers). Outliers are presented for each group of participants (participants with typical voices and individuals with nonphonotraumatic vocal hyperfunction [NPVH]) in the different experimental conditions.

Figure 3.

Normalized aerodynamic measures of the vocal function as a function of the experimental condition: baseline (B), Lombard (L), and recovery (R). From left to right, we illustrate the normalized unsteady peak-to-peak airflow amplitude (ACFL'), the normalized maximum flow declination rate (MFDR'), the normalized flow-based laryngeal open quotient (OQ_f'), and the normalized subglottal pressure (SGP'). Each box plot represents the mean (horizontal), the 25th and 75th percentiles (bounds of the box), and the 5th and 95th percentiles (whiskers). Outliers are presented for each group of participants (participants with typical voices and individuals with nonphonotraumatic vocal hyperfunction [NPVH]) in the different experimental conditions.

Figure 4.

Vibratory measures of vocal function obtained from high-speed videoendoscopy as a function of the experimental condition: baseline (B), Lombard (L), and recovery (R). From top to bottom, the rows show the results for width-based open quotient (OQ_w), width-based speed quotient (SQ_w), left–right phase asymmetry (PA), and left–right amplitude asymmetry (AA), all for three anterior posterior positions (inferior, middle, and posterior). Each box plot represents the mean (horizontal), the 25th and 75th percentiles (bounds of the box), and the 5th and 95th percentiles (whiskers). Outliers are presented for each group of participants (participants with typical voices and individuals with nonphonotraumatic vocal hyperfunction [NPVH]) in the different experimental conditions.