The Perception of Breathiness in the Voices of Pediatric Speakers

Abstract

Background: The perception of pediatric voice quality has been investigated using clinical protocols developed for adult voices and acoustic analyses designed to identify important physical parameters associated with normal and dysphonic pediatric voices. Laboratory investigations of adult dysphonia have included sophisticated methods, including a psychoacoustic approach that involves a single-variable matching task (SVMT), characterized by high inter- and intra-listener reliability, and analyses that include bio-inspired models of auditory perception that have provided valuable information regarding adult voice quality.

Objectives: To establish the utility of a psychoacoustic approach to the investigation of voice quality perception in the context of pediatric voices?

Methods: Six listeners judged the breathiness of 20 synthetic vowel stimuli using an SVMT. To support comparisons with previous data, stimuli were modeled after four pediatric speakers and synthesized using Klatt with five parameter settings that influence the perception of breathiness. The population average breathiness judgments were modeled with acoustic measures of loudness ratio, pitch strength, and cepstral peak.

Results: Listeners reliably judged the perceived breathiness of pediatric voices, as with previous investigations of breathiness in adult dysphonic voices. Breathiness judgments were accurately modeled by loudness ratio (r² = 0.93), pitch strength (r² = 0.91), and cepstral peak (r² = 0.82). Model accuracy was not affected significantly by including stimulus fundamental frequency and was slightly higher for pediatric than for adult voices.

Conclusions: The SVMT proved robust for pediatric voices spanning a wide range of breathiness. The data indicate that this is a promising approach for future investigation of pediatric voice quality.

Keywords: Breathiness; Listener perception; Matching task; Pediatric dysphonia.

Figure 1

Fourier spectra of AH-OQ for two synthetic talkers. Both talkers are based on the same natural voice and represent the two endpoints of the breathy continuum (continuum positions 1 and 5) where position 1 represents a voice with a low degree of breathiness and position 5 represents a voice with high degree of breathiness. Values in the inset of each panel highlight the acoustic indices described the text.

Figure 2

Matching NSR by continuum position. The mean ± SE are given, averaged over all listeners.

Figure 3

Matching NSR by loudness ratio in dB. The mean ± SE are given, averaged over all listeners. Black symbols are for pediatric voices, with symbol type separating the four different talkers. Grey symbols correspond to adult voices from Shrivastav et al. (2011). Lines with the same shading scheme represent linear regression. In both cases, goodness of fit was high (pediatric voices: r² = 0.93; adult voices: r² = 0.72).

Figure 4

Matching NSR by pitch strength. The mean ± SE are given, averaged over all listeners. Black symbols are for pediatric voices, with symbol type separating the four different talkers. Grey symbols correspond to adult voices from Shrivastav et al. (2011). Lines with the same shading scheme represent linear regression. In both cases, goodness of fit was high (pediatric voices: r² = 0.91; adult voices: r² = 0.71).

Figure 5

Matching NSR by cepstral peak in dB. The mean ± SE are given, averaged over all listeners. Black symbols are for pediatric voices, with symbol type separating the four different talkers. Grey symbols correspond to adult voices from Shrivastav et al. (2011). Lines with the same shading scheme represent linear regression. In both cases, goodness of fit was high (pediatric voices: r² = 0.82; adult voices: r² = 0.91).