Effects of spectral slope on perceived breathiness in vowels

Abstract

Previous studies have indicated that breathiness is correlated with changes in spectral slope as well as aspiration noise [Klatt & Klatt, ‘‘Analysis, synthesis, and perception of voice quality variations among female and male talkers,’’ J. Acoust. Soc. Am. 87, 820–857 (1990)]. In a recent study, Shrivastav and Pinero [Shrivastav & Pinero ‘‘Effect of aspiration noise and spectral slope on perceived breathiness in vowels,’’ J. Acoust. Soc. Am. 117, 2622 (2005)] observed that varying spectral slope resulted in minimal changes on the perceived breathiness for synthetic vowels. However, the stimuli tested in this experiment included a relatively narrow range of spectral slope variation. The goal of the present experiment was to verify the role of spectral slope on the perception of breathiness by testing stimuli that had a wider range of variation in spectral slope. Ten voices (5 male and 5 female) were synthesized using a Klatt synthesizer. Each of these was manipulated to generate two continua varying in their spectral slope from −3 to −30 dB/octave. One continuum had a constant cutoff frequency of 500 Hz, while the other continuum had a cutoff frequency between the second harmonic (H2) and the third harmonic (H3). Ten listeners judged the degree of breathiness using a 7-point rating scale. Preliminary results suggest that spectral slope has minimal effect on the perception of breathiness in synthetic vowels. [Research supported by NIH/R21 DC006690.]