The influence of amplitude modulation frequency on perceived roughness of vowels.
Rahul Shrivastav, David A. Eddins · The Journal of the Acoustical Society of America · 2011
The goal of the current experiment is to determine how perceived roughness of vowels is influenced by the frequency of inherent amplitude modulation. A set of 10 vowel stimuli was synthesized using a Klatt synthesizer and were modeled after ten talkers selected from the Satloff/Heman-Ackah disordered voice database. These vowels were selected using stratified sampling procedures to represent a wide range of roughness. The vowel f0 and the first three formants were determined and used to generate a synthetic copy of these vowels. The aspiration noise level was adjusted to subjectively match the overall quality of the talkers. To each of the ten prototypical vowels, sinusoidal amplitude modulation was superimposed with a modulation depth of −6 dB and modulation frequencies ranging from 10 to 70 Hz. Listeners judged roughness in a matching task where the modulation depth of a comparison sound was adjusted to match the perceived roughness of each of the 70 speech stimuli (10 talkers × 7 modulation frequencies). The dependence of perceived roughness on amplitude modulation frequency will be compared to the perceived roughness of sinusoidal carriers as reported by Fastl and Zwicker (Springer, New York, 1997).