Auditory Spectral Integration in the Perception of Static Vowels

Abstract

Purpose To evaluate potential contributions of broadband spectral integration in the perception of static vowels. Specifically, can the auditory system infer formant frequency information from changes in the intensity weighting across harmonics when the formant itself is missing? Does this type of integration produce the same results in the lower (F1) and higher (F2) regions? Does the spacing between the spectral components affect a listener’s ability to integrate the acoustic cues? Method Twenty young listeners with normal hearing identified synthesized vowel-like stimuli created for adjustments in the F1 (/ʌ/- /ɑ/, /ɪ/-/ɛ/) and in the F2 region (/ʌ/-/æ/). There were two types of stimuli: (1) two-formant tokens and (2) tokens in which one formant was removed and two pairs of sine waves were inserted below and above the missing formant; the intensities of these harmonics were modified to cause variations in their spectral center-of-gravity (COG). The COG effects were tested over a wide range of frequencies. Results Obtained patterns were consistent with calculated changes to the spectral COG, both in F1 and F2 regions. The spacing of the sine waves did not affect listeners’ responses. Conclusion The auditory system may perform broadband integration as a type of auditory wideband spectral analysis.

Timbre and Speech Perception in Bimodal and Bilateral Cochlear-Implant Listeners

“…This model considers that vowels can be correctly identified based on global spectral characteristics rather than individual formants; thus, correct vowel recognition relies on the integration of broadband spectral information. A recent study by Fox et al (2011) demonstrated the important role of spectral centroid in both F1 and F2 regions for vowel perception. Fox et al replaced one of the formants in a two-formant stimulus with two pairs of sine waves.…”

Dynamic Spectral Structure Specifies Vowels for Adults and Children

“…In fact, the earliest instrumental analyses of speech readily yielded descriptions of vowels based on formant frequencies at stable regions within syllables (e.g., Joos, 1948; Potter & Steinberg, 1950). As a consequence, perceptual accounts have tended to attribute vowel recognition to the frequencies of the first two or three formants at steady-state regions (e.g., Clark, 2003; Ferrand, 2007; Ladefoged, 1982; Tye-Murray, 2009), and research into the nature of vowel recognition for static spectral signals continues (e.g., Fox, Jacewicz, & Chang, 2011). Of course, these accounts must be accurate for vowels spoken in isolation, but it is the rare utterance occurring in natural environments that consists of an isolated vowel.…”

Categorization of Natural Whistled Vowels by Naïve Listeners of Different Language Background

“…It has been shown to play an important role in vowel identification because greater formant convergence explains better performance in vowel identification and a better stability of vowels in short-term memory (e.g., Schwartz and Escudier, 1989). Moreover, this phenomenon also explains why vowels of different spectra can be matched with the same vowel (Fox et al, 2011). The results of the French speakers could be analyzed under this frame.…”