A psychoacoustic method for studying the necessary and sufficient perceptual cues of American English fricative consonants in noise

Abstract

In a previous study on plosives, the 3-Dimensional Deep Search (3DDS) method for the exploration of the necessary and sufficient cues for speech perception was introduced (Li et al., (2010). J. Acoust. Soc. Am. 127(4), 2599-2610). Here, this method is used to isolate the spectral cue regions for perception of the American English fricatives /∫, 3, s, z, f, v, θ, δ in time, frequency, and intensity. The fricatives are analyzed in the context of consonant-vowel utterances, using the vowel /α/. The necessary cues were found to be contained in the frication noise for /∫, 3, s, z, f, v/. 3DDS analysis isolated the cue regions of /s, z/ between 3.6 and 8 [kHz] and /∫, 3/ between 1.4 and 4.2 [kHz]. Some utterances were found to contain acoustic components that were unnecessary for correct perception, but caused listeners to hear non-target consonants when the primary cue region was removed; such acoustic components are labeled "conflicting cue regions." The amplitude modulation of the high-frequency frication region by the fundamental F0 was found to be a sufficient cue for voicing. Overall, the 3DDS method allows one to analyze the effects of natural speech components without initial assumptions about where perceptual cues lie in time-frequency space or which elements of production they correspond to.

Within-consonant perceptual differences in the hearing impaired ear

“…The lower the SNR 90 , the more robust a token is to noise. For NH listeners, this psychoacoustic measure has been found to be significantly correlated to the physical intensity of the necessary consonant cue region, with tokens that have more intense cue regions having lower SNR 90 values (R egnier and Allen, 2008;Li et al, 2010;Li et al, 2012). As discussed in Sec.…”

“…The NH SNR 90 has been found to significantly correlate with the intensity of the time-frequency region that contains the primary consonant cues (R egnier and Allen, 2008;Li et al, 2010;Li et al, 2012;Kapoor and Allen, 2012). Thus the NH DSNR 90 relates the difference in intensity of the NH consonant cue regions.…”

“…NH listener psychoacoustic data for the 28 test tokens (14 consonants) used in the present study were collected by Phatak and Allen (2007) and Li (2011). High-/low-pass filtering and time-truncation data allow one to identify, in each naturally variable token, the spectral timefrequency region that contains the acoustic components that are necessary for correct perception, we refer to this as the necessary cue region (Li et al, 2010;Li et al, 2012). The acoustic components that encode the primary cues fall within this necessary cue region.…”

“…Previous studies have shown that for individual consonant tokens, the intensity of each necessary cue region is correlated to the robustness to noise for NH listeners (R egnier and Allen, 2008;Li et al, 2010;Li et al, 2012;Kapoor and Allen, 2012). We test if natural variations in the intensity of the acoustic cue region that affect NH perception at low SNRs would similarly affect HI perception at higher SNRs.…”

“…Multiple tokens of the same consonant, by different talkers or with different vowels, are often considered as multiple measures of the same effect. In contrast to this approach, the consonant cue literature has documented, in detail, the variability of the cues that are present in naturally produced speech (Baum and Blumstein, 1987;Dorman et al, 1977;Herd et al, 2010;Jongman et al, 2000;Kurowski and Blumstein, 1987;Li et al, 2010;Li et al, 2012). This variability is quantified by an analysis of the acoustical properties of each individual consonant token and can be observed across speech samples that are unambiguous (no confusions) and robust to noise (error <10%).…”