Impaired processing speed in categorical perception: Speech perception of children who stutter

Abstract

There have been controversial debates across multiple disciplines regarding the underlying mechanism of developmental stuttering. Stuttering is often related to issues in the speech production system; however, the presence and extent of a speech perception deficit is less clear. This study aimed to investigate the speech perception of children who stutter (CWS) using the categorical perception paradigm to examine their ability to categorize different acoustic variations of speech sounds into the same or different phonemic categories. In this study, 15 CWS and 16 children who do not stutter (CWNS) completed identification and discrimination tasks involving acoustic variations of Cantonese speech sounds in three stimulus contexts: consonants (voice onset times, VOTs), lexical tones, and vowels. The results showed similar categorical perception performance in boundary position and width in the identification task and similar d' scores in the discrimination task between the CWS and CWNS groups. However, the reaction times (RTs) were slower in the CWS group compared with the CWNS group in both tasks. Moreover, the CWS group had slower RTs in identifying stimuli located across categorical boundaries compared with stimuli located away from categorical boundaries. Overall, the data implied that the phoneme representation evaluated in speech perception might be intact in CWS as revealed by similar patterns in categorical perception as those in CWNS. However, the CWS group had slower processing speeds during categorical perception, which may indicate an insufficiency in accessing the phonemic representations in a timely manner, especially when the acoustic stimuli were ambiguous.

The effect of overnight consolidation in the perceptual learning of non-native tonal contrasts

“…Compared to segments (e.g., Hindi dental and retroflex stops), which have been the focus of investigation in previous studies [19,22], lexical tones are highly variable and dynamic, requiring listeners to evaluate the pitch of the signal against the pitch range of the talker and continuously update this evaluation as the pitch contour unfolds over time [24–28] (see Fig 1 for the pitch contour of Cantonese and Mandarin tones). Further complicating the perceptual process, the same talker also shows variability in the production of tonal categories, thus also requiring listeners to evaluate the pitch they hear against the talker’s different realizations of the same tonal categories (within-category variations) and of different tonal categories (cross-category variations) [29–35]. Thus, it is both important and challenging for listeners to extract the abstract representations from tonal exemplars in order to generalize successfully across talkers [30].…”

The effect of overnight consolidation in the perceptual learning of non-native tonal contrasts

“…Different from segments (consonants and vowels), as illustrated in Fig 1, lexical tones are highly dynamic, requiring listeners to evaluate the pitch they hear in the signal against the pitch range of the talker and continuously update this evaluation as more of the pitch contour is heard over time [21][22][23][24][25]. Importantly, a given talker shows variability in the production of tonal categories, thus also requiring listeners to evaluate the pitch they hear against the talker's different realizations of the same tonal categories (within-category variations) and of different tonal categories (crosscategory variations) [26][27][28][29][30][31][32]. Thus, listeners need to extract the abstract representations from tonal exemplars in order to generalize successfully across talkers [27].…”

Voice onset time and formant onset frequencies in Arabic stuttered speech

“…Language acquisition studies report that lead/lag VOT dichotomy that Arabic follows is aerodynamically and articulatorily very difficult to acquire and maintain (Kakadelis, 2018). In different languages, lead stops are acquired after short lag stops and around the age of 5;0 (Gandour, Petty, Dardarananda, Dechongkit, & Mukongeon, 1986;Pan, 1994;Davis, 1995 an acoustic cue that discriminates voiceless from voiced plosives report slower processing speeds for PWS during categorical perception and difficulty in accessing phonemic representations in a timely manner (Bakhtiar, Zhang, & Ki, 2019).…”

“…VOT as a subtle fine-grained acoustic cue within a long lead/short lag language like Arabic markedly differentiates between PWS and FP and creates disruption to speech fluency. PWS slowdown of lead emphatics is due to a number of factors: the cognitive load lead VOT creates, the articulatory complexity word-initial emphatic consonants entail (Ward, 2017) and the slower processing speeds that PWS have during categorical perception of VOT (Bakhtiar et al, 2019) .Accordingly, PWS produce /d/ and /dˁ/ lead VOT with durations longer than those of FP. As the cognitive load increases with speakers moving from plain to emphatic plosives, PWS produce longer VOT for emphatic than plain plosives.…”