Weighting Of Acoustic Cues Research Articles

The perception and production of Korean stops in second dialect acquisition.

This study investigated the acoustic cue weighting of the Korean stop contrast in the perception and production of speakers who moved from a nonstandard dialect region to the standard dialect region, Seoul. Through comparing these mobile speakers with data from nonmobile speakers in Seoul and their home region, it was found that the speakers shifted their cue weighting in perception and production to some degree, but also retained some subphonemic features of their home dialect in production. The implications of these results for the role of dialect prestige and awareness in second dialect acquisition are discussed.

Perceptual weighting of acoustic cues to contrastive prosody for sentences in quiet and in noise

Prosody is used to mark important information in speech, yet despite this important role in everyday communication it is not a customary part of speech recognition testing in routine audiometry. Listeners might fail to perceive meaningful emphasis on a specific word signaled by prosodic cues despite repeating the words correctly. This study introduces a new paradigm for assessing perception of prosodic cues that are used to signify new/corrective information in a sentence. Stimuli consisted of spoken sentences where one word (in various sentence positions) was emphasized through acoustic modifications across the entire utterance, in a manner that corrected wrong information. Participants used a visual analog scale to mark the timing and degree of emphasis aligned with the target words. Perceptual data in this study are linked with acoustic measures of voice pitch contour, intensity, and duration to characterize how contrastive stress cues are recovered by listeners with and without cochlear implants, who are especially at risk for poorer pitch perception. Follow-up conditions used stimuli where acoustic cues (F0, duration, intensity) were manipulated independently to explore perceptual cue weighting, and the perseverance of these cues through background noise.

Limits of short-term perceptual training for enhancing Seoul-Korean listeners’ use of English lexical stress in spoken word recognition

This study investigates whether short-term perceptual training can enhance Seoul-Korean listeners’ use of English lexical stress in spoken word recognition. Unlike English, Seoul Korean does not have lexical stress (or lexical pitch accents/tones). Seoul-Korean speakers at a high-intermediate English proficiency completed a visual-world eye-tracking experiment adapted from Connell et al. (2018) (pre-/post-test). The experiment tested whether pitch in the target stimulus (accented versus unaccented first syllable) and vowel quality in the lexical competitor (reduced versus full first vowel) modulated fixations to the target word (e.g., PARrot; ARson) over the competitor word (e.g., paRADE or PARish; arCHIVE or ARcade). In the training (eight 30-min sessions over eight days), participants heard English lexical-stress minimal pairs uttered by four talkers (high variability) or one talker (low variability), categorized them as noun (first-syllable stress) or verb (second-syllable stress), and received accuracy feedback. The results showed that neither training increased target-over-competitor fixation proportions. Crucially, the same training had been found to improve Seoul- Korean listeners’ recall of English words differing in lexical stress (Tremblay et al., 2022) and their weighting of acoustic cues to English lexical stress (Tremblay et al., 2023). These results suggest that short-term perceptual training has a limited effect on target-over-competitor word activation.

The acoustic cue-weighting and the L2 production-perception link: A case of English-speaking adults’ learning of Korean stops

The current study examined English-speaking adult learners’ production and perception of L2 Korean stops (/t/ or /t’/ or /t^h/) to investigate whether the two modalities are linked in utilizing voice onset time (VOT) and fundamental frequency (F0) for the L2 sound distinction and how the learners’ L2 proficiency mediates the relationship. Twenty-two English-speaking learners of Korean living in Seoul participated in the word-reading task of producing stop-initial words and the identification task of labelling CV stimuli synthesized to vary VOT and F0. Using logistic mixed-effects regression models, we quantified group- and individual-level weights of the VOT and F0 cues in differentiating the tense-lax, lax-aspirated, and tense-aspirated stops in Korean. The results showed that the learners as a group relied on VOT more than F0 both in production and perception (except the tense-lax pair), reflecting the dominant role of VOT in their L1 stop distinction. Individual-level analyses further revealed that the learners’ L2 proficiency was related to their use of F0 in L2 production and their use of VOT in L2 perception. With this effect of L2 proficiency controlled in the partial correlation tests, we found a significant correlation between production and perception in using VOT and F0 for the lax-aspirated stop contrast. However, the same correlation was absent for the other stop pairs. We discuss a contrast-specific role of acoustic cues to address the non-uniform patterns of the production-perception link in the L2 sound learning context.

Strategic perceptual weighting of acoustic cues for word stress in listeners with cochlear implants, acoustic hearing, or simulated bimodal hearing.

Perception of word stress is an important aspect of recognizing speech, guiding the listener toward candidate words based on the perceived stress pattern. Cochlear implant (CI) signal processing is likely to disrupt some of the available cues for word stress, particularly vowel quality and pitch contour changes. In this study, we used a cue weighting paradigm to investigate differences in stress cue weighting patterns between participants listening with CIs and those with normal hearing (NH). We found that participants with CIs gave less weight to frequency-based pitch and vowel quality cues than NH listeners but compensated by upweighting vowel duration and intensity cues. Nonetheless, CI listeners' stress judgments were also significantly influenced by vowel quality and pitch, and they modulated their usage of these cues depending on the specific word pair in a manner similar to NH participants. In a series of separate online experiments with NH listeners, we simulated aspects of bimodal hearing by combining low-pass filtered speech with a vocoded signal. In these conditions, participants upweighted pitch and vowel quality cues relative to a fully vocoded control condition, suggesting that bimodal listening holds promise for restoring the stress cue weighting patterns exhibited by listeners with NH.

Individual Differences in Categorical Judgment of L2 Stops: A Link to Proficiency and Acoustic Cue-Weighting.

This study investigated individual differences in Korean adult learners' categorical perception of L2 English stops with an aim to explore the relationship of gradient categorizations to perceptual sensitivity to acoustic cues and L2 proficiency. Korean young adult L2 learners of English (N = 49) participated in two speech perception tasks (visual analog scaling and forced-choice identification) in which they listened to English voiced and voiceless stops and Korean lax and aspirated stops with Voice Onset Time (VOT) and F0 manipulated to form a continuum. It was found that in both L1 and L2 stop perception, listeners' gradient category judgment was associated with greater reliance on language-specific redundant cues (i.e., F0 in L2 English and VOT in L1 Korean) and that in the perception of L2 stops, categorical listeners who tended to be less sensitive to F0 were the ones with a higher level of L2 English proficiency. The results suggest that the categorical manner of judging L2 stops reflects learners' better knowledge of L2-specific acoustic cue-weightings, based on which less relevant acoustic information is effectively suppressed.

Learning to Perceive Non-Native Tones via Distributional Training: Effects of Task and Acoustic Cue Weighting.

As many distributional learning (DL) studies have shown, adult listeners can achieve discrimination of a difficult non-native contrast after a short repetitive exposure to tokens falling at the extremes of that contrast. Such studies have shown using behavioural methods that a short distributional training can induce perceptual learning of vowel and consonant contrasts. However, much less is known about the neurological correlates of DL, and few studies have examined non-native lexical tone contrasts. Here, Australian-English speakers underwent DL training on a Mandarin tone contrast using behavioural (discrimination, identification) and neural (oddball-EEG) tasks, with listeners hearing either a bimodal or a unimodal distribution. Behavioural results show that listeners learned to discriminate tones after both unimodal and bimodal training; while EEG responses revealed more learning for listeners exposed to the bimodal distribution. Thus, perceptual learning through exposure to brief sound distributions (a) extends to non-native tonal contrasts, and (b) is sensitive to task, phonetic distance, and acoustic cue-weighting. Our findings have implications for models of how auditory and phonetic constraints influence speech learning.

Perceptual weighting of acoustic cues for word stress in normal hearing listeners and cochlear implant users

Accurate perception of word stress is key to segmenting and understanding speech. We examined perception of four acoustic cues to word stress in English—vowel quality (VQ), pitch, syllable duration, and intensity—and how perception of these cues is affected by specific kinds of signal degradation. Cochlear implants (CIs) severely degrade VQ and pitch, which could demand different relative reliance on these cues. We tested NH listeners in unprocessed, vocoded, and simulated bimodal (unprocessed low frequencies, vocoded high frequencies) conditions as well as CI users. Stimuli included stress-contrastive word pairs (DESert versus dessERT, SUBject versus subJECT) with orthogonal manipulations of each cue. For both NH and CI listeners, there were strikingly different patterns of cue weighting between these word pairs, highlighting how stress cue weighting is flexible across words rather than being absolute. Vocoding the stimuli led to a downweighting of VQ and pitch cues and a compensatory upweighting of duration and intensity; perception of pitch and VQ were largely restored in the bimodal conditions with 250 and 800 Hz bands preserved, respectively. CI users relied on duration more than the NH controls in any condition, while also showing a surprising ability to use VQ and pitch cues.

Acoustic salience in the evaluations of intelligibility and foreign accentedness of nonnative vowel production

The study investigates the relative weighting of spectral and temporal acoustic cues in native speakers’ (NS) perception of vowels produced by nonnative speakers (NNS). Acoustic measurements were taken of the spectral and temporal properties of vowels produced by Chinese L2 speakers of English, and by native speakers of American English and British English, who were recruited to pronounce monosyllabic words containing 18 monophthongs and diphthongs in English. In the perception experiment, 25 native English speakers (16 American and 9 British) provided evaluations of intelligibility and ratings of foreign accentedness of the non-native vowels. A correlation analysis was conducted between the NS perception results and the acoustic computation of the NNS production data. The results show that spectral properties of vowels are significantly related to both American and British speakers’ evaluation of English vowels produced by Chinese L2 speakers, whereas the temporal information has no significant correlation to NS perceptual evaluations. The correlation between acoustic measurements and perceptual evaluations confirms that the most significant acoustic cue of English vowels is spectral rather than temporal information in perception.

Perceptual weighting of acoustic cues for accommodating gender-related talker differences heard by listeners with normal hearing and with cochlear implants.

Listeners must accommodate acoustic differences between vocal tracts and speaking styles of conversation partners-a process called normalization or accommodation. This study explores what acoustic cues are used to make this perceptual adjustment by listeners with normal hearing or with cochlear implants, when the acoustic variability is related to the talker's gender. A continuum between /ʃ/ and /s/ was paired with naturally spoken vocalic contexts that were parametrically manipulated to vary by numerous cues for talker gender including fundamental frequency (F0), vocal tract length (formant spacing), and direct spectral contrast with the fricative. The goal was to examine relative contributions of these cues toward the tendency to have a lower-frequency acoustic boundary for fricatives spoken by men (found in numerous previous studies). Normal hearing listeners relied primarily on formant spacing and much less on F0. The CI listeners were individually variable, with the F0 cue emerging as the strongest cue on average.

Cue weighting in the perception of Tagalog stress

Relative importance of different acoustic cues in perceived prominence is language specific. In Tagalog, it has been argued that there is a lexical level stress, and a stressed syllable exhibits higher fundamental frequency, longer duration, and stronger intensity (Gonzales, 1970). Still, the relative weight of these cues has not been discussed in the prosodic literature. The purpose of the current study is to quantify the relative weighting of multiple acoustic cues in the perception of lexical stress in Tagalog. A forced-choice identification test was conducted with a disyllabic word /babad/. Each of the three acoustic cues in both syllables was manipulated in two levels, i.e., strong and weak, under fully crossed combinations of the cues. A total of sixty-four stimuli were tested in four sessions, and fifty-three native speakers of Tagalog participated in the test. The result of a generalized linear model using a binomial distribution revealed that the primary perceptual cue is duration. Longer duration was significantly associated with perceived prominence, and higher fundamental frequency to a lesser degree. However, intensity cues did not seem to play a significant role in stress perception in Tagalog.

Moving towards a bilingual baseline in second language phonetic research

Abstract This investigation compared adult sequential bilinguals and native speakers (NSs) with the intention of determining if bilinguals are an appropriate comparison group for second language (L2) learners in L2 phonetic research. To that end, 16 Spanish-English bilinguals were compared to 20 NSs of English on their perception and production of two English vowels. In perception, both groups had a similar category boundary and acoustic cue weighting. In production, both groups produced distinct vowels that were highly intelligible, although the bilinguals produced the phonemes closer together in the vowel space and had more variable performance than the NSs. The inspection of these two participant groups reveals that bilinguals have the ability to perceive and produce a difficult L2 phonemic contrast, with slight and inconsequential differences when compared to NSs. Thus, I argue that bilinguals who have acquired a target structure are an apt comparison group in L2 phonetic experiments.

Weighting of Amplitude and Formant Rise Time Cues by School-Aged Children: A Mismatch Negativity Study.

An important skill in the development of speech perception is to apply optimal weights to acoustic cues so that phonemic information is recovered from speech with minimum effort. Here, we investigated the development of acoustic cue weighting of amplitude rise time (ART) and formant rise time (FRT) cues in children as measured by mismatch negativity (MMN). Twelve adults and 36 children aged 6-12 years listened to a /ba/-/wa/ contrast in an oddball paradigm in which the standard stimulus had the ART and FRT cues of /ba/. In different blocks, the deviant stimulus had either the ART or FRT cues of /wa/. The results revealed that children younger than 10 years were sensitive to both ART and FRT cues whereas 10- to 12-year-old children and adults were sensitive only to FRT cues. Moreover, children younger than 10 years generated a positive mismatch response, whereas older children and adults generated MMN. These results suggest that preattentive adultlike weighting of ART and FRT cues is attained only by 10 years of age and accompanies the change from mismatch response to the more mature MMN response. https://doi.org/10.23641/asha.6207608.

An evidence accumulation model of acoustic cue weighting in vowel perception

Listeners rely on multiple acoustic cues to recognize any phoneme. The relative contribution of these cues to listeners׳ perception is typically inferred from listeners׳ categorization of sounds in a two-alternative forced-choice task. Here we advocate the use of an evidence accumulation model to analyze categorization as well as response time data from such cue weighting paradigms in terms of the processes that underlie the listeners׳ categorization. We tested 30 Dutch listeners on their categorization of speech sounds that varied between typical /ɑ/ and /aː/ in vowel quality (F1 and F2) and duration. Using the linear ballistic accumulator model, we found that the changes in spectral quality and duration lead to changes in the speed of information processing, and the effects were larger for spectral quality. In addition, for stimuli with atypical spectral information, listeners accumulate evidence faster for /ɑ/ compared to /aː/. Finally, longer durations of sounds did not produce longer estimates of perceptual encoding time. Our results demonstrate the utility of evidence accumulation models for learning about the latent processes that underlie phoneme categorization. The implications for current theory in speech perception as well as future directions for evidence accumulation models are discussed.

Talker variability effects on vocal emotion recognition in acoustic and simulated electric hearing.

Vocal emotion production varies across talkers. Effects of talker variability (i.e., same talker vs different talkers across trials) on vocal emotion recognition were tested in babble noise and with cochlear implant (CI) simulations in normal-hearing listeners. Results showed significant talker variability effects in noise but not with CI simulations, suggesting that the degree of talker variability effects on vocal emotion recognition may vary with listeners' weighting of acoustic cues for emotions (e.g., pitch and duration) and the availability of these cues in different listening conditions. Vocal emotion recognition significantly improved with higher signal-to-noise ratio and more vocoder channels.

Acoustic Cue Weighting by Adults with Cochlear Implants: A Mismatch Negativity Study.

Formant rise time (FRT) and amplitude rise time (ART) are acoustic cues that inform phonetic identity. FRT represents the rate of transition of the formant(s) to a steady state, while ART represents the rate at which the sound reaches its peak amplitude. Normal-hearing (NH) native English speakers weight FRT more than ART during the perceptual labeling of the /ba/-/wa/ contrast. This weighting strategy is reflected neurophysiologically in the magnitude of the mismatch negativity (MMN)-MMN is larger during the FRT than the ART distinction. The present study examined the neurophysiological basis of acoustic cue weighting in adult cochlear implant (CI) listeners using the MMN design. It was hypothesized that individuals with CIs who weight ART more in behavioral labeling (ART users) would show larger MMNs during the ART than the FRT contrast, and the opposite would be seen for FRT users. Electroencephalography was recorded while 20 adults with CIs listened passively to combinations of 3 synthetic speech stimuli: a /ba/ with /ba/-like FRT and ART; a /wa/ with /wa/-like FRT and ART; and a /ba/ stimulus with /ba/-like FRT and /wa/-like ART. The MMN response was elicited during the FRT contrast by having participants passively listen to a train of /wa/ stimuli interrupted occasionally by /ba/ stimuli, and vice versa. For the ART contrast, the same procedure was implemented using the /ba/ and /ba/ stimuli. Both ART and FRT users with CIs elicited MMNs that were equal in magnitudes during FRT and ART contrasts, with the exception that FRT users exhibited MMNs for ART and FRT contrasts that were temporally segregated. That is, their MMNs occurred significantly earlier during the ART contrast (~100 msec following sound onset) than during the FRT contrast (~200 msec). In contrast, the MMNs for ART users of both contrasts occurred later and were not significantly separable in time (~230 msec). Interestingly, this temporal segregation observed in FRT users is consistent with the MMN behavior in NH listeners. Results suggest that listeners with CIs who learn to classify phonemes based on formant dynamics, consistent with NH listeners, develop a strategy similar to NH listeners, in which the organization of the amplitude and spectral representations of phonemes in auditory memory are temporally segregated.

Acoustic cue weighting in the singleton vs geminate contrast in Lebanese Arabic: The case of fricative consonants

This paper is the first reported investigation of the role of non-temporal acoustic cues in the singleton-geminate contrast in Lebanese Arabic, alongside the more frequently reported temporal cues. The aim is to explore the extent to which singleton and geminate consonants show qualitative differences in a language where phonological length is prominent and where moraic structure governs segment timing and syllable weight. Twenty speakers (ten male, ten female) were recorded producing trochaic disyllables with medial singleton and geminate fricatives preceded by phonologically short and long vowels. The following acoustic measures were applied on the medial fricative and surrounding vowels: absolute duration; intensity; fundamental frequency; spectral peak and shape, dynamic amplitude, and voicing patterns of medial fricatives; and vowel quality and voice quality correlates of surrounding vowels. Discriminant analysis and receiver operating characteristics (ROC) curves were used to assess each acoustic cue's contribution to the singleton-geminate contrast. Classification rates of 89% and ROC curves with an area under the curve rate of 96% confirmed the major role played by temporal cues, with non-temporal cues contributing to the contrast but to a much lesser extent. These results confirm that the underlying contrast for gemination in Arabic is temporal, but highlight [+tense] (fortis) as a secondary feature.

Weighting of Acoustic Cues to a Manner Distinction by Children With and Without Hearing Loss.

Children must develop optimal perceptual weighting strategies for processing speech in their first language. Hearing loss can interfere with that development, especially if cochlear implants are required. The three goals of this study were to measure, for children with and without hearing loss: (a) cue weighting for a manner distinction, (b) sensitivity to those cues, and (c) real-world communication functions. One hundred and seven children (43 with normal hearing [NH], 17 with hearing aids [HAs], and 47 with cochlear implants [CIs]) performed several tasks: labeling of stimuli from /bɑ/-to-/wɑ/ continua varying in formant and amplitude rise time (FRT and ART), discrimination of ART, word recognition, and phonemic awareness. Children with hearing loss were less attentive overall to acoustic structure than children with NH. Children with CIs, but not those with HAs, weighted FRT less and ART more than children with NH. Sensitivity could not explain cue weighting. FRT cue weighting explained significant amounts of variability in word recognition and phonemic awareness; ART cue weighting did not. Signal degradation inhibits access to spectral structure for children with CIs, but cannot explain their delayed development of optimal weighting strategies. Auditory training could strengthen the weighting of spectral cues for children with CIs, thus aiding spoken language acquisition.

Acoustic Cues to Perception of Word Stress by English, Mandarin, and Russian Speakers

This study investigated how listeners' native language affects their weighting of acoustic cues (such as vowel quality, pitch, duration, and intensity) in the perception of contrastive word stress. Native speakers (N = 45) of typologically diverse languages (English, Russian, and Mandarin) performed a stress identification task on nonce disyllabic words with fully crossed combinations of each of the 4 cues in both syllables. The results revealed that although the vowel quality cue was the strongest cue for all groups of listeners, pitch was the second strongest cue for the English and the Mandarin listeners but was virtually disregarded by the Russian listeners. Duration and intensity cues were used by the Russian listeners to a significantly greater extent compared with the English and Mandarin participants. Compared with when cues were noncontrastive across syllables, cues were stronger when they were in the iambic contour than when they were in the trochaic contour. Although both English and Russian are stress languages and Mandarin is a tonal language, stress perception performance of the Mandarin listeners but not of the Russian listeners is more similar to that of the native English listeners, both in terms of weighting of the acoustic cues and the cues' relative strength in different word positions. The findings suggest that tuning of second-language prosodic perceptions is not entirely predictable by prosodic similarities across languages.

How listeners weight acoustic cues to intonational phrase boundaries.

The presence of an intonational phrase boundary is often marked by three major acoustic cues: pause, final lengthening, and pitch reset. The present study investigates how these three acoustic cues are weighted in the perception of intonational phrase boundaries in two experiments. Sentences that contained two intonational phrases with a critical boundary between them were used as the experimental stimuli. The roles of the three acoustic cues at the critical boundary were manipulated in five conditions. The first condition featured none of the acoustic cues. The following three conditions featured only one cue each: pause, final lengthening, and pitch reset, respectively. The fifth condition featured both pause duration and pre-final lengthening. A baseline condition was also included in which all three acoustic cues were preserved intact. Listeners were asked to detect the presence of the critical boundaries in Experiment 1 and judge the strength of the critical boundaries in Experiment 2. The results of both experiments showed that listeners used all three acoustic cues in the perception of prosodic boundaries. More importantly, these acoustic cues were weighted differently across the two experiments: Pause was a more powerful perceptual cue than both final lengthening and pitch reset, with the latter two cues perceptually equivalent; the effect of pause and the effects of the other two acoustic cues were not additive. These results suggest that the weighting of acoustic cues contributes significantly to the perceptual differences of intonational phrase boundary.