Effects Of Talker Variability Research Articles

Processing talker variability in semantic/associative priming: Does talker voice matter?

The effect of talker variability on lexical access is investigated using short-term semantic/associative priming experiments. Prime-target pairs, either semantically associated (e.g., king-queen) or unrelated (e.g., bell-queen), were spoken by the same or different male speakers. Two interstimulus intervals (ISI, 50 and 250 ms) were used to explore the time course of semantic/associative priming and voice specificity effects. Forty listeners completed a lexical decision task followed by a talker voice discrimination task on the same auditory stimuli. Results from the lexical decision task showed semantic/associative priming effects, although the magnitude of priming was unaffected by talker variability or ISI. Results from the talker voice discrimination task showed no priming effects, although different-talker trials elicited faster and more accurate responses. In comparison with previous results using a similar paradigm (Lee & Zhang, in press; Zhang & Lee, 2011), this set of data suggests that talker va...

Talker variability in spoken word recognition: Evidence from repetition priming

The effect of talker variability on the processing of spoken words is investigated using short-term repetition priming experiments. Prime-target pairs, either repeated (e.g., queen-queen) or unrelated (e.g., bell-queen), were produced by the same or different male speakers. Two interstimulus intervals (ISI, 50 and 250 ms) were used to explore the time course of repetition priming and voice specificity effects. The auditory stimuli were presented to 40 listeners, who completed a lexical decision task followed by a talker voice discrimination task. Results from the lexical decision task showed that the magnitude of priming was attenuated in the different-talker condition, indicating a talker variability effect on spoken word recognition. In contrast, the talker variability effect on priming did not differ between the two ISIs. Talker voice discrimination was faster and more accurate for nonword targets, but not for word targets, indicating a lexical status effect on voice discrimination. Taken together, these results suggest that talker variability affects recognition of spoken words, and that the effect cannot be simply attributed to non-lexical voice discrimination.

Role of serial order in the impact of talker variability on short-term memory: testing a perceptual organization-based account

In two experiments, we examined the impact of the degree of match between sequential auditory perceptual organization processes and the demands of a short-term memory task (memory for order vs. item information). When a spoken sequence of digits was presented so as to promote its perceptual partitioning into two distinct streams by conveying it in alternating female (F) and male (M) voices (FMFMFMFM)--thereby disturbing the perception of true temporal order--recall of item order was greatly impaired (as compared to recall of item identity). Moreover, an order error type consistent with the formation of voice-based streams was committed more quickly in the alternating-voice condition (Exp. 1). In contrast, when the perceptual organization of the sequence mapped well onto an optimal two-group serial rehearsal strategy--by presenting the two voices in discrete clusters (FFFFMMMM)--order, but not item, recall was enhanced (Exp. 2). The results are consistent with the view that the degree of compatibility between perceptual and deliberate sequencing processes is a key determinant of serial short-term memory performance. Alternative accounts of talker variability effects in short-term memory, based on the concept of a dedicated phonological short-term store and a capacity-limited focus of attention, are also reviewed.

Talker variability in lexical access: Evidence from semantic priming.

It is usually assumed that lexical representations are abstract and devoid of detailed information about various sources of acoustic variability. This assumption is evaluated in this study by examining the effect of talker variability on the access to word meaning in a short‐term semantic priming experiment. Prime‐target pairs that were semantically related (e.g., king‐queen) or unrelated (e.g., bell‐queen) were produced by the same talker or different talkers. Two interstimulus intervals (50 and 250 ms) were used between the prime and target to explore the time course of semantic priming. The auditory stimuli were presented to 60 listeners, whose task was to judge whether the target was a word or nonword item in English. It was hypothesized that a change in talker between the prime and target would influence the magnitude of semantic facilitation. Analysis of response accuracy and reaction time showed that the magnitude of semantic priming was attenuated in the different‐talker condition, although the effect was obtained only for targets produced by the female speaker. There were no effects involving different interstimulus intervals. These results provided partial evidence that talker variability is encoded in lexical representations and affects lexical access.

Effects of Talker Variability on Speech Recognition of Normal-Hearing Listeners for Korean Speech Audiometry

The purpose of this study was to examine effects of talker variability manipulated by the number of target talkers (two- versus multitalker) on the speech recognition results of Korean Speech Audiometry. Korean Speech Audiometry (KSA, www.kops.co.kr) included three types of the speech test materials (one-, two-syllable words, and sentences), and was recorded digitally in CDs by either a male or female talker. Given that some researchers have reported a significant effect of talker variability on speech recognition accuracy, we recorded all the speech materials in CDs by 20 talkers (10 male and 10 female). The effect of talker variability was then determined by comparing speech recognition performances of 5 young normal-hearing listeners by two-talker (in KSA CD) versus 20-talker conditions from -5 to 40 dB HL in 5 dB steps. The results showed that speech recognition accuracy of young normal-hearing listeners did not significantly differ in conditions for each of the three speech materials at each presentation level. This indicated important clinical implications of CD materials in KSA for the speech audiometric tests. KEY WORDS：Korean speech audiometry·Speech recognition·Talker variability.

Perceptual expectations, attention, and speech recognition.

Research has demonstrated substantial plasticity in the adult speech perceiver. When listeners receive feedback about the classification of a speech signal, this feedback can shape attention affecting phoneme perception. This demonstrates that it is possible to shape perceptual attention prospectively changing subsequent speech perception. These changes can also reduce the cognitive load of speech perception. The effect of expectations on speech perception has been reported for a wide range of studies from sinewave speech perception to phonetic categorization and effects of talker variability. Neural changes occurring during learning and the neural effects of expectations both appear to involve regions of motor cortex implicated in speech production. These neural changes suggest a model of speech perception similar to analysis-by-synthesis in which sensory processes are tuned by activity within the speech motor system. Although such sensory-motor interactions have been implicated in speech perception due to coarticulation and the encoding of speech into sound, the role of expectations in speech perception may extend beyond segmental perception. We consider evidence that the interpretation of prosodic signals also depends on perceptual expectations, suggesting that the role of expectations may be to constrain recognition given the many-to-many relationship that holds broadly in speech.

Effects of talker and token variability on perceptual learning of dialect categories.

Dialect classification is difficult for naive listeners, but perceptual learning tasks using sentence-length utterances have been shown to produce modest improvements in performance. The goal of the current study was to explore perceptual learning by naive listeners in a speeded dialect classification task with shorter, word-length utterances. In a series of experiments, participants were trained in a two-alternative forced-choice speeded dialect classification task (Cleveland vs. Cincinnati) with feedback and were then tested in the same task with novel talkers and novel words without feedback to assess learning. Variability in the stimulus materials in the training phase, including the number of talkers from each dialect and the number of different tokens produced by each talker, was manipulated across experiments to determine how variation in the input affected perceptual learning of dialect categories. The results revealed that training materials consisting of utterances produced by multiple different talkers from each dialect with multiple different tokens produced by each talker led to a significant improvement in dialect classification performance compared to a baseline condition without training. These findings suggest that dialect classification performance can improve with training on short, word-length utterances, but that robust dialect category learning requires high variability stimulus materials.

Effects of Talker Variability on Vowel Recognition in Cochlear Implants

To investigate the effects of talker variability on vowel recognition by cochlear implant (CI) users and by normal-hearing (NH) participants listening to 4-channel acoustic CI simulations. CI users were tested with their clinically assigned speech processors. For NH participants, 3 CI processors were simulated, using different combinations of carrier type and temporal envelope cutoff frequency (noise band/160 Hz, sine wave/160 Hz, and sine wave/20 Hz). Vowel recognition was measured for 4 talkers, presented in either a single-talker context (1 talker per test block) or a multi-talker context (4 talkers per test block). CI users' vowel recognition was significantly poorer in the multi-talker context than in the single-talker context. When noise-band carriers were used in the simulations, NH performance was not significantly affected by talker variability. However, when sine-wave carriers were used in the simulations, NH performance was significantly affected by talker variability in both envelope filter conditions. Because fundamental frequency was not preserved by the 20-Hz envelope filter and only partially preserved by the 160-Hz envelope filter, both spectral and temporal cues contributed to the talker variability effects observed with sine-wave carriers. Similarly, spectral and temporal cues may have contributed to the talker variability effects observed with CI participants.

Effects of open-set and closed-set task demands on spoken word recognition.

Closed-set tests of spoken word recognition are frequently used in clinical settings to assess the speech discrimination skills of hearing-impaired listeners, particularly children. Speech scientists have reported robust effects of lexical competition and talker variability in open-set tasks but not closed-set tasks, suggesting that closed-set tests of spoken word recognition may not be valid assessments of speech recognition skills. The goal of the current study was to explore some of the task demands that might account for this fundamental difference between open-set and closed-set tasks. In a series of four experiments, we manipulated the number and nature of the response alternatives. Results revealed that as more highly confusable foils were added to the response alternatives, lexical competition and talker variability effects emerged in closed-set tests of spoken word recognition. These results demonstrate a close coupling between task demands and lexical competition effects in lexical access and spoken word recognition processes.

Language learning

Language learning

Effects of talker variability on vowel recognition by cochlear implant users and normal-hearing subjects listening to cochlear implant simulations

Different talker characteristics can significantly affect speech recognition, especially under conditions of reduced spectral resolution. In the current study, single- and multi-talker vowel recognition was tested with both cochlear implant (CI) patients and normal-hearing (NH) subjects listening to CI simulations. CI users were tested with their everyday processors. NH subjects were tested using four-channel acoustic processors in which the envelope cutoff frequency (20, 160 Hz) and the carrier band (noise-band, sine-wave) conditions were varied. Results showed that CI users’ single-talker vowel recognition was significantly better than multi-talker recognition. Among the simulations, both single- and multi-talker vowel recognition was best with the 160 Hz/sine-wave processor. Also, single-talker performance was significantly better than multi-talker performance only with the 160 Hz/sine-wave processor; there was no difference between single- and multi-talker recognition with the 20 Hz/sine-wave or noise-band processor. While the effects of talker variability were less for the 20 Hz/sine-wave and noise-band processors, overall vowel recognition was also significantly lower. Listeners’ sensitivity to talker variability may indicate their ability to register the relative vowel space for individual talkers. Without sensitivity to talker variability, multi-talker vowel space may collapse, causing cross-talker differences to be confused with phonetic differences. [Research is supported by NIDCD.]

Effects of Talker Variability on Perceptual Learning of Dialects

Two groups of listeners learned to categorize a set of unfamiliar talkers by dialect region using sentences selected from the TIMIT speech corpus. One group learned to categorize a single talker from each of six American English dialect regions. A second group learned to categorize three talkers from each dialect region. Following training, both groups were asked to categorize new talkers using the same categorization task. While the single-talker group was more accurate during initial training and test phases when familiar talkers produced the sentences, the three-talker group performed better on the generalization task with unfamiliar talkers. This cross-over effect in dialect categorization suggests that while talker variation during initial perceptual learning leads to more difficult learning of specific exemplars, exposure to intertalker variability facilitates robust perceptual learning and promotes better categorization performance of unfamiliar talkers. The results suggest that listeners encode and use acoustic-phonetic variability in speech to reliably perceive the dialect of unfamiliar talkers.

Acquisition of second-language speech: Effects of visual cues, context, and talker variability

The influence of a talker's face (e.g., articulatory gestures) and voice, vocalic context, and word position were investigated in the training of Japanese and Korean English as a second language learners to identify American English /[invertedr]/ and /l/. In the pretest–posttest design, an identification paradigm assessed the effects of 3 weeks of training using multiple natural exemplars on videotape. Word position, adjacent vowel, and training type (auditory–visual [AV] vs. auditory only; multiple vs. single talker for Koreans) were independent variables. Findings revealed significant effects of training type (greater improvement with AV), talker, word position, and vowel. Identification accuracy generalized successfully to novel stimuli and a new talker. Transfer to significant production improvement was also noted. These findings are compatible with episodic models for the encoding of speech in memory.

Applied linguistics

04–669 Hardison, Debra M. (Michigan State U., USA; Email: hardiso2@msu.edu). Acquisition of second-language speech: effects of visual cues, context, and talker variability. Applied Psycholinguistics (Cambridge, UK), 24, 4 (2003), 495–522.04–670 Hirst, Elizabeth (Griffith U., Queensland, Australia; Email: e.hirst@griffith.edu.au) Diverse voices in a second language classroom: burlesque, parody and mimicry. Language and Education (Clevedon, UK), 17, 3 (2003), 174–191.04–671 Matsumura, Shoichi (Ryukoku U., Japan). Modelling the relationships among interlanguage pragmatic development, L2 proficiency, and exposure to L2. Applied Linguistics (Oxford, UK), 24, 4 (2003), 465–491.04–672 de Mattos Pimenta Parente, Maria Alice and Geiger, Lucienne (Rio Grande do Sul Federal U., Brazil) and Dunbar, Harriet and Nespoulous, Jean-Luc. The role of phonological loop components on children's story recall during the first years of schooling. Revue Parole (Mons, Belgium), 25/26 (2003), 45–74.

Effects of response format on speech intelligibility in noise: Results obtained from open-set, closed-set, and delayed response tasks

Many word recognition studies over the last 40 years have used forced-choice closed-set tasks, based on the assumption that closed-set and open-set tasks differ only in the level of chance performance. However, Sommers, Kirk, and Pisoni (1997) found that lexical competition and talker variability produce robust effects on performance only in open-set tasks, suggesting fundamental differences in the task demands and processing strategies between open- and closed-set tasks. In the present study, listeners were asked to recognize spoken words degraded by a bit-flipping algorithm in three response formats: open-set, closed-set ‘‘before,’’ and closed-set ‘‘after.’’ In the closed-set ‘‘before’’ condition, the six response alternatives were presented 1 s prior to the onset of the auditory signal. In the closed-set ‘‘after’’ condition, the response alternatives were presented 1 s after the auditory signal. Results revealed significant effects of lexical competition and talker variability only in the open-set task. These findings suggest that even a delay of 1 s is not adequate to induce the task demands observed in open-set word recognition tests. [Work supported by NIH.].

Multiple talker effects in auditory–visual speech perception among older adults

Talker variability effects have been shown for speech stimuli presented auditorily to young adult and older adult participants. Recent investigations suggest that similar variability is seen among young adults for auditory–visual congruent and discrepant stimuli. Older adults are reported to be at a disadvantage for processing information spoken by multiple talkers. Some investigators have suggested that perceptually demanding conditions, such as listening in noise may be more difficult for older listeners. In the current investigation, talker variability effects for CV syllables were examined in multiple modalities visual-only, auditory-only, and auditory–visual for older listeners. Auditory–visual presentations were of two types: congruent [auditory and visual were of the same token —/visual bi and auditory bi/] or disparate [/visual gi and auditory bi/]. The disparate condition has elicited the McGurk effect, in which listeners may report a fused response that is neither the auditory or the visual component of the stimulus. The talkers were 11 individuals with known equivalent auditory intelligibility. Consistent with previous work, individual older listeners varied considerably in their overall perceptions, from complete fusion for all talkers to almost no fusion for any talker. Further, older listeners demonstrated poorer performance in comparison to younger adults in the multitalker condition.

Lexical and talker effects on word recognition among native and non-native listeners with normal and impaired hearing.

Evidence suggests that word recognition depends on numerous talker-, listener-, and stimulus-related characteristics. The current study examined the effects of talker variability and lexical difficulty on spoken-word recognition among four groups of listeners: native listeners with normal hearing or hearing impairment (moderate sensorineural hearing loss) and non-native listeners with normal hearing or hearing impairment. The ability of listeners to accommodate trial-to-trial variations in talkers' voice was assessed by comparing recognition scores for a single-talker condition to those obtained in a multiple-talker condition. Lexical difficulty was assessed by comparing word-recognition performance between lexically "easy" and "hard" words as determined by frequency of occurrence in language and the structural characteristics of similarity neighborhoods formalized in the Neighborhood Activation Model. An up-down adaptive procedure was used to determine the sound pressure level for 50% performance. Non-native listeners in both normal-hearing and hearing-impaired groups required greater intensity for equal intelligibility than the native normal-hearing and hearing-impaired listeners. Results, however, showed significant effects of talker variability and lexical difficulty for the four groups. Structural equation modeling demonstrated that an audibility factor accounts for 2-3 times more variance in performance than does a linguistic-familiarity factor. However, the linguistic-familiarity factor is also essential to the model fit. The results demonstrated effects of talker variability and lexical difficulty on word recognition for both native and nonnative listeners with normal or impaired hearing. The results indicate that linguistic and indexical factors should be considered in the development of speech-recognition tests.

Effects of lexical and talker variability factors on spoken word recognition in native and non-native, normal and hearing-impaired listeners

The effects of lexical difficulty and talker variability on word recognition were examined in four groups of listeners: native English/normal hearing; native English/hearing impaired; non-native English/normal hearing; and non-native English/hearing impaired (hearing level matched to the native hearing impaired). Lexical difficulty was measured by the difference in performance to 75 lexically ‘‘easy’’ and ‘‘hard’’ words based on word frequency and Neighborhood Activation Theory [Luce and Pisoni (1998)]. The effect of talker variability was measured by the difference in performance between single and multiple talker (nine talkers) conditions. The familiarity of the 150 words was rated on a seven-point scale. An up–down adaptive procedure was used to determine the sound pressure level for 50% performance. Non-native listeners in both normal and hearing-impaired groups required a greater intensity for equal intelligibility than for the comparative native normal and hearing-impaired listeners. Results, however, showed significant effects of lexical difficulty and talker variability in all four groups. Structural equation modeling demonstrated that an auditory factor estimated by pure tone average, etc., accounts for four times more variance to performance than does a linguistic fluency factor measured by word familiarity ratings and native versus non-native status, however, the linguistic fluency factor is also essential to the model fit.

The role of talker-specific information in word segmentation by infants.

Infants' representations of the sound patterns of words were explored by examining the effects of talker variability on the recognition of words in fluent speech. Infants were familiarized with isolated words (e.g., cup and dog) from 1 talker and then heard 4 passages produced by another talker, 2 of which included the familiarized words. At 7.5 months of age, infants attended longer to passages with the familiar words for materials produced by 2 female talkers or 2 male talkers but not for materials by a male and a female talker. These findings suggest a strong role for talker-voice similarity in infants' ability to generalize word tokens. By 10.5 months, infants could generalize different instances of the same word across talkers of the opposite sex. One implication of the present results is that infants' initial representations of the sound structure of words not only include phonetic information but also indexical properties relating to the vocal characteristics of particular talkers.

Talker variability effects in auditory-visual speech perception

Talker variability effects have been demonstrated for many aspects of syllable, word, and sentence recognition for stimuli presented in the auditory-only modality. In the current investigation, talker variability effects were examined in multiple modalities—visual-only, auditory-only, and auditory-visual. Auditory-visual presentations were of two types: consonant [auditory and visual were of the same token—/visual bi and auditory bi/] or disparate [/visual gi and auditory bi or visual bi and auditory gi/]. The disparate condition has elicited ‘‘the McGurk effect,’’ in which listeners may report a fused response that is neither the auditory or the visual component of the stimulus. Eleven talkers (five male and six female) of varying cultural backgrounds were videotaped. Their productions of CV syllables were presented to adult listeners who reported their percepts. Individual talkers elicited different degrees of syllable fusion among listeners, despite their equivalent auditory intelligibility. In addition, individual listeners varied considerably in their overall perceptions, from complete fusion for all talkers to almost no fusion for any talker. Results suggest that listeners may employ different types of processing strategies for bimodal stimuli. [Research supported by NIDCD.]