Pairs Of Talkers Research Articles

The effects of delay on task-based interactive conversation

Previous studies have found that, in the presence of noise, the distribution of floor transfer offsets (FTO) broadens and shifts to the right, and it has been suggested that this is due to increased listening effort. The present study investigates if speakers are sensitive to the timing of the start of a partner's turn during interactive conversation. By manipulating the delay on the channel between two talkers on a turn-by-turn basis, the floor transfer offset (FTO) distribution can be modified to simulate what has been observed in more challenging conversational settings. Talkers were seated in different rooms but could communicate via headset microphones and headphones with gains fixed such that the levels would simulate the two talkers sitting in the same room. Conversations where pairs of talkers solved the DiapixUK spot-the-difference task were conducted in both quiet and noise, both with and without added delay. Measures of speech production (e.g., speech level, articulation rate, etc.) and conversation behavior (FTO, turn length, etc.) are compared across the conditions.

Lexical effects on talker discrimination in adult cochlear implant usersa).

The lexical and phonological content of an utterance impacts the processing of talker-specific details in normal-hearing (NH) listeners. Adult cochlear implant (CI) users demonstrate difficulties in talker discrimination, particularly for same-gender talker pairs, which may alter the reliance on lexical information in talker discrimination. The current study examined the effect of lexical content on talker discrimination in 24 adult CI users. In a remote AX talker discrimination task, word pairs-produced either by the same talker (ST) or different talkers with the same (DT-SG) or mixed genders (DT-MG)-were either lexically easy (high frequency, low neighborhood density) or lexically hard (low frequency, high neighborhood density). The task was completed in quiet and multi-talker babble (MTB). Results showed an effect of lexical difficulty on talker discrimination, for same-gender talker pairs in both quiet and MTB. CI users showed greater sensitivity in quiet as well as less response bias in both quiet and MTB for lexically easy words compared to lexically hard words. These results suggest that CI users make use of lexical content in same-gender talker discrimination, providing evidence for the contribution of linguistic information to the processing of degraded talker information by adult CI users.

Generalized perceptual adaptation to second-language speech: Variability, similarity, and intelligibilitya).

Recent work on perceptual learning for speech has suggested that while high-variability training typically results in generalization, low-variability exposure can sometimes be sufficient for cross-talker generalization. We tested predictions of a similarity-based account, according to which, generalization depends on training-test talker similarity rather than on exposure to variability. We compared perceptual adaptation to second-language (L2) speech following single- or multiple-talker training with a round-robin design in which four L2 English talkers from four different first-language (L1) backgrounds served as both training and test talkers. After exposure to 60 L2 English sentences in one training session, cross-talker/cross-accent generalization was possible (but not guaranteed) following either multiple- or single-talker training with variation across training-test talker pairings. Contrary to predictions of the similarity-based account, adaptation was not consistently better for identical than for mismatched training-test talker pairings, and generalization patterns were asymmetrical across training-test talker pairs. Acoustic analyses also revealed a dissociation between phonetic similarity and cross-talker/cross-accent generalization. Notably, variation in adaptation and generalization related to variation in training phase intelligibility. Together with prior evidence, these data suggest that perceptual learning for speech may benefit from some combination of exposure to talker variability, training-test similarity, and high training phase intelligibility.

Clear speech adaptations in spontaneous speech produced by young and older adults.

The study investigated the speech adaptations by older adults (OA) with and without age-related hearing loss made to communicate effectively in challenging communicative conditions. Acoustic analyses were carried out on spontaneous speech produced during a problem-solving task (diapix) carried out by talker pairs in different listening conditions. There were 83 talkers of Southern British English. Fifty-seven talkers were OAs aged 65-84, 30 older adults with normal hearing (OANH), and 27 older adults with hearing loss (OAHL) [mean pure tone average (PTA) 0.250-4 kHz: 27.7 dB HL]. Twenty-six talkers were younger adults (YA) aged 18-26 with normal hearing. Participants were recorded while completing the diapix task with a conversational partner (YA of the same sex) when (a) both talkers heard normally (NORM), (b) the partner had a simulated hearing loss, and (c) both talkers heard babble noise. Irrespective of hearing status, there were age-related differences in some acoustic characteristics of YA and OA speech produced in NORM, most likely linked to physiological factors. In challenging conditions, while OANH talkers typically patterned with YA talkers, OAHL talkers made adaptations more consistent with an increase in vocal effort. The study suggests that even mild presbycusis in healthy OAs can affect the speech adaptations made to maintain effective communication.

Nonnative Accent Discrimination with Words and Sentences

Background: Accent detection studies have shown native listeners to be highly sensitive to the presence of nonnative accents. This study examined the robustness of this sensitivity. Methods: We evaluated listeners' accent discrimination performance when presented with a stimulus set consisting of multiple nonnative accents, as well as words and sentences that were unique in each trial. Listeners heard pairs of talkers reading the same word or sentence and indicated whether the talkers' native languages were the same or different. Talkers included two native talkers and six nonnative talkers from three native language backgrounds. Results: Listeners were highly sensitive to the difference between native and nonnative accents, confirming earlier findings, but were much less sensitive to the difference between two nonnative accents. Furthermore, while stimulus length affected listeners' sensitivity to the difference between native and nonnative accents, this factor had a minimal effect on their sensitivity to the difference between two nonnative accents. Conclusion: The findings suggest that task and stimulus characteristics have a significant effect on the degree of sensitivity to nonnative accents.

Clear speech adaptations across the lifespan

Talkers need to be able to alter their speech production in order to communicate effectively in conditions in which there are acoustic or linguistic barriers to communication. The clear speaking styles that result from such adaptations have been well documented, but mostly for young adult talkers. As a skilled aspect of speech production, the ability to make such adaptations may develop late during acquisition and be affected by reduced motor or cognitive control in older talkers. In a series of studies, we are investigating how speech adaptations in challenging communicative conditions change across the lifespan: in children aged 9 to 15 years, in young adults, in older adults aged 65 and above. In all three studies, recordings were made while talker pairs complete a cooperative problem-solving task (diapix) when communication was easy or when a communication barrier was placed on one talker. Acoustic analyses have shown adaptations to speaking rate, intensity, fundamental frequency characteristics, vowel formant space. While young adults seem adept at making adaptations that are well suited to overcome the specific interference experienced by their interlocutors, younger talkers appear to make less nuanced adaptations. We will discuss factors affecting such speech adaptations across the lifespan.

Foreign-accent discrimination with words and sentences

Native listeners can detect a foreign accent in very short stimuli; however, foreign-accent detection is more accurate with longer stimuli (Park, 2008; Flege, 1984). The current study investigated native listeners’ sensitivity to the characteristics that differentiate between accents—both foreign versus native accents and one foreign accent versus another—in words and sentences. Listeners heard pairs of talkers reading the same word or sentence and indicated whether the talkers had the same or different native language backgrounds. Talkers included two native talkers (Midland dialect) and six nonnative talkers from three native language backgrounds (German, Mandarin, and Korean). Sensitivity varied significantly depending on the specific accent pairings and stimulus type. Listeners were most sensitive when the talker pair included a native talker, but could detect the difference between two nonnative accents. Furthermore, listeners were generally more sensitive with sentences than with words. However, for one nonnative pairing, listeners exhibited higher sensitivity with words; for another, listeners’ sensitivity did not differ significantly across stimulus types. These results suggest that accent discrimination is not simply influenced by stimulus length. Sentences may provide listeners with opportunities to perceive similarities between nonnative talkers, which are not salient in single words. [Work supported by NIDCD T32 DC00012.]

Strategies adopted by talkers faced with fluctuating and competing-speech maskers

Studying how interlocutors exchange information efficiently during conversations in less-than-ideal acoustic conditions promises to both further the understanding of links between perception and production and inform the design of human-computer dialogue systems. The current study explored how interlocutors' speech changes in the presence of fluctuating noise. Pairs of talkers were recorded while solving puzzles cooperatively in quiet and with modulated-noise or competing speech maskers whose silent intervals were manipulated to produce either temporally sparse or dense maskers. Talkers responded to masked conditions by both increasing the amount of speech produced and locally changing their speech activity patterns, resulting in a net reduction in the proportion of speech in temporal overlap with the maskers, with larger relative reductions for sparse maskers. An analysis of talker activity in the vicinity of masker onset and offset events showed a significant reduction in onsets following masker onsets, and a similar increase in onsets following masker offsets. These findings demonstrate that talkers are sensitive to masking noise and respond to its fluctuations by adopting a "wait-and-talk" strategy.

Phonetic convergence, communicative efficiency, and language distance

Many English conversations across the globe today involve talkers with different language experiences. Here we show that, while language barriers challenge communicative efficiency, the detrimental effect of language distance may be mitigated by phonetic convergence. We analyzed a corpus of 42 conversations in which talker pairs solved a spot-the-difference puzzle by verbally comparing two scenes only one of which was visible to each talker (“diapix” task). Language distance was varied by pairing talkers who either matched or mismatched in language background and in native/nonnative status relative to the target language. Communicative efficiency was measured by task-completion-time and word type-to-token ratio. Phonetic convergence was assessed by perceptual similarity tests in which listeners (n = 161) compared samples from one talker’s speech to samples from his/her partner’s speech from either early or late portions of the conversation. In this test, greater similarity for late than early samples indicates convergence. Results showed a negative correlation between language distance and communicative efficiency, a negative correlation between language distance and phonetic convergence, and a mitigating effect of phonetic convergence on the negative correlation between language distance and communicative efficiency. This suggests that convergence may be an effective mechanism for overcoming the detrimental effects of a language barrier.

Phonetic convergence in spontaneous conversations as a function of interlocutor language distance

This study explores phonetic convergence during conversations between pairs of talkers with varying language distance. Specifically, we examined conversations within two native English talkers and within two native Korean talkers who had either the same or different regional dialects, and between native and nonnative talkers of English. To measure phonetic convergence, an independent group of listeners judged the similarity of utterance samples from each talker through an XAB perception test, in which X was a sample of one talker's speech and A and B were samples from the other talker at either early or late portions of the conversation. The results showed greater convergence for same-dialect pairs than for either the different-dialect pairs or the different-L1 pairs. These results generally support the hypothesis that there is a relationship between phonetic convergence and interlocutor language distance. We interpret this pattern as suggesting that phonetic convergence between talker pairs that vary in the degree of their initial language alignment may be dynamically mediated by two parallel mechanisms: the need for intelligibility and the extra demands of nonnative speech production and perception.

Conversational role influences speech imitation

This study assessed the impact of a conscious imitation goal on phonetic convergence during conversational interaction. Twelve pairs of unacquainted talkers participated in a conversational task designed to elicit between-talker repetitions of the same lexical items. To assess the degree to which the talkers exhibited phonetic convergence during the conversational task, these repetitions were used to elicit perceptual similarity judgments provided by separate sets of listeners. In addition, perceptual measures of phonetic convergence were compared with measures of articulation rates and vowel formants. The sex of the pair of talkers and a talker's role influenced the degree of phonetic convergence, and perceptual judgments of phonetic convergence were not consistently related to individual acoustic-phonetic attributes. Therefore, even with a conscious imitative goal, situational factors were shown to retain a strong influence on phonetic form in conversational interaction.

Perceptual similarity of unfamiliar regional dialects.

Linguistic experience has been shown to influence the perception of regional dialect variation. Recent studies have found that the amount and type of experience with regional dialect variation affect performance in identifying or categorizing regional dialects. Experience also shapes the perceived similarity among regional varieties. To examine the effect of familiarity on the perceived similarity of regional dialects, a paired comparison perceptual similarity rating task was carried out with a group of unfamiliar regional dialects. Native speakers of American English made explicit judgments about the similarity of unfamiliar talkers from the United Kingdom and Ireland based on the regional dialect. Results show that listeners judged the regional dialects of pairs of talkers from the same dialect region as more similar than those of pairs of talkers from different dialect regions. A multidimensional scaling analysis revealed two dimensions of perceptual dialect similarity, both reflecting the geographic location of the cities of origins of the talkers (north versus south and east versus west). Thus, despite being unfamiliar with the regional dialects in the study, listeners were able to use dialect‐specific differences in the acoustic signal to make judgments on the perceptual similarity of talkers based on regional dialect.

Transfer of Auditory Perceptual Learning with Spectrally Reduced Speech to Speech and Nonspeech Tasks: Implications for Cochlear Implants

The objective of this study was to assess whether training on speech processed with an eight-channel noise vocoder to simulate the output of a cochlear implant would produce transfer of auditory perceptual learning to the recognition of nonspeech environmental sounds, the identification of speaker gender, and the discrimination of talkers by voice. Twenty-four normal-hearing subjects were trained to transcribe meaningful English sentences processed with a noise vocoder simulation of a cochlear implant. An additional 24 subjects served as an untrained control group and transcribed the same sentences in their unprocessed form. All subjects completed pre- and post-test sessions in which they transcribed vocoded sentences to provide an assessment of training efficacy. Transfer of perceptual learning was assessed using a series of closed set, nonlinguistic tasks: subjects identified talker gender, discriminated the identity of pairs of talkers, and identified ecologically significant environmental sounds from a closed set of alternatives. Although both groups of subjects showed significant pre- to post-test improvements, subjects who transcribed vocoded sentences during training performed significantly better at post-test than those in the control group. Both groups performed equally well on gender identification and talker discrimination. Subjects who received explicit training on the vocoded sentences, however, performed significantly better on environmental sound identification than the untrained subjects. Moreover, across both groups, pre-test speech performance and, to a higher degree, post-test speech performance, were significantly correlated with environmental sound identification. For both groups, environmental sounds that were characterized as having more salient temporal information were identified more often than environmental sounds that were characterized as having more salient spectral information. Listeners trained to identify noise-vocoded sentences showed evidence of transfer of perceptual learning to the identification of environmental sounds. In addition, the correlation between environmental sound identification and sentence transcription indicates that subjects who were better able to use the degraded acoustic information to identify the environmental sounds were also better able to transcribe the linguistic content of novel sentences. Both trained and untrained groups performed equally well ( approximately 75% correct) on the gender-identification task, indicating that training did not have an effect on the ability to identify the gender of talkers. Although better than chance, performance on the talker discrimination task was poor overall ( approximately 55%), suggesting that either explicit training is required to discriminate talkers' voices reliably or that additional information (perhaps spectral in nature) not present in the vocoded speech is required to excel in such tasks. Taken together, the results suggest that although transfer of auditory perceptual learning with spectrally degraded speech does occur, explicit task-specific training may be necessary for tasks that cannot rely on temporal information alone.

Talker intelligibility differences in cochlear implant listeners

People vary in the intelligibility of their speech. This study investigated whether across-talker intelligibility differences observed in normally-hearing listeners are also found in cochlear implant (CI) users. Speech perception for male, female, and child pairs of talkers differing in intelligibility was assessed with actual and simulated CI processing and in normal hearing. While overall speech recognition was, as expected, poorer for CI users, differences in intelligibility across talkers were consistent across all listener groups. This suggests that the primary determinants of intelligibility differences are preserved in the CI-processed signal, though no single critical acoustic property could be identified.

The evolutionary social psychology of off-record indirect speech acts

This paper proposes a new analysis of indirect speech in the framework of game theory, social psychology, and evolutionary psychology. It builds on the theory of Grice, which tries to ground indirect speech in pure rationality (the demands of efficient communication between two cooperating agents) and on the Politeness Theory of Brown and Levinson, who proposed that people cooperate not just in exchanging data but in saving face (both the speaker's and the hearer's). I suggest that these theories need to be supplemented because they assume that people in conversation always cooperate. A reflection on how a pair of talkers may have goals that conflict as well as coincide requires an examination of the game-theoretic logic of plausible denial, both in legal contexts, where people's words may be held against them, and in everyday life, where the sanctions are social rather than judicial. This in turn requires a theory of the distinct kinds of relationships that make up human social life, a consideration of a new role for common knowledge in the use of indirect speech, and ultimately the paradox of rational ignorance, where we choose not to know something relevant to our interests.

On phonetic convergence during conversational interaction

Following research that found imitation in single-word shadowing, this study examines the degree to which interacting talkers increase similarity in phonetic repertoire during conversational interaction. Between-talker repetitions of the same lexical items produced in a conversational task were examined for phonetic convergence by asking a separate set of listeners to detect similarity in pronunciation across items in a perceptual task. In general, a listener judged a repeated item spoken by one talker in the task to be more similar to a sample production spoken by the talker's partner than corresponding pre- and postinteraction utterances. Both the role of a participant in the task and the sex of the pair of talkers affected the degree of convergence. These results suggest that talkers in conversational settings are susceptible to phonetic convergence, which can mark nonlinguistic functions in social discourse and can form the basis for phenomena such as accent change and dialect formation.

The DCIEM Map Task Corpus: Spontaneous dialogue under sleep deprivation and drug treatment

This paper describes a resource designed for the general study of spontaneous speech under the stress of sleep deprivation. It is a corpus of 216 unscripted task-oriented dialogues produced by normal adults in the course of a major sleep deprivation study. The study itself examined continuous task performance through baseline, sleepless and recovery periods by groups treated with placebo or one of two drugs (Modafinil, d-amphetamine) reputed to counter the effects of sleep deprivation. The dialogues were all produced while carrying out the route communication task used in the HCRC Map Task Corpus. Pairs of talkers collaborated to reproduce on one partner's schematic map a route preprinted on the other's. Controlled differences between the maps and use of labelled imaginary locations limit genre, vocabulary and effects of real-world knowledge. The designs for the construction of maps and the allocation of subjects to maps make the corpus a controlled elicitation experiment. Each talker participated in 12 dialogues over the course of the study. Preliminary examinations of dialogue length and task performance measures indicate effects of drug treatment, sleep deprivation and number of conversational partners. The corpus is available to researchers interested in all levels of speech and dialogue analysis, in both normal and stressed conditions.

A comparison of maskers on spatially separated competing messages

The intelligibility of simultaneous speech signals from pairs of talkers was improved with spatial separation of talkers using synthetic means. The simultaneous speech signals of the talkers, male versus male, female versus female, and male versus female, were separated by 0, 22, 44, 90, 134, and 180 deg. A simple left–right (180-deg) signal separation condition was also measured. Four listeners responded to both diotic and spatially separated presentations over headphones. The listeners were randomly prompted by a call sign to respond to one of the two talkers, providing an intelligibility baseline of 0 dB signal-to-noise ratio for each test phrase. Speech maskers used were either (1) pink noise or (2) a speech babble presented over headphones or, (3) pink noise presented by loudspeakers. In general, the female talkers were the least intelligible and the male versus female pair were the most intelligible. Spatial separations of 90 deg, or more, provided up to a 25% increase in intelligibility.

Talker differences and perceptual normalization

Recognition performance for speech is generally worse for utterances produced by a mix of several talkers compared to utterances produced by a single talker. This performance impairment can be attributed to those aspects of talker normalization used to determine the vocal characteristics of the talker each time the talker changes. The present study investigated the size and nature of talker differences that may affect normalization. Spoken words were generated by a text-to-speech system for matched pairs of synthetically defined talkers. All but two of these pairs differed only in average fundamental frequency. One remaining pair of talkers differed in perceived gender but both talkers had the same average pitch; the other pair differed in both gender and pitch. Response times in a speeded word recognition task were compared for blocks of stimuli produced by a single talker and blocks of stimuli produced by a mix of one of the pairs of talkers. The results are important for understanding how listeners use pitch differences between talkers during talker normalization.

Cues to perceptual normalization of talker differences

To recognize vowels produced by a specific talker, a listener must know something about the talker's vowel space. How do listeners learn about a talkers' vowel space? How different must two talkers' vowels be to constitute different vowel spaces? To investigate these questions, listeners monitored sequences of target vowels for a specified target. In one condition, a single talker produced the vowels for each trial. In a second condition, a mix of four talkers produced the vowels for each trial. Previous research demonstrated that vowel recognition is accurate when talkers are mixed, but it requires more attention. The present study compared recognition for whispered and voiced vowels in these conditions to eliminate the use of F0 as a cue for talker normalization. Another experiment examined the effects of talker differences on normalization. Performance for a pair of talkers with similar vowel spaces was compared to performance for a pair of talkers with more disparate vowels. The results of these studi...