Talker Effects Research Articles

The interacting effects of talker, contrast, and listener variability in cross-language speech perception.

Building on previous observations of variability in speech research, we examine variability in speech perception study materials associated with the specific talker and contrast under examination. English-speaking listeners completed a web-based auditory AXB task involving Hindi dental-retroflex stop contrasts produced by four talkers. Main effects of talker and contrast, as well as the interaction of the two, were observed. Further, there was a great deal of individual listener variation. These findings complicate our ability to characterize the difficulty that Hindi dental-retroflex contrasts pose for English speakers, and lead to critical questions concerning the generalizability of speech perception study findings.

Intelligibility of Natively and Nonnatively Produced English Speech Presented in Noise to a Large Cohort of United States Service Members.

A corpus of English matrix sentences produced by 60 native and nonnative speakers of English was developed as part of a multinational coalition task group. This corpus was tested on a large cohort of U.S. Service members in order to examine the effects of talker nativeness, listener nativeness, masker type, and hearing sensitivity on speech recognition performance in this population. A total of 1,939 U.S. Service members (ages 18-68 years) completed this closed-set listening task, including 430 women and 110 nonnative English speakers. Stimuli were produced by native and nonnative speakers of English and were presented in speech-shaped noise and multitalker babble. Keyword recognition accuracy and response times were analyzed. General(ized) linear mixed-effects regression models found that, on the whole, speech recognition performance was lower for listeners who identified as nonnative speakers of English and when listening to speech produced by nonnative speakers of English. Talker and listener effects were more pronounced when listening in a babble masker than in a speech-shaped noise masker. Response times varied as a function of recognition score, with longest response times found for intermediate levels of performance. This study found additive effects of talker and listener nonnativeness when listening to speech in background noise. These effects were present in both accuracy and response time measures. No multiplicative effects of talker and listener language background were found. There was little evidence of a negative interaction between talker nonnativeness and hearing impairment, suggesting that these factors may have redundant effects on speech recognition. https://doi.org/10.23641/asha.26060191.

Factors influencing the minimum audible change in head orientation of a talker

Humans can detect changes in the head orientation (a.k.a. facing angle) of a talker using only auditory cues. Head orientation cues are beneficial for determining whether one is the intended recipient of an utterance and for segregating a target talker from background talkers. Because human talkers are directional sound sources, binaural cues and monoaural spectral cues can both contribute to talker head orientation perception. In this study, we assessed listeners’ sensitivity to talker head orientation changes using only monaural cues. We tested several factors that could influence the minimum audible change in head orientation: talker and gender (two male, two female), stimulus bandwidth (full-band versus low-pass filtered at 8 or 10 kHz), transducer (loudspeaker versus headphone), stimulus uncertainty (interleaved versus blocked presentation of four talkers), and vocal production mode (speech versus singing). Bandlimiting at 8 or 10 kHz led to worse performance, as did increasing stimulus uncertainty. The effect of transducer was very limited. Performance with speech was better than that with singing. The effect of talker was large and consistent, suggesting individual variability in speech directivity patterns may affect head orientation cues. [Work supported by NIH grant R01DC019745.]

Predictors of Emotional Prosody Identification by School-Age Children With Cochlear Implants and Their Peers With Normal Hearing.

Children with cochlear implants (CIs) vary widely in their ability to identify emotions in speech. The causes of this variability are unknown, but this knowledge will be crucial if we are to design improvements in technological or rehabilitative interventions that are effective for individual patients. The objective of this study was to investigate how well factors such as age at implantation, duration of device experience (hearing age), nonverbal cognition, vocabulary, and socioeconomic status predict prosody-based emotion identification in children with CIs, and how the key predictors in this population compare to children with normal hearing who are listening to either normal emotional speech or to degraded speech. We measured vocal emotion identification in 47 school-age CI recipients aged 7 to 19 years in a single-interval, 5-alternative forced-choice task. None of the participants had usable residual hearing based on parent/caregiver report. Stimuli consisted of a set of semantically emotion-neutral sentences that were recorded by 4 talkers in child-directed and adult-directed prosody corresponding to five emotions: neutral, angry, happy, sad, and scared. Twenty-one children with normal hearing were also tested in the same tasks; they listened to both original speech and to versions that had been noise-vocoded to simulate CI information processing. Group comparison confirmed the expected deficit in CI participants' emotion identification relative to participants with normal hearing. Within the CI group, increasing hearing age (correlated with developmental age) and nonverbal cognition outcomes predicted emotion recognition scores. Stimulus-related factors such as talker and emotional category also influenced performance and were involved in interactions with hearing age and cognition. Age at implantation was not predictive of emotion identification. Unlike the CI participants, neither cognitive status nor vocabulary predicted outcomes in participants with normal hearing, whether listening to original speech or CI-simulated speech. Age-related improvements in outcomes were similar in the two groups. Participants with normal hearing listening to original speech showed the greatest differences in their scores for different talkers and emotions. Participants with normal hearing listening to CI-simulated speech showed significant deficits compared with their performance with original speech materials, and their scores also showed the least effect of talker- and emotion-based variability. CI participants showed more variation in their scores with different talkers and emotions than participants with normal hearing listening to CI-simulated speech, but less so than participants with normal hearing listening to original speech. Taken together, these results confirm previous findings that pediatric CI recipients have deficits in emotion identification based on prosodic cues, but they improve with age and experience at a rate that is similar to peers with normal hearing. Unlike participants with normal hearing, nonverbal cognition played a significant role in CI listeners' emotion identification. Specifically, nonverbal cognition predicted the extent to which individual CI users could benefit from some talkers being more expressive of emotions than others, and this effect was greater in CI users who had less experience with their device (or were younger) than CI users who had more experience with their device (or were older). Thus, in young prelingually deaf children with CIs performing an emotional prosody identification task, cognitive resources may be harnessed to a greater degree than in older prelingually deaf children with CIs or than children with normal hearing.

Development of a Sentence Verification Task to Measure Speech Comprehension and Listening Effort in Cochlear Implant Users.

Tests measuring speech comprehension and listening effort for cochlear implant (CI) users may reflect important aspects of real-world speech communication. In this study, we describe the development of a multiple-talker, English-language sentence verification task (SVT) for use in adult CI users to measure speech comprehension and listening effort. We also examine whether talker differences affect speech comprehension and listening effort. Thirteen experienced adult CI users participated in the study and underwent testing using a newly developed multiple-talker SVT. Participants were sequentially presented with audio recordings of unique sentences spoken in English by six different talkers. Participants classified each sentence as either true or false. Accuracy of classification and the response time (RT) for correct responses were used as measures of comprehension and listening effort, respectively. The effect of talker on the results was further analyzed. All 13 participants successfully completed the SVT. The mean verification accuracy for participants was 87.2% ± 8.8%. The mean RT for correct responses across participants was 1,050 ms ± 391 ms. When stratified by talker, verification accuracy ranged from 83.7% to 95.2% and mean RTs across participant ranged from 786 ms to 1,254 ms. Talker did not have a significant effect on sentence classification accuracy, but it did have a significant effect on RTs (p < .001). The SVT is an easily implemented test that can assess speech comprehension and listening effort simultaneously. CI users may experience increased effort for comprehending certain talkers' speech, despite showing similar levels of comprehension accuracy. https://doi.org/10.23641/asha.24126630.

Digging into sentence intelligibility: Interactions with talker

An implicit feature found in studies of intelligibility and perception is the assumption that noise masks all spoken-sentence stimuli equivalently regardless of the stimulus-talker. For example, when using controlled and normed sentences, such as the IEEE Harvard set, the mean intelligibility across talkers should be affected by masker-noise equivalently. In other words, any particular sentence spoken by one talker should be equivalently intelligible to when it is spoken by another talker using the same style and rate. However, previous studies have shown that there is significant intelligibility variation between talkers in controlled stimuli. Therefore, we predict talker-masker interactions in the IEEE stimuli. We investigated the UAW speech intelligibility dataset which contains typed responses from over 900 native listeners of English to over 604 sentences from the UWNU IEEE sentence corpus presented in three signal-to-noise ratios ( + 2, 0, −2 dB). We calculated the Levenshtein Distance for the listeners’ transcriptions of the sentences. We find that different talkers have different intrinsic intelligibility even when reading the same set of sentences. Moreover, we find an interaction with SNR level and individual talker intelligibility. The present results suggest that individual talker effects in speech stimuli may influence the outcomes of perception and intelligibility studies.

The Influence of Male- and Female-Spoken Vowel Acoustics on Envelope-Following Responses.

The influence of male and female vowel characteristics on the envelope-following responses (EFRs) is not well understood. This study explored the role of vowel characteristics on the EFR at the fundamental frequency (f0) in response to the vowel /ε/ (as in "head"). Vowel tokens were spoken by five males and five females and EFRs were measured in 25 young adults (21 females). An auditory model was used to estimate changes in auditory processing that might account for talker effects on EFR amplitude. There were several differences between male and female vowels in relation to the EFR. For male talkers, EFR amplitudes were correlated with the bandwidth and harmonic count of the first formant, and the amplitude of the trough below the second formant. For female talkers, EFR amplitudes were correlated with the range of f0 frequencies and the amplitude of the trough above the second formant. The model suggested that the f0 EFR reflects a wide distribution of energy in speech, with primary contributions from high-frequency harmonics mediated from cochlear regions basal to the peaks of the first and second formants, not from low-frequency harmonics with energy near f0. Vowels produced by female talkers tend to produce lower-amplitude EFR, likely because they depend on higher-frequency harmonics where speech sound levels tend to be lower. This work advances auditory electrophysiology by showing how the EFR evoked by speech relates to the acoustics of speech, for both male and female voices.

Talker and accent familiarity yield advantages for voice identity perception: A voice sorting study

In the current study, we examine and compare the effects of talker and accent familiarity in the context of a voice identity sorting task, using naturally varying voice recording samples from the TV show Derry Girls. Voice samples were thus all spoken with a regional accent of UK/Irish English (from [London]derry). We tested four listener groups: Listeners were either familiar or unfamiliar with the TV show (and therefore the talker identities) and were either highly familiar or relatively less familiar with Northern Irish accents. Both talker and accent familiarity significantly improved accuracy of voice identity sorting performance. However, the talker familiarity benefits were overall larger, and more consistent. We discuss the results in light of a possible hierarchy of familiarity effects and argue that our findings may provide additional evidence for interactions of speech and identity processing pathways in voice identity perception. We also identify some key limitations in the current work and provide suggestions for future studies to address these.

The influence of lexical characteristics and talker accent on the recognition of English words by native speakers of Korean.

This study investigated the influences of lexical characteristics and talker accent on English spoken word recognition by first-language (L1) Korean second-language (L2) speakers of English. Stimuli were words that varied in phonological neighborhood density (PND) and word frequency (WF), produced by a L1 English speaker (L1 talker) and a L1 Korean speaker (L2 talker). Participants were 60 listeners from three groups: 20 L1 English speakers, 20 Korean L2 English speakers studying in the United States, and 20 Korean L2 English speakers studying in Korea. The 40 L2 English speakers varied widely in their estimated English proficiency. The results showed significant main effects of talkers, PND, and listener proficiency on word-recognition accuracy as well as significant interactions among stimulus talker (i.e., L1 vs L2 talker), PND, and WF and between stimulus talker and listener groups. However, we did not find that PND differentially affects word recognition in L2 learners, as had been found previously by Imai et al. [(2005). J. Acoust. Soc. Am. 117, 896-907] using the same design. Instead, our results paralleled closely those of Yoneyama and Munson [(2017). J. Acoust. Soc. Am. 141, 1308-1320], who examined L2 English speakers whose L1 was Japanese. These findings are discussed in light of the influence of L1 lexical structure on L2 phonological processing.

Identification of English vowels by non-native listeners: Effects of listeners’ experience of the target dialect and talkers’ language background

This study investigates how second language (L2) listeners’ perception is affected by two factors: the listeners’ experience with the target dialect – North American English (NAE) vs. Standard Southern British English (SSBE) – and talkers’ language background: native vs. non-native talkers; i.e. interlanguage speech intelligibility benefit (ISIB) talker effects. Two groups of native-Korean-speaking listeners with different target English dialects – L1-Korean listeners of English as a second language (ESL) in the USA and L1-Korean ESL listeners in the UK – were tested on the identification of 12 English vowels spoken by native and non-native (L1-Korean) talkers of NAE and SSBE. The results show that the L2 listeners’ experience with the target dialect had a significant impact on the accuracy of their identification of the L2 vowels. However, no ISIB-talker effects were observed for the L1-Korean listener groups regardless of the listeners’ differences in experience with the two varieties of English. The study adds to the L2 sound acquisition literature and the ISIB literature by looking into L2 learners’ identification of L2 vowels, taking into account the learners’ differences in experience with two standard varieties of English (NAE and SSBE) and the interaction between the learners’ experience with the two varieties and ISIB-talker effects. It also sheds some light on the issue of adult L2 learners’ ability to learn the vowels of a new target variety.

Perception of Child-Directed Versus Adult-Directed Emotional Speech in Pediatric Cochlear Implant Users.

Cochlear implants (CIs) are remarkable in allowing individuals with severe to profound hearing loss to perceive speech. Despite these gains in speech understanding, however, CI users often struggle to perceive elements such as vocal emotion and prosody, as CIs are unable to transmit the spectro-temporal detail needed to decode affective cues. This issue becomes particularly important for children with CIs, but little is known about their emotional development. In a previous study, pediatric CI users showed deficits in voice emotion recognition with child-directed stimuli featuring exaggerated prosody. However, the large intersubject variability and differential developmental trajectory known in this population incited us to question the extent to which exaggerated prosody would facilitate performance in this task. Thus, the authors revisited the question with both adult-directed and child-directed stimuli. Vocal emotion recognition was measured using both child-directed (CDS) and adult-directed (ADS) speech conditions. Pediatric CI users, aged 7-19 years old, with no cognitive or visual impairments and who communicated through oral communication with English as the primary language participated in the experiment (n = 27). Stimuli comprised 12 sentences selected from the HINT database. The sentences were spoken by male and female talkers in a CDS or ADS manner, in each of the five target emotions (happy, sad, neutral, scared, and angry). The chosen sentences were semantically emotion-neutral. Percent correct emotion recognition scores were analyzed for each participant in each condition (CDS vs. ADS). Children also completed cognitive tests of nonverbal IQ and receptive vocabulary, while parents completed questionnaires of CI and hearing history. It was predicted that the reduced prosodic variations found in the ADS condition would result in lower vocal emotion recognition scores compared with the CDS condition. Moreover, it was hypothesized that cognitive factors, perceptual sensitivity to complex pitch changes, and elements of each child's hearing history may serve as predictors of performance on vocal emotion recognition. Consistent with our hypothesis, pediatric CI users scored higher on CDS compared with ADS speech stimuli, suggesting that speaking with an exaggerated prosody-akin to "motherese"-may be a viable way to convey emotional content. Significant talker effects were also observed in that higher scores were found for the female talker for both conditions. Multiple regression analysis showed that nonverbal IQ was a significant predictor of CDS emotion recognition scores while Years using CI was a significant predictor of ADS scores. Confusion matrix analyses revealed a dependence of results on specific emotions; for the CDS condition's female talker, participants had high sensitivity (d' scores) to happy and low sensitivity to the neutral sentences while for the ADS condition, low sensitivity was found for the scared sentences. In general, participants had higher vocal emotion recognition to the CDS condition which also had more variability in pitch and intensity and thus more exaggerated prosody, in comparison to the ADS condition. Results suggest that pediatric CI users struggle with vocal emotion perception in general, particularly to adult-directed speech. The authors believe these results have broad implications for understanding how CI users perceive emotions both from an auditory communication standpoint and a socio-developmental perspective.

The Effect of Talker and Listener Depressive Symptoms on Speech Intelligibility.

Purpose This study examined the effect of depressive symptoms on production and perception of conversational and clear speech (CS) sentences. Method Five talkers each with high-depressive (HD) and low-depressive (LD) symptoms read sentences in conversational and clear speaking style. Acoustic measures of speaking rate, mean fundamental frequency (F0; Hz), F0 range (Hz), and energy in the 1-3 kHz range (dB) were obtained. Thirty-two young adult participants (15 HD, 16 LD) heard these conversational and clear sentences mixed with energetic masking (speech-shaped noise) at -5 dB SPL signal-to-noise ratio. Another group of 39 young adult participants (18 HD, 19 LD) heard the same sentences mixed with informational masking (one-talker competing speech) at -12 dB SPL signal-to-noise ratio. The key word correct score was obtained. Results CS was characterized by a decreased speaking rate, increased F0 mean and range, and increased energy in the 1-3 kHz range. Talkers with HD symptoms produced these modifications significantly less compared to talkers with LD symptoms. When listening to speech in energetic masking (speech-shaped noise), listeners with both HD and LD symptoms benefited less from the CS produced by HD talkers. Listeners with HD symptoms performed significantly worse than listeners with LD symptoms when listening to speech in informational masking (one-talker competing speech). Conclusions Results provide evidence that depressive symptoms impact intelligibility and have the potential to aid in clinical decision making for individuals with depression.

Effects of Age and Hearing Loss on the Recognition of Emotions in Speech.

Emotional communication is a cornerstone of social cognition and informs human interaction. Previous studies have shown deficits in facial and vocal emotion recognition in older adults, particularly for negative emotions. However, few studies have examined combined effects of aging and hearing loss on vocal emotion recognition by adults. The objective of this study was to compare vocal emotion recognition in adults with hearing loss relative to age-matched peers with normal hearing. We hypothesized that age would play a role in emotion recognition and that listeners with hearing loss would show deficits across the age range. Thirty-two adults (22 to 74 years of age) with mild to severe, symmetrical sensorineural hearing loss, amplified with bilateral hearing aids and 30 adults (21 to 75 years of age) with normal hearing, participated in the study. Stimuli consisted of sentences spoken by 2 talkers, 1 male, 1 female, in 5 emotions (angry, happy, neutral, sad, and scared) in an adult-directed manner. The task involved a single-interval, five-alternative forced-choice paradigm, in which the participants listened to individual sentences and indicated which of the five emotions was targeted in each sentence. Reaction time was recorded as an indirect measure of cognitive load. Results showed significant effects of age. Older listeners had reduced accuracy, increased reaction times, and reduced d' values. Normal hearing listeners showed an Age by Talker interaction where older listeners had more difficulty identifying male vocal emotion. Listeners with hearing loss showed reduced accuracy, increased reaction times, and lower d' values compared with age-matched normal-hearing listeners. Within the group with hearing loss, age and talker effects were significant, and low-frequency pure-tone averages showed a marginally significant effect. Contrary to other studies, once hearing thresholds were taken into account, no effects of listener sex were observed, nor were there effects of individual emotions on accuracy. However, reaction times and d' values showed significant differences between individual emotions. The results of this study confirm existing findings in the literature showing that older adults show significant deficits in voice emotion recognition compared with their normally hearing peers, and that among listeners with normal hearing, age-related changes in hearing do not predict this age-related deficit. The present results also add to the literature by showing that hearing impairment contributes additionally to deficits in vocal emotion recognition, separate from deficits related to age. These effects of age and hearing loss appear to be quite robust, being evident in reduced accuracy scores and d' measures, as well as in reaction time measures.

The effects of parental interaction on French-English bilingual infants’ vocalization and turn-taking rates

Prior studies suggest that parent-infant interactions play an important role on infant volubility, which is an important indication of language development. However, little is known about how speaker and language contexts affect infant volubility in bilingual infants. In the current study, we examined how the speaker context (Mother versus Father) and the language context (French versus English) might influence bilingual infants’ rate of vocalization and turn-taking. We analyzed naturalistic daylong recordings from English-French bilingual parent/infant dyads (n = 21). Preliminary analysis showed that mothers elicited more turn-taking in their 10-month-old infants than fathers did, but they did not elicit more vocalizations. Importantly, there was no effect of language on infant vocalization or turn-taking. We will alsoreport analyses that examine whether the dominant language in the bilingual child’s input has an effect on infant volubility that is independent of talker effects. These novel findings will inform our understanding of how parent-infant interactions shape the language development of infants being raised in bilingual families.

Are there sex effects for speech intelligibility in American English? Examining the influence of talker, listener, and methodology.

Talker and listener sex in speech processing has been largely unknown and under-appreciated to this point, with many studies overlooking the possible influences. In the current study, the effects of both talker and listener sex on speech intelligibility were assessed. Different methodological approaches to measuring intelligibility (percent words correct vs. subjective rating scales) and collecting data (laboratory vs. crowdsourcing) were also evaluated. Findings revealed that, regardless of methodology, the spoken productions of female talkers were overall more intelligible than the spoken productions of male talkers; however, substantial variability across talkers was observed. Findings also revealed that when data were collected in the lab, there was an interaction between talker and listener sex. This interaction between listener and talker sex was not observed when subjective ratings were crowdsourced from listener subjects across the USA via Amazon Mechanical Turk, although overall ratings remained similar. This possibly suggests that subjective intelligibility ratings may be vulnerable to bias, and such biases may be reduced by recruiting a more heterogeneous subject pool. Many studies in speech perception do not account for these talker, listener, and methodology effects. However, the present results suggest that researchers should carefully consider these effects when assessing speech intelligibility in different conditions, and when comparing findings across studies that have used different subject demographics and/or methodologies.

Acoustic cues for vocal emotion recognition by normal-hearing listeners and cochlear implant users

Our recent study found that cochlear implant (CI) users’ quality of life in auditory, psychological, and social functioning were predicted by vocal emotion rather than sentence recognition scores. To eventually improve vocal emotion recognition with CIs, this study investigated the acoustic cues for vocal emotion recognition by CI users with CI alone or bimodal fitting, as compared to normal-hearing (NH) listeners. Sentence duration, mean fundamental frequency (F0), and F0 range were individually normalized for emotional utterances of each talker and sentence. In two other conditions, emotional utterances were presented backward in time and with upside-down F0 contours, respectively. Perceptual results showed significant effects of subject group, cue condition, talker, and emotion. Time-reversed utterances worsened NH listeners’ recognition of all emotions except sad, while upside-down F0 contours worsened that of angry and happy. Vocal emotion recognition with CI alone only degraded with time-reversed utterances. Time-reversed utterances worsened bimodal CI users’ recognition of angry and neutral, while upside-down F0 contours worsened that of angry and happy. Bimodal CI users and NH listeners were also affected by mean F0 and F0 range normalization when recognizing happy. We conclude that natural F0 contours should be faithfully encoded with CIs for better vocal emotion recognition.

Speech-material and talker effects in speech band importance.

Band-importance functions created using the compound method [Apoux and Healy (2012). J. Acoust. Soc. Am. 132, 1078-1087] provide more detail than those generated using the ANSI technique, necessitating and allowing a re-examination of the influences of speech material and talker on the shape of the band-importance function. More specifically, the detailed functions may reflect, to a larger extent, acoustic idiosyncrasies of the individual talker's voice. Twenty-one band functions were created using standard speech materials and recordings by different talkers. The band-importance functions representing the same speech-material type produced by different talkers were found to be more similar to one another than functions representing the same talker producing different speech-material types. Thus, the primary finding was the relative strength of a speech-material effect and weakness of a talker effect. This speech-material effect extended to other materials in the same broad class (different sentence corpora) despite considerable differences in the specific materials. Characteristics of individual talkers' voices were not readily apparent in the functions, and the talker effect was restricted to more global aspects of talker (i.e., gender). Finally, the use of multiple talkers diminished any residual effect of the talker.

Perceptual similarity judgments of voices: Effects of talker and listener language, vocal source acoustics, and time-reversal

Listeners demonstrate reliable perceptual biases favoring voices speaking their native language versus those speaking a foreign language. This “language-familiarity effect” for voice processing has been found even for perceptual similarity judgments: Voices speaking listeners’ native language sound less alike, even when those recordings have been rendered incomprehensible via time-reversal. Here, we sought to replicate and extend this finding of linguistic effects on voice similarity. Native English- and Mandarin-speaking listeners (both N = 40) rated the perceptual similarity of voices speaking English or Mandarin (both N = 20) for either time-reversed or forward speech. Both listener groups tended to find Mandarin-speaking voices more dissimilar, but this effect was reduced for English-speaking listeners, especially for forward speech. Perceptual similarity judgments of voices were always highly correlated between listener groups and between forward/time-reversed speech. Acoustic measurements (voice fundamental frequency mean and variance, local jitter, harmonics-to-noise ratio, speech rate, and formant dispersion) were also made to ascertain how listeners’ perceptual similarity judgments were related to speech acoustics and whether these relationships differed under time-reversal or across listeners’ or talkers’ native language. Overall, these data suggest that, while native language may influence perceptual dissimilarity of voices, the magnitude of these effects tend to be very small.

Hearing taboo words can result in early talker effects in word recognition for female listeners.

Previous spoken word recognition research using the long-term repetition-priming paradigm found performance costs for stimuli mismatching in talker identity. That is, when words were repeated across the two blocks, and the identity of the talker changed reaction times (RTs) were slower than when the repeated words were spoken by the same talker. Such performance costs, or talker effects, followed a time course, occurring only when processing was relatively slow. More recent research suggests that increased explicit and implicit attention towards the talkers can result in talker effects even during relatively fast processing. The purpose of the current study was to examine whether word meaning would influence the pattern of talker effects in an easy lexical decision task and, if so, whether results would differ depending on whether the presentation of neutral and taboo words was mixed or blocked. Regardless of presentation, participants responded to taboo words faster than neutral words. Furthermore, talker effects for the female talker emerged when participants heard both taboo and neutral words (consistent with an attention-based hypothesis), but not for participants that heard only taboo or only neutral words (consistent with the time-course hypothesis). These findings have important implications for theoretical models of spoken word recognition.

Communication in military environments: Influence of noise, hearing protection and language proficiency

Military training and international operations require different nationalities to communicate in a common language, where there are potential challenges with non-native (L2) speech communication. An experiment of speech communication in military noise was conducted for co-located (face-to-face [F2F]) and distributed (using communication headsets) talker-listener pairs. Half of the twenty-four participants were monolingual English speakers (native group, NA) and the remaining half had obtained English fluency after the age of eight years (non-native group, NN). Two tests of speech understanding were used: the Modified Rhyme Test (MRT) and the Speech Perception in Noise test (SPIN). In the F2F condition, the participants wore a communication headset (earmuff) with the power off for occluded listening. Three levels of armoured vehicle noise were used, 55, 60 and 65dBA, for speech-to-noise ratios ranging from −10 to +5dB. In the radio condition, the pairs were separated by a visual barrier and used the communication headset for the tests in 80dBA armoured vehicle noise. The results showed that the NN group had difficulty with the SPIN test in the radio and F2F conditions. This result was attributed to the open-response set of the SPIN. Headset occlusion likely contributed to the lower scores for the NN listeners in the F2F condition. There was a main effect of talker for the MRT in the F2F and radio conditions, and for the SPIN in the radio condition, suggesting that foreign accent reduced the intelligibility for both the NA and NN groups. The results were surprising considering the high L2 proficiency of the NN group. Training methods for improving L2 communication in operational settings should be further investigated.