The impact of visual cues and lexical knowledge on the perception of a non-native consonant contrast for Colombian adults

The study investigates the impact of visual cues and lexical knowledge on the identification of a nonnative phonemic contrast. Twenty native Colombians were tested on an identification task involving 16 minimal pairs of English words, produced by four English speakers, contrasting in the presence of /b/ or /v/ in initial or medial position. The test was run in three conditions: audiovisual (AV), audio only (A) or visual only (V). Prior to the identification task, their knowledge of the lexical items was evaluated; they were also recorded while reading the words. Mean identification scores were higher for the AV than the A condition, but V and AV scores not differ. Relative to previous /b/-/v/ studies with Peninsular Spanish speakers, Colombians relied more heavily on visual cues in their identification of /b/-/v/. Although there was a trend for identification scores to be higher for known lexical items, this effect was not statistically significant. Finally, production accuracy for the /b/-/v/ contrast was not correlated with perception accuracy, but production tended to be more accurate in speakers with better lexical knowledge. The visual weighting results suggest that the degree of visual bias in speech perception may be ‘culture-specific’ rather than merely ‘language-specific’

Individual variability in the perceptual learning of L2 speech sounds and its cognitive correlates

This study explored which cognitive processes are related to individual variability in the learning of novel phonemic contrasts in a second language. 25 English participants were trained to perceive a Korean stop voicing contrast which is novel for English speakers. They were also presented with a large battery of tests which investigated different aspects of their perceptual and cognitive abilities, as well as pre- and posttraining tests of their ability to discriminate this novel consonant contrast. The battery included: adaptive psychoacoustic tasks to determine frequency limens, a paired-association task looking at the ability to memorise the pairing of two items, a backward digit span task measuring working memory span, a sentence perception in noise task that quantifies the effect of top-down information as well as signal detection ability, a sorting task investigating the attentional filtering of the key acoustic features. The general measures that were the most often correlated with the ability to learn the novel phonetic contrast were measures of attentional switching (i.e. the ability to reallocate attention), the ability to sort stimuli according to a particular dimension, which is also somewhat linked to allocation of attention, frequency acuity and the ability to associate two unrelated events

Is Consonant Perception Linked to Within-Category Dispersion or Across-Category Distance?

This study investigated the relation between the internal structure of phonetic categories and consonant intelligibility. For two phonetic contrasts (/s/-/S/ and /b/-/p/), 32 iterations per category were elicited for each of 40 talkers from a same accent group and age range, and measures of cross-category distance and within-category dispersion were obtained. These measures varied substantially across talkers but were not correlated across both contrasts suggesting that degree of cross-category distance or within-category dispersion is not consistent within-speaker. For each contrast, consonant identification tests in mild babble noise, that presented the complete set of iterations for eight talkers showing extreme values in these two measures, revealed some talker effects on reaction time. However, these did not appear to be correlated with either cross-category distance or within-category dispersion for those talkers

The development of clear speech strategies in 9-14 year olds

This study investigated the development of global clear speech strategies of child talkers. Two groups of 20 talkers aged 9-10 (children) and 13-14 (teens) were recorded in pairs while they carried out spot the difference picture tasks, either hearing each other normally (NB condition) or with one talker hearing the other via a three-channel noise vocoder (VOC condition). Acoustic-phonetic analyses focused on the talker having to overcome the communication barrier. Data were compared to those for 20 of the adults in Hazan and Baker (2011) [J.Acoust.Soc, Am, 130, 2139-2152]. The three age groups did not differ in task transaction time for NB, but children took significantly longer to complete the task in VOC than teens or adults who took equally long. Children spoke at a slower speech rate overall than teens, while teens and adults did not differ; all groups significantly reduced their speech rate in VOC relative to NB. Adults hyperarticulated vowels in VOC but children and teens showed only minor adaptations. These results suggest that although 9-10 year olds use some strategies to clarify their speech in difficult conditions, other strategies continue to develop into late adolescence

Speech perception abilities of adults with dyslexia: is there any evidence for a true deficit?

PURPOSE: This study investigated whether adults with dyslexia show evidence of a consistent speech perception deficit by testing phoneme categorization and word perception in noise. METHOD: Seventeen adults with dyslexia and 20 average readers underwent a test battery including standardized reading, language and phonological awareness tests, and tests of speech perception. Categorization of a pea/bee voicing contrast was evaluated using adaptive identification and discrimination tasks, presented in quiet and in noise, and a fixed-step discrimination task. Two further tests of word perception in noise were presented. RESULTS: There were no significant group differences for categorization in quiet or noise, across- and within-category discrimination as measured adaptively, or word perception, but average readers showed better across- and within-category discrimination in the fixed-step discrimination task. Individuals did not show consistent poor performance across related tasks. CONCLUSIONS: The small number of group differences, and lack of consistent poor individual performance, suggests weak support for a speech perception deficit in dyslexia. It seems likely that at least some poor performances are attributable to nonsensory factors like attention. It may also be that some individuals with dyslexia have speech perceptual acuity that is at the lower end of the normal range and exacerbated by nonsensory factors

Acoustic-Phonetic Characteristics of Clear Speech in Bilinguals

This study examined the language-dependency of clear speech modifications by comparing the clear speech strategies of late bilinguals in both their L1 (Finnish) and L2 (English). Results generally supported the hypothesis of language-independent enhancement of global clear speech modifications, but language-dependent segmental enhancement. The global clear speech strategies produced by Finnish-English bilinguals in their L2 (English) were similar in the extent of the modifications to those of native English speakers, indicating a surprising flexibility of the non-native speech production system

Do talkers produce less dispersed phoneme categories in a clear speaking style?

This study investigated whether adaptations made in clear speaking styles result in more discriminable phonetic categories than in a casual style. Multiple iterations of keywords with word-initial /s/-/ʃ/ were obtained from 40 adults in casual and clear speech via picture description. For centroids, cross-category distance increased in clear 8 speech but with no change in within-category dispersion and no effect on discriminability. However, talkers produced fewer tokens with centroids in the ambiguous region for the /s/-/ʃ/ distinction. These results suggest that, whereas interlocutor feedback regarding communicative success may promote greater segmental adaptations, it is not necessary for some adaptation to occur

Clear Speech strategies and speech perception in adverse listening conditions

The study investigated the impact of different types of clear speech on speech perception in an adverse listening condition. Tokens were extracted from spontaneous speech dialogues in which participants completed a problem-solving task in good listening conditions or while experiencing a one-sided ‘communication barrier’: a real-time vocoder or multibabble noise. These two adverse conditions induced the ‘unimpaired’ participant to produce clear speech. When tokens from these three conditions were presented in multibabble noise, listeners were quicker at processing clear tokens produced to counter the effects of multibabble noise than clear tokens produced to counteract the vocoder, or tokens produced in good communicative conditions. A clarity rating experiment using the same tokens presented in quiet showed that listeners do not distinguish between different types of clear speech. Together, these results suggest that clear speaking styles produced in different communicative conditions have acoustic-phonetic characteristics adapted to the needs of the listener, even though they may be perceived as being of similar clarity

Cadaveric simulation for improving surgical training in dermatology.

Simulation models are rapidly changing medical education, especially the training of dermatology residents. Various models are available, including cadaveric simulations. Our study evaluates the impact of a cadaveric simulation on the training of dermatology residents. Over a period of three years, cadaveric simulation was shown to increase the surgical knowledge of residents. Residents were more confident in their knowledge of surgical anatomy and also surgical skills. Cadaveric simulation may offer a positive impact on resident training in dermatology

Speech modifications in interactive speech: Effects of age, sex and noise type

When attempting to maintain conversations in noisy communicative settings, talkers typically modify their speech to make themselves understood by the listener. In this study, we investigated the impact of background interference type and talker age on speech adaptations, vocal effort and communicative success. We measured speech acoustics (articulation rate, mid-frequency energy, fundamental frequency), vocal effort (correlation between mid-frequency energy and fundamental frequency) and task completion time in 114 participants aged 8–80 years carrying out an interactive problem-solving task in good and noisy listening conditions (quiet, non-speech noise, background speech). We found greater changes in fundamental frequency and mid-frequency energy in non-speech noise than in background speech and similar reductions in articulation rate in both. However, older participants (50+ years) increased vocal effort in both background interference types, whereas younger children (less than 13 years) increased vocal effort only in background speech. The presence of background interference did not lead to longer task completion times. These results suggest that when the background interference involves a higher cognitive load, as in the case of other speech of other talkers, children and older talkers need to exert more vocal effort to ensure successful communication. We discuss these findings within the communication effort framework. This article is part of the theme issue ‘Voice modulation: from origin and mechanism to social impact (Part II)’