Working Memory and Second‐Language Accent Acquisition

We explored the proposal that overt repetition of verbal information improves the acquisition of a native accent in a second language. Mandarin-speaking Chinese learners of English were recorded while repeating and reading out English sentences before and after one of three treatments: (1) Repeating native English sentences subvocally, "covert repetition,"(2) Repeating sentences out loud, "overt repetition," and(3) Unfilled time of comparable duration. The sentences were rated by English speakers for their nativeness, fluency, and intelligibility. Overt repetition improved accent rating for read-out sentences. Covert repetition did not. Neither condition improved accent rating for repeated sentences, suggesting that immediate repetition depends on temporary rather than long-term representations. Our results provide some support for the use of overt repetition in accent learning. From a theoretical perspective, an interpretation is proposed in terms of a separation between phonological and articulatory coding within the phonological loop component of working memory

Separability of tones and rhymes in Chinese speech perception : Evidence from perceptual migrations

This study used the perceptual-migration paradigm to explore whether Mandarin tones and syllable rhymes are processed separately during Mandarin speech perception. Following the logic of illusory conjunctions, we calculated the cross-ear migration of tones, rhymes, and their combination in Chinese and English listeners. For Chinese listeners, tones migrated more than rhymes. The opposite pattern was found for English listeners. The results lend empirical support to autosegmental theory, which claims separability and mobility between tonal and segmental representations. They also provide evidence that such representations and their involvement in perception are deeply shaped by a listener’s linguistic experience

Auditory verbal working memory as a predictor of speech perception in modulated maskers in normal-hearing listeners

Purpose: Background noise can interfere with our ability to understand speech. Working memory capacity (WMC) has been shown to contribute to the perception of speech in modulated noise maskers. WMC has been assessed with a variety of auditory and visual tests, often pertaining to different components of working memory. This study assessed the relationship between speech perception in modulated maskers and components of auditory verbal working memory (AVWM) over a range of signal-to-noise ratios. Method: Speech perception in noise and AVWM were measured in 30 listeners (age range 31-67 years) with normal hearing. AVWM was estimated using forward digit recall, backward digit recall, and non-word repetition. Results: After controlling for the effects of age and average pure-tone hearing threshold, speech perception in modulated maskers was related to individual differences in the phonological component of working memory (as assessed by non-word repetition) but only in the least favorable SNR. The executive component of working memory (as assessed by backward digit) was not predictive of speech perception in any conditions. Conclusions: AVWM is predictive of the ability to benefit from temporal dips in modulated maskers: Listeners with greater phonological WMC are better able to correctly identify sentences in modulated noise backgrounds

Cognitive load elevates discrimination thresholds of duration, intensity, and f0 for a synthesized vowel

Dual-tasking negatively impacts on speech perception by raising cognitive load (CL). Previous research has shown that CL increases reliance on lexical knowledge and decreases reliance on phonetic detail. Less is known about the effect of CL on the perception of acoustic dimensions below the phonetic level. This study tested the effect of CL on the ability to discriminate differences in duration, intensity, and fundamental frequency of a synthesized vowel. A psychophysical adaptive procedure was used to obtain just noticeable differences (JNDs) on each dimension under load and no load. Load was imposed by N-back tasks at two levels of difficulty (one-back, two-back) and under two types of load (images, nonwords). Compared to a control condition with no CL, all N-back conditions increased JNDs across the three dimensions. JNDs were also higher under two-back than one-back load. Nonword load was marginally more detrimental than image load for intensity and fundamental frequency discrimination. Overall, the decreased auditory acuity demonstrates that the effect of CL on the listening experience can be traced to distortions in the perception of core auditory dimensions

Sound specificity effects in spoken word recognition : The effect of integrality between words and sounds

Recent evidence has shown that non-linguistic sounds co-occurring with spoken words may be retained in memory and affect later retrieval of the words. This "sound-specificity effect" shares many characteristics with the classic voice-specificity effect. In this study, we argue that the sound-specificity effect is conditional upon the context in which the word and sound co-exist. Specifically, we argue that, besides co-occurrence, integrality between words and sounds is a crucial factor in the emergence of the effect. In two recognition-memory experiments, we compared the emergence of voice and sound specificity effects. In Experiment 1, we examined two conditions where integrality is high. Namely, the classic voice-specificity effect (1A) was compared with a condition in which the intensity envelope of a background sound was modulated along the intensity envelope of the accompanying spoken word (1B). Results revealed a robust voice-specificity effect and, critically, a comparable sound-specificity effect: A change in the paired sound from exposure to test led to a decrease in word recognition performance. In the second experiment, we sought to disentangle the contribution of integrality from a mere co-occurrence context effect by removing the intensity modulation. The absence of integrality led to the disappearance of the sound specificity effect. Taken together, the results suggest that the assimilation of background sounds into memory cannot be reduced to a simple context effect. Rather, it is conditioned by the extent to which words and sounds are perceived as integral as opposed to distinct auditory objects

The effect of intermittent noise on lexically-guided perceptual learning in native and non-native listening

There is ample evidence that both native and non-native listeners deal with speech variation by quickly tuning into a speaker and adjusting their phonetic categories according to the speaker's ambiguous pronunciation. This process is called lexically-guided perceptual learning. Moreover, the presence of noise in the speech signal has previously been shown to change the word competition process by increasing the number of candidate words competing for recognition and slowing down the recognition process. Given that reliable lexical information should be available quickly to induce lexically-guided perceptual learning and that word recognition is slowed down in the presence of noise, and especially so for non-native listeners, the present study investigated whether noise interferes with lexically-guided perceptual learning in native and non-native listening. Native English and Dutch listeners were exposed to a story in English in clean speech or with stretches of noise. All the /l/ and /ɹ/ sounds in the story were replaced with an ambiguous sound half-way between /l/ and /ɹ/. Although noise altered the pattern of responses for the non-native listeners in a subsequent phonetic categorization task, both native and non-native listeners demonstrated lexically-guided perceptual learning in both clean and noisy listening conditions. We argue that the robustness of perceptual learning in the presence of intermittent noise for both native and non-native listeners is additional evidence for the remarkable flexibility of native and non-native perceptual systems even in adverse listening conditions.Multimedia Computin