The time-course of linguistic interference during native and non-native speech-in-speech listening.

Recognizing speech in a noisy background is harder when the background is time-forward than for time-reversed speech, a masker direction effect, and harder when the masker is in a known rather than an unknown language, indicating linguistic interference. We examined the masker direction effect when the masker was a known vs unknown language and calculated performance over 50 trials to assess differential masker adaptation. In experiment 1, native English listeners transcribing English sentences showed a larger masker direction effect with English than Mandarin maskers.

Phonetic categorization and discrimination of voice onset time under divided attention.

Event durations are perceived to be shorter under divided attention. "Time shrinkage" is thought to be due to rapid attentional switches between tasks, leading to a loss of input samples, and hence, an under-estimation of duration. However, few studies have considered whether this phenomenon applies to durations relevant to time-based phonetic categorization.

Effects of Cognitive Load on Pure-Tone Audiometry Thresholds in Younger and Older Adults.

Objectives: Cognitive load (CL) impairs listeners' ability to comprehend sentences, recognize words, and identify speech sounds. Recent findings suggest that this effect originates in a disruption of low-level perception of acoustic details. Here, we attempted to quantify such a disruption by measuring the effect of CL (a two-back task) on pure-tone audiometry (PTA) thresholds.

Cognitive load elevates discrimination thresholds of duration, intensity, and f 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.

Statistical learning for speech segmentation: Age-related changes and underlying mechanisms.

Statistical learning (SL) is a powerful learning mechanism that supports word segmentation and language acquisition in infants and young adults. However, little is known about how this ability changes over the life span and interacts with age-related cognitive decline. The aims of this study were to: (a) examine the effect of aging on speech segmentation by SL, and (b) explore core mechanisms underlying SL.

Lexical knowledge boosts statistically-driven speech segmentation.

The hypothesis that known words can serve as anchors for discovering new words in connected speech has computational and empirical support. However, evidence for how the bootstrapping effect of known words interacts with other mechanisms of lexical acquisition, such as statistical learning, is incomplete. In 3 experiments, we investigated the consequences of introducing a known word in an artificial language with no segmentation cues other than cross-syllable transitional probabilities.

Anterior paracingulate and cingulate cortex mediates the effects of cognitive load on speech sound discrimination.

Perceiving speech while performing another task is a common challenge in everyday life. How the brain controls resource allocation during speech perception remains poorly understood. Using functional magnetic resonance imaging (fMRI), we investigated the effect of cognitive load on speech perception by examining brain responses of participants performing a phoneme discrimination task and a visual working memory task simultaneously.

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.

Is the superior verbal memory span of Mandarin speakers due to faster rehearsal?

It is well established that digit span in native Chinese speakers is atypically high. This is commonly attributed to a capacity for more rapid subvocal rehearsal for that group. We explored this hypothesis by testing a group of English-speaking native Mandarin speakers on digit span and word span in both Mandarin and English, together with a measure of speed of articulation for each.

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

Recent evidence has shown that nonlinguistic 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 coexist.

Magnified Neural Envelope Coding Predicts Deficits in Speech Perception in Noise.

Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds.

Auditory Verbal Working Memory as a Predictor of Speech Perception in Modulated Maskers in Listeners With Normal Hearing.

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.

How does cognitive load influence speech perception? An encoding hypothesis.

Two experiments investigated the conditions under which cognitive load exerts an effect on the acuity of speech perception. These experiments extend earlier research by using a different speech perception task (four-interval oddity task) and by implementing cognitive load through a task often thought to be modular, namely, face processing. In the cognitive-load conditions, participants were required to remember two faces presented before the speech stimuli.

Speech segmentation by statistical learning is supported by domain-general processes within working memory.

The purpose of this study was to examine the extent to which working memory resources are recruited during statistical learning (SL). Participants were asked to identify novel words in an artificial speech stream where the transitional probabilities between syllables provided the only segmentation cue. Experiments 1 and 2 demonstrated that segmentation performance improved when the speech rate was slowed down, suggesting that SL is supported by some form of active processing or maintenance mechanism that operates more effectively under slower presentation rates.

Beating the bounds: Localized timing cues to word segmentation.

Prosody facilitates perceptual segmentation of the speech stream into a sequence of words and phrases. With regard to speech timing, vowel lengthening is well established as a cue to an upcoming boundary, but listeners' exploitation of consonant lengthening for segmentation has not been systematically tested in the absence of other boundary cues. In a series of artificial language learning experiments, the impact of durational variation in consonants and vowels on listeners' extraction of novel trisyllables was examined.

Divided attention disrupts perceptual encoding during speech recognition.

Performing a secondary task while listening to speech has a detrimental effect on speech processing, but the locus of the disruption within the speech system is poorly understood. Recent research has shown that cognitive load imposed by a concurrent visual task increases dependency on lexical knowledge during speech processing, but it does not affect lexical activation per se. This suggests that "lexical drift" under cognitive load occurs either as a post-lexical bias at the decisional level or as a secondary consequence of reduced perceptual sensitivity.

Phoneme categorization and discrimination in younger and older adults: a comparative analysis of perceptual, lexical, and attentional factors.

This study investigates the extent to which age-related language processing difficulties are due to a decline in sensory processes or to a deterioration of cognitive factors, specifically, attentional control. Two facets of attentional control were examined: inhibition of irrelevant information and divided attention. Younger and older adults were asked to categorize the initial phoneme of spoken syllables ("Was it m or n?"), trying to ignore the lexical status of the syllables.

Extrinsic cognitive load impairs low-level speech perception.

Recent research has suggested that the extrinsic cognitive load generated by performing a nonlinguistic visual task while perceiving speech increases listeners' reliance on lexical knowledge and decreases their capacity to perceive phonetic detail. In the present study, we asked whether this effect is accounted for better at a lexical or a sublexical level. The former would imply that cognitive load directly affects lexical activation but not perceptual sensitivity; the latter would imply that increased lexical reliance under cognitive load is only a secondary consequence of imprecise or incomplete phonetic encoding.

Segmentation cues in conversational speech: robust semantics and fragile phonotactics.

Multiple cues influence listeners' segmentation of connected speech into words, but most previous studies have used stimuli elicited in careful readings rather than natural conversation. Discerning word boundaries in conversational speech may differ from the laboratory setting. In particular, a speaker's articulatory effort - hyperarticulation vs.

How stable are acoustic metrics of contrastive speech rhythm?

Acoustic metrics of contrastive speech rhythm, based on vocalic and intervocalic interval durations, are intended to capture stable typological differences between languages. They should consequently be robust to variation between speakers, sentence materials, and measurers. This paper assesses the impact of these sources of variation on the metrics %V (proportion of utterance comprised of vocalic intervals), VarcoV (rate-normalized standard deviation of vocalic interval duration), and nPVI-V (a measure of the durational variability between successive pairs of vocalic intervals).

The activation of embedded words in spoken word identification is robust but constrained: evidence from the picture-word interference paradigm.

Three picture-word interference (PWI) experiments assessed the extent to which embedded subset words are activated during the identification of spoken superset words (e.g., bone in trombone).

Quantifying speech rhythm abnormalities in the dysarthrias.

Purpose: In this study, the authors examined whether rhythm metrics capable of distinguishing languages with high and low temporal stress contrast also can distinguish among control and dysarthric speakers of American English with perceptually distinct rhythm patterns. Methods Acoustic measures of vocalic and consonantal segment durations were obtained for speech samples from 55 speakers across 5 groups (hypokinetic, hyperkinetic, flaccid-spastic, ataxic dysarthrias, and controls). Segment durations were used to calculate standard and new rhythm metrics.

Preserved implicit knowledge of a forgotten childhood language.

Previous research suggests that a language learned during early childhood is completely forgotten when contact to that language is severed. In contrast with these findings, we report leftover traces of early language exposure in individuals in their adult years, despite a complete absence of explicit memory for the language. Specifically, native English individuals under age 40 selectively relearned subtle Hindi or Zulu sound contrasts that they once knew.

Optical phonetics and visual perception of lexical and phrasal stress in English.

In a study of optical cues to the visual perception of stress, three American English talkers spoke words that differed in lexical stress and sentences that differed in phrasal stress, while video and movements of the face were recorded. The production of stressed and unstressed syllables from these utterances was analyzed along many measures of facial movement, which were generally larger and faster in the stressed condition. In a visual perception experiment, 16 perceivers identified the location of stress in forced-choice judgments of video clips of these utterances (without audio).

Segmentation by lexical subtraction in Hungarian speakers of second-language English.

Using cross-modal form priming, we compared the use of stress and lexicality in the segmentation of spoken English by native English speakers (L1) and by native Hungarian speakers of second-language English (L2). For both language groups, lexicality was found to be an effective segmentation cue. That is, spoken disyllabic word fragments were stronger primes in a subsequent visual word recognition task when preceded by meaningful words than when preceded by nonwords: For example, the first two syllables of corridor were a more effective prime for visually presented corridor when heard in the phrase anythingcorri than in imoshingcorri.