Non-native listeners' recognition of high-variability speech using PRESTO

BACKGROUND: Natural variability in speech is a significant challenge to robust successful spoken word recognition. In everyday listening environments, listeners must quickly adapt and adjust to multiple sources of variability in both the signal and listening environments. High-variability speech may be particularly difficult to understand for non-native listeners, who have less experience with the second language (L2) phonological system and less detailed knowledge of sociolinguistic variation of the L2. PURPOSE: The purpose of this study was to investigate the effects of high-variability sentences on non-native speech recognition and to explore the underlying sources of individual differences in speech recognition abilities of non-native listeners. RESEARCH DESIGN: Participants completed two sentence recognition tasks involving high-variability and low-variability sentences. They also completed a battery of behavioral tasks and self-report questionnaires designed to assess their indexical processing skills, vocabulary knowledge, and several core neurocognitive abilities. STUDY SAMPLE: Native speakers of Mandarin (n = 25) living in the United States recruited from the Indiana University community participated in the current study. A native comparison group consisted of scores obtained from native speakers of English (n = 21) in the Indiana University community taken from an earlier study. DATA COLLECTION AND ANALYSIS: Speech recognition in high-variability listening conditions was assessed with a sentence recognition task using sentences from PRESTO (Perceptually Robust English Sentence Test Open-Set) mixed in 6-talker multitalker babble. Speech recognition in low-variability listening conditions was assessed using sentences from HINT (Hearing In Noise Test) mixed in 6-talker multitalker babble. Indexical processing skills were measured using a talker discrimination task, a gender discrimination task, and a forced-choice regional dialect categorization task. Vocabulary knowledge was assessed with the WordFam word familiarity test, and executive functioning was assessed with the BRIEF-A (Behavioral Rating Inventory of Executive Function - Adult Version) self-report questionnaire. Scores from the non-native listeners on behavioral tasks and self-report questionnaires were compared with scores obtained from native listeners tested in a previous study and were examined for individual differences. RESULTS: Non-native keyword recognition scores were significantly lower on PRESTO sentences than on HINT sentences. Non-native listeners' keyword recognition scores were also lower than native listeners' scores on both sentence recognition tasks. Differences in performance on the sentence recognition tasks between non-native and native listeners were larger on PRESTO than on HINT, although group differences varied by signal-to-noise ratio. The non-native and native groups also differed in the ability to categorize talkers by region of origin and in vocabulary knowledge. Individual non-native word recognition accuracy on PRESTO sentences in multitalker babble at more favorable signal-to-noise ratios was found to be related to several BRIEF-A subscales and composite scores. However, non-native performance on PRESTO was not related to regional dialect categorization, talker and gender discrimination, or vocabulary knowledge. CONCLUSIONS: High-variability sentences in multitalker babble were particularly challenging for non-native listeners. Difficulty under high-variability testing conditions was related to lack of experience with the L2, especially L2 sociolinguistic information, compared with native listeners. Individual differences among the non-native listeners were related to weaknesses in core neurocognitive abilities affecting behavioral control in everyday life

Talker Adaptation and Lexical Difficulty Impact Word Recognition in Adults with Cochlear Implants

Introduction: Talker-specific adaptation facilitates speech recognition in normal-hearing listeners. This study examined talker adaptation in adult cochlear implant (CI) users. Three hypotheses were tested: (1) high-performing adult CI users show improved word recognition following exposure to a talker ("talker adaptation"), particularly for lexically hard words, (2) individual performance is determined by auditory sensitivity and neurocognitive skills, and (3) individual performance relates to real-world functioning. Methods: Fifteen high-performing, post-lingually deaf adult CI users completed a word recognition task consisting of 6 single-talker blocks (3 female/3 male native English speakers); words were lexically "easy" and "hard." Recognition accuracy was assessed "early" and "late" (first vs. last 10 trials); adaptation was assessed as the difference between late and early accuracy. Participants also completed measures of spectral-temporal processing and neurocognitive skills, as well as real-world measures of multiple-talker sentence recognition and quality of life (QoL). Results: CI users showed limited talker adaptation overall, but performance improved for lexically hard words. Stronger spectral-temporal processing and neurocognitive skills were weakly to moderately associated with more accurate word recognition and greater talker adaptation for hard words. Finally, word recognition accuracy for hard words was moderately related to multiple-talker sentence recognition and QoL. Conclusion: Findings demonstrate a limited talker adaptation benefit for recognition of hard words in adult CI users. Both auditory sensitivity and neurocognitive skills contribute to performance, suggesting additional benefit from adaptation for individuals with stronger skills. Finally, processing differences related to talker adaptation and lexical difficulty may be relevant to real-world functioning

The relation between speaking-style categorization and speech recognition in adult cochlear implant users

The current study examined the relation between speaking-style categorization and speech recognition in post-lingually deafened adult cochlear implant users and normal-hearing listeners tested under 4- and 8-channel acoustic noise-vocoder cochlear implant simulations. Across all listeners, better speaking-style categorization of careful read and casual conversation speech was associated with more accurate recognition of speech across those same two speaking styles. Findings suggest that some cochlear implant users and normal-hearing listeners under cochlear implant simulation may benefit from stronger encoding of indexical information in speech, enabling both better categorization and recognition of speech produced in different speaking styles.</p

Development and structure of the VariaNTS corpus:A spoken Dutch corpus containing talker and linguistic variability

Speech perception and spoken word recognition are not only affected by what is being said, but also by who is speaking. Currently, publicly available corpora of spoken Dutch do not offer a wide variety of linguistic materials produced by multiple talkers. The VariaNTS (Variatie in Nederlandse Taal en Sprekers) corpus is a Dutch spoken corpus that was developed to maximize both linguistic and talker variability. It contains 1000 items from 11 linguistic subcategories, recorded by 8 male and 8 female native speakers of standard Dutch. The corpus contains audio recordings, orthographic transcriptions, item-specific details such as word frequencies, neighborhood densities and phonotactic probabilities, and talker details. The VariaNTS corpus aims to provide new materials to be used for broad assessment of speech perception and word recognition in Dutch clinical and academic settings

Talker variability in word recognition under cochlear implant simulation:Does talker gender matter?

Normal-hearing listeners are less accurate and slower to recognize words with trial-to-trial talker changes compared to a repeating talker. Cochlear implant (CI) users demonstrate poor discrimination of same-gender talkers and, to a lesser extent, different-gender talkers, which could affect word recognition. The effects of talker voice differences on word recognition were investigated using acoustic noise-vocoder simulations of CI hearing. Word recognition accuracy was lower for multiple female and male talkers, compared to multiple female talkers or a single talker. Results suggest that talker variability has a detrimental effect on word recognition accuracy under CI simulation, but only with different-gender talkers

Noise-Vocoded Sentence Recognition and the Use of Context in Older and Younger Adult Listeners

Purpose: When listening to speech under adverse conditions, older adults, even with “age-normal” hearing, face challenges that may lead to poorer speech recognition than their younger peers. Older listeners generally demon-strate poorer suprathreshold auditory processing along with aging-related declines in neurocognitive functioning that may impair their ability to compen-sate using “top-down” cognitive–linguistic functions. This study explored top-down processing in older and younger adult listeners, specifically the use of semantic context during noise-vocoded sentence recognition. Method: Eighty-four adults with age-normal hearing (45 young normal-hearing [YNH] and 39 older normal-hearing [ONH] adults) participated. Participants were tested for recognition accuracy for two sets of noise-vocoded sentence mate-rials: one that was semantically meaningful and the other that was syntactically appropriate but semantically anomalous. Participants were also tested for hearing ability and for neurocognitive functioning to assess working memory capac-ity, speed of lexical access, inhibitory control, and nonverbal fluid reasoning, as well as vocabulary knowledge. Results: The ONH and YNH listeners made use of semantic context to a similar extent. Nonverbal reasoning predicted recognition of both meaningful and anomalous sentences, whereas pure-tone average contributed additionally to anomalous sentence recognition. None of the hearing, neurocognitive, or language measures significantly predicted the amount of context gain, computed as the difference score between meaningful and anomalous sentence recogni-tion. However, exploratory cluster analyses demonstrated four listener profiles and suggested that individuals may vary in the strategies used to recognize speech under adverse listening conditions. Conclusions: Older and younger listeners made use of sentence context to similar degrees. Nonverbal reasoning was found to be a contributor to noise-vocoded sentence recognition. However, different listeners may approach the problem of recognizing meaningful speech under adverse conditions using different strategies based on their hearing, neurocognitive, and language profiles. These findings provide support for the complexity of bottom-up and top-down interactions during speech recognition under adverse listening conditions.</p

Influence of early linguistic experience on regional dialect categorization by an adult cochlear implant user: a case study

To investigate the ability of a cochlear implant user to categorize talkers by region of origin and examine the influence of prior linguistic experience on the perception of regional dialect variation. A postlingually deafened adult cochlear implant user from the Southern region of the United States completed a six-alternative forced-choice dialect categorization task. The cochlear implant user was most accurate at categorizing unfamiliar talkers from his own region and another familiar dialect region, and least accurate at categorizing talkers from less familiar regions. Although the dialect-specific information made available by a cochlear implant may be degraded compared with information available to normal-hearing listeners, this experienced cochlear implant user was able to reliably categorize unfamiliar talkers by region of origin. The participant made use of dialect-specific acoustic-phonetic information in the speech signal and previously stored knowledge of regional dialect differences from early exposure before implantation despite an early hearing loss

Speech and Language Outcomes in Adults and Children with Cochlear Implants

Cochlear implants (CIs) represent a significant engineering and medical milestone in the treatment of hearing loss for both adults and children. In this review, we provide a brief overview of CI technology, describe the benefits that CIs can provide to adults and children who receive them, and discuss the specific limitations and issues faced by CI users. We emphasize the relevance of CIs to the linguistics community by demonstrating how CIs successfully provide access to spoken language. Furthermore, CI research can inform our basic understanding of spoken word recognition in adults and spoken language development in children. Linguistics research can also help us address the major clinical issue of outcome variability and motivate the development of new clinical tools to assess the unique challenges of adults and children with CIs, as well as novel interventions for individuals with poor outcomes

The Perception of Regional Dialects and Foreign Accents by Cochlear Implant Users

Purpose: This preliminary research examined (a) the perception of two common sources of indexical variability in speech & mdash;regional dialects and foreign accents, and (b) the relation between indexical processing and sentence recognition among prelingually deaf, long-term cochlear implant (CI) users and normal-hearing (NH) peers. Method: Forty-three prelingually deaf adolescent and adult CI users and 44 NH peers completed a regional dialect categorization task, which consisted of identifying the region of origin of an unfamiliar talker from six dialect regions of the United States. They also completed an intelligibility rating task, which consisted of rating the intelligibility of short sentences produced by native and nonnative (foreign-accented) speakers of American English on a scale from 1 (not intelligible at all) to 7 (very intelligible). Individual performance was compared to demographic factors and sentence recognition scores. Results: Both CI and NH groups demonstrated difficulty with regional dialect categorization, but NH listeners significantly outperformed the CI users. In the intelligibility rating task, both CI and NH listeners rated foreign-accented sentences as less intelligible than native sentences; however, CI users perceived smaller differences in intelligibility between native and foreign-accented sentences. Sensitivity to accent differences was related to sentence recognition accuracy in CI users. Conclusions: Prelingually deaf, long-term CI users are sensitive to accent variability in speech, but less so than NH peers. Additionally, individual differences in CI users & rsquo; sensitivity to indexical variability was related to sentence recognition abilities, suggesting a common source of difficulty in the perception and encoding of fine acoustic & ndash; phonetic details in speech