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Purpose: This study explored clear speech (CS) and noise-adapted speech (NAS) intelligibility benefits for native and nonnative English listeners. It also examined how the two speaking style adaptations interact with maskers that vary from purely energetic to largely informational at different signal-to-noise ratios (SNRs). Method: Materials consisted of 40 sentences produced by 10 young adult talkers in a conversational and a clear speaking style under two conditions: (a) in quiet and (b) in response to speech-shaped noise (SSN) played over headphones (NAS). Young adult native (Experiment 1) and nonnative (Experiment 2) English listeners heard target sentences presented in two-talker (2T) babble, six-talker (6T) babble, or SSN and at an "easier" and a "harder" SNR. Results: When talkers produced CS and NAS, word recognition accuracy was significantly improved for both listener groups. The largest intelligibility benefit was obtained for the CS produced in response to noise (CS+NAS). Overall accuracy was highest in 2T babble. Accuracy was higher in SSN than in 6T babble for nonnative listeners at both levels of listening difficulty but only at a more difficult SNR for native listeners. Listeners benefited from CS and NAS most in the presence of SSN and least in 2T babble. When SNRs were the same for the two listener groups, native listeners outperformed nonnative listeners in almost all listening conditions, but nonnative listeners benefited more from CS and NAS in 6T babble than native listeners did. Conclusions: Combined speaking style enhancements, CS+NAS, provided the largest intelligibility increases for native and nonnative listeners in all listening conditions. The results add to the body of evidence supporting speech-oriented, behavioral therapy techniques for maximizing speech intelligibility in everyday listening situations.

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.

This study examined whether intelligibility-enhancing hyperarticulated clear speaking styles improve word segmentation during real-time speech processing in quiet and in noise. English-speaking listeners heard clearly and conversationally spoken sentences in which the target (e.g. ham) was temporarily ambiguous with a competitor (e.g. hamster) across a word boundary (e.g. ham starting) while their eye fixations to target and competitor images were recorded. Relative to conversational speech, clear speech led listeners to fixate the target image over the competitor image to a greater degree, indicating facilitation of word segmentation. Such facilitation emerged in quiet and in noise even before disambiguating segmental information (e.g. /ɑ/ in starting) was available. A parallel clear speech benefit was not found when the disyllabic word (e.g. hamster) was the target. The findings suggest that improved word segmentation partly underlies the well-documented clear speech perceptual and cognitive benefits and may arise from the enhancements of multiple word boundary cues. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated acoustic-phonetic modifications produced in noise-adapted speech (NAS) and clear speech (CS) by children, young adults, and older adults. Method: Ten children (11-13 years of age), 10 young adults (18-29 years of age), and 10 older adults (60-84 years of age) read sentences in conversational and clear speaking style in quiet and in noise. A number of acoustic measurements were obtained. Results: NAS and CS were characterized by a decrease in speaking rate and an increase in 1-3 kHz energy, sound pressure level (SPL), vowel space area (VSA), and harmonics-to-noise ratio. NAS increased fundamental frequency (F0) mean and decreased jitter and shimmer. CS increased frequency and duration of pauses. Older adults produced the slowest speaking rate, longest pauses, and smallest increase in F0 mean, 1-3 kHz energy, and SPL when speaking clearly. They produced the smallest increases in VSA in NAS and CS. Children slowed down less, increased the VSA least, increased harmonics-to-noise ratio, and decreased jitter and shimmer most in CS. Children increased mean F0 and F1 most in noise. Conclusions: Findings have implications for a model of speech production in healthy speakers as well as the potential to aid in clinical decision making for individuals with speech disorders, particularly dysarthria.

Purpose: This study examined intelligibility of conversational and clear speech sentences produced in quiet and in noise by children, young adults, and older adults. Relative talker intelligibility was assessed across speaking styles. Method: Sixty-one young adult participants listened to sentences mixed with speech-shaped noise at -5 dB signal-to-noise ratio. The analyses examined percent correct scores across conversational, clear, and noise-adapted conditions and the three talker groups. Correlation analyses examined whether talker intelligibility is consistent across speaking style adaptations. Results: Noise-adapted and clear speech significantly enhanced intelligibility for young adult listeners. The intelligibility improvement varied across the three talker groups. Notably, intelligibility benefit was smallest for children's speaking style modifications. Listeners also perceived speech produced in noise by older adults to be less intelligible compared to the younger talkers. Talker intelligibility was correlated strongly between conversational and clear speech in quiet, but not for conversational speech produced in quiet and in noise. Conclusions: Results provide evidence that intelligibility variation related to age and communicative barrier has the potential to aid clinical decision making for individuals with speech disorders, particularly dysarthria.

Purpose: The authors sought to investigate interactions among intelligibility-enhancing speech cues (i.e., semantic context, clearly produced speech, and visual information) across a range of masking conditions. Method: Sentence recognition in noise was assessed for 29 normal-hearing listeners. Testing included semantically normal and anomalous sentences, conversational and clear speaking styles, auditory-only (AO) and audiovisual (AV) presentation modalities, and 4 different maskers (2-talker babble, 4-talker babble, 8-talker babble, and speech-shaped noise). Results: Semantic context, clear speech, and visual input all improved intelligibility but also interacted with one another and with masking condition. Semantic context was beneficial across all maskers in AV conditions but only in speech-shaped noise in AO conditions. Clear speech provided the most benefit for AV speech with semantically anomalous targets. Finally, listeners were better able to take advantage of visual information for meaningful versus anomalous sentences and for clear versus conversational speech. Conclusion: Because intelligibility-enhancing cues influence each other and depend on masking condition, multiple maskers and enhancement cues should be used to accurately assess individuals' speech-in-noise perception.

Purpose: In this study, the authors examined how signal clarity interacts with the use of sentence context information in determining speech-in-noise recognition for children with cochlear implants and children with normal hearing. Method: One hundred and twenty sentences in which the final word varied in predictability (high vs. low semantic context) were produced in conversational and clear speech. Nine children with cochlear implants and 9 children with normal hearing completed the sentence-in-noise listening tests and a standardized language measure. Results: Word recognition in noise improved significantly for both groups of children for high-predictability sentences in clear speech. Children with normal hearing benefited more from each source of information compared with children with cochlear implants. There was a significant correlation between more developed language skills and the ability to use contextual enhancements. The smaller context gain in clear speech for children with cochlear implants is in accord with the effortfulness hypothesis (McCoy et al., 2005) and points to the cumulative effects of noise throughout the processing system. Conclusion: Modifications of the speech signal and the context of the utterances through changes in the talker output hold substantial promise as a communication enhancement technique for both children with cochlear implants and children with normal hearing. (Contains 2 footnotes, 5 tables, and 3 figures.)

Purpose: The objective of this project was to develop new sentence test materials drawing on a basic non-native English lexicon that could be used to test speech recognition for various listener populations. These materials have been designed to provide a test tool that is less linguistically biased, compared with materials that are currently available, for sentence recognition for non-native as well as native speakers of English. Method: One hundred non-native speakers of English were interviewed on a range of 20 conversational topics. Over 26 hr of recorded non-native English speech were transcribed. These transcriptions were used to create a lexicon of over 4,000 unique words. The words from this lexicon were used to create the new materials based on a simple syntactic sentence structure frame. Results: Twenty lists of 25 sentences were developed. Each sentence has 4 keywords, providing 100 keywords per list. Lists were equated for rate of occurrence of keywords in lexicon, high-frequency count (total number of affricates and fricatives), number of syllables, and distribution of syntactic structure. Listening-in-noise results for native-English-speaking, normal-hearing listeners indicated similar performance across lists. Conclusion: The Basic English Lexicon materials provide a large set of sentences for native and non-native English speech-recognition testing.

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 lowdepressive (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. Thirtytwo 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 signalto-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. [ABSTRACT FROM AUTHOR]