Best practices for communication while wearing facemasks: A scoping review.

INTRODUCTION: Facemasks are an important piece of personal protective equipment (PPE) to mitigate the spread of respiratory illnesses, but they can impede communication between patients and healthcare providers. The purpose of this scoping review is to identify effective communication practices while wearing facemasks. DESIGN: Scoping review using a systematic search of articles from the PubMed, CINAHL, and Embase databases. METHODS: The PEO (population, exposure, outcome) methodology was selected for this systematic scoping review. The population of interest (P) includes humans of all ages (children, adults, and older adults); the exposure of interest (E) is PPE that covers the mouth (i.e., facemasks); and the outcome of interest (O) is successful or unsuccessful communication practices. The Johns Hopkins Evidence-Based Practice for Nurses and Healthcare Professionals appraisal guidelines were used to determine the level and quality of the research. RESULTS: Thirty-nine articles met the inclusion criteria. Seventeen of these were high- or good-quality research studies, and the remaining 22 were non-research articles included with separate analysis as part of the scoping review. The 17 articles encompassed 2656 participants. The highest quality evidence indicated that standard surgical masks have the least impact on speech perception compared to other non-transparent mask types, and that recognizing emotions is less accurate with facemasks, necessitating compensatory actions (i.e., reducing extraneous noise, using a microphone to amplify voice, and employing clear speech). Evidence was contradictory regarding the use of transparent masks. Evidence was of limited quality for other non-verbal and verbal communication strategies. CONCLUSION: Awareness of communication challenges is crucial when wearing facemasks. More high-quality studies are needed to evaluate communication techniques when speakers are wearing facemasks. Basic strategies such as selecting an appropriate mask type, reducing extraneous noise, using microphones, verbalizing emotions, and employing clear speech appear to be beneficial. CLINICAL RELEVANCE: The findings of this scoping review highlight the importance of considering communication challenges while wearing facemasks in the healthcare settings. The review suggests that selecting an appropriate mask type, reducing extraneous noise, verbalizing emotions, and employing clear speech are some strategies that may be effective in mitigating the impact of facemasks on communication between patients and healthcare providers.

The Effect of Clear Speech on Cantonese Alaryngeal Speakers' Intelligibility.

BACKGROUND/AIM: The purpose of this study was to provide preliminary data concerning the effect of clear speech (CS) on Cantonese alaryngeal speakers' intelligibility. METHODS: Voice recordings of 11 sentences randomly selected from the Cantonese Sentence Intelligibility Test (CSIT) were obtained from 31 alaryngeal speakers (9 electrolarynx [EL] users, 10 esophageal speakers and 12 tracheoesophageal [TE] speakers) in habitual speech (HS) and CS. Two naïve listeners orthographically transcribed a total of 1,364 sentences. RESULTS: Significant effects of speaking condition on speaking rate and CSIT scores were observed, but no significant effect of alaryngeal communication methods was noted. CS was significantly slower than HS by 0.78 syllables/s. Esophageal speakers demonstrated the slowest speech rate when using CS, while EL users demonstrated the largest decrease in speaking rate when using CS compared to HS. TE speakers had the highest CSIT scores in HS (listener 1 = 81.4%; listener 2 = 81.3%), and esophageal speakers had the highest CSIT scores in CS (listener 1 = 87.5%; listener 2 = 89.7%). EL users experienced the largest increase in intelligibility while using CS compared to HS (9.1%) followed by esophageal speakers (8.9%) and TE speakers (1.4%). CONCLUSION: Preliminary data indicate that CS may significantly affect Cantonese alaryngeal speakers' speaking rate and intelligibility. However, intelligibility appeared to vary considerably across speakers. Further research involving larger, heterogeneous groups of speakers and listeners alongside longer and more refined CS training protocols should be conducted to confirm that CS can improve Cantonese alaryngeal speakers' intelligibility.

Electrocorticography reveals continuous auditory and visual speech tracking in temporal and occipital cortex.

During natural speech perception, humans must parse temporally continuous auditory and visual speech signals into sequences of words. However, most studies of speech perception present only single words or syllables. We used electrocorticography (subdural electrodes implanted on the brains of epileptic patients) to investigate the neural mechanisms for processing continuous audiovisual speech signals consisting of individual sentences. Using partial correlation analysis, we found that posterior superior temporal gyrus (pSTG) and medial occipital cortex tracked both the auditory and the visual speech envelopes. These same regions, as well as inferior temporal cortex, responded more strongly to a dynamic video of a talking face compared to auditory speech paired with a static face. Occipital cortex and pSTG carry temporal information about both auditory and visual speech dynamics. Visual speech tracking in pSTG may be a mechanism for enhancing perception of degraded auditory speech.

Dysarthria enhancement mechanism under external clear speech instruction in Parkinson's disease, progressive supranuclear palsy and multiple system atrophy.

Clear speech refers to intentionally modifying conversational speech to maximise intelligibility. This study aimed to compare the speech behaviour of patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and Parkinson's disease (PD) under conversational and clear speech conditions to gain greater pathophysiological insight. A total of 68 participants including 17 PD, 17 MSA, 17 PSP and 17 healthy controls (HC) performed two readings of the same standardized passage. During the first reading, participants were instructed to read the text in an ordinary way, while during the second reading to read the text as clearly as possible. Acoustic analyses were based upon measurements of mean loudness, loudness variability, pitch variability, vowel articulation, articulation rate and speech severity. During clear speech production, PD patients were able to achieve improvements mainly in loudness (p < 0.05) and pitch variability (p < 0.001), leading to a reduction in overall speech severity (p < 0.001), whereas PSP and MSA patients were able to modulate only articulation rate (p < 0.05). Contrary to HC and PD groups, which slowed or maintained articulation rate, PSP and MSA groups employed a markedly faster articulation rate under the clear speech condition indicating an opposing approach to speech adaptation. Patients with atypical Parkinsonism showed a different strategy to intentionally improve their speech performance following a simple request to produce speech more clearly compared to PD, suggesting important therapeutic implications for speech rehabilitation management.

Clear versus casual consonant identification by hearing-impaired and normal-hearing listeners.

Hearing-impaired (HI) listeners who benefit from hearing-aid use in quiet often continue to have difficulty understanding speech in noise. Requesting talkers to speak clearly is one strategy to overcome this deficit. Paradoxically, one feature of clear speech is a shift to higher frequencies, which may move speech energy into a frequency range that is inaudible or more distorted for some HI listeners. Casual (or conversational) speech, on the other hand, may shift speech energy into a lower frequency range that is more audible or less distorted. This study examined the intelligibility of 21 amplified, casually- and clearly-spoken, US English coda consonants in nonsense syllables for 10 normal-hearing (NH) and 17 HI listeners. Most clear-speech consonants yielded higher recognition scores as expected. However, certain phonological processes common in casual speech, such as palatalization of higher frequency alveolar into lower frequency postalveolar consonants, generated significantly higher scores than their clear counterparts for some HI listeners in noise. These results have implications for coaching conversational partners of aided HI listeners. For the military, talkers can be instructed how to speak to Service members with hearing loss or in noisy environments.

The use of ultrasound in the study of articulatory properties of vowels in clear speech.

Although the acoustic properties of clear speech have been extensively studied, its underlying articulatory details have not been well understood. The purpose of the present study is twofold: To examine the specific articulatory processes of clear speech using ultrasound and to investigate whether and how the type of listener (hard of hearing, normal hearing) and the lexical property of words (frequency) interact in the production of clear speech. To this end, we examined productions of /ɑ/, /æ/ and /u/ from 16 speakers of US English. Overall, our ultrasound results suggested that the tongue's highest point moved in a direction that exaggerated the three vowels' phonological features, resulting in an expanded articulatory vowel space for the hard-of-hearing listener and low-frequency words. No interaction was found between the listener and word frequency, suggesting that the effects of word frequency hold constant across the two types of listeners.

An investigation of clear speech effects on articulatory kinematics in talkers with ALS.

Amyotrophic lateral sclerosis (ALS) affects the speech motor system and causes a substantial decline in intelligibility. Clear speech strategies have been found to benefit intelligibility in talkers with dysarthria and the purpose of this study was to examine clear speech effects on tongue, lip, and jaw movements in persons with ALS and healthy controls. For this purpose, participants produced 10 repetitions of the sentence 'I owe you a yoyo' using both habitual and clear speech. Movement variability as well as maximum speed, range, and duration of movement of the articulators were obtained for both conditions. The results show significantly lower jaw movement variability during habitual speech but greater variability for clear speech in ALS relative to controls. The kinematic data was consistent with expectations for individuals with dysarthria. Based on these results, clear speech may be considered a mode of speech that produces high movement variability in talkers with ALS.

The role of speech style, frequency, and density in recognition memory for spoken words.

What determines whether listeners remember a spoken word? The Effortfulness Hypothesis claims that memory is modulated by a word's intelligibility during real-time processing, while the Distinctiveness Hypothesis claims that it is modulated by a word's distinguishing characteristics. We tested these differing predictions using American English words that varied along three dimensions known to affect both intelligibility and distinctiveness: speech style (clear versus casual), frequency (high versus low), and neighborhood density (high versus low). In a recognition memory experiment, participants (n = 66) listened to a set of study words, and then gave yes/no judgments to indicate whether or not they had heard the word earlier. Results showed that those words which exhibited distinctive characteristics - whether due to clear speech style, low frequency, or low density - were remembered better. The finding supports the Distinctiveness Hypothesis, suggesting that our capacity for remembering words relies on their distinctiveness, rather than on our capacity for recognizing them in real time.

Syllable-rate-adjusted-modulation (SRAM) predicts clear and conversational speech intelligibility.

Introduction: Objectively predicting speech intelligibility is important in both telecommunication and human-machine interaction systems. The classic method relies on signal-to-noise ratios (SNR) to successfully predict speech intelligibility. One exception is clear speech, in which a talker intentionally articulates as if speaking to someone who has hearing loss or is from a different language background. As a result, at the same SNR, clear speech produces higher intelligibility than conversational speech. Despite numerous efforts, no objective metric can successfully predict the clear speech benefit at the sentence level. Methods: We proposed a Syllable-Rate-Adjusted-Modulation (SRAM) index to predict the intelligibility of clear and conversational speech. The SRAM used as short as 1 s speech and estimated its modulation power above the syllable rate. We compared SRAM with three reference metrics: envelope-regression-based speech transmission index (ER-STI), hearing-aid speech perception index version 2 (HASPI-v2) and short-time objective intelligibility (STOI), and five automatic speech recognition systems: Amazon Transcribe, Microsoft Azure Speech-To-Text, Google Speech-To-Text, wav2vec2 and Whisper. Results: SRAM outperformed the three reference metrics (ER-STI, HASPI-v2 and STOI) and the five automatic speech recognition systems. Additionally, we demonstrated the important role of syllable rate in predicting speech intelligibility by comparing SRAM with the total modulation power (TMP) that was not adjusted by the syllable rate. Discussion: SRAM can potentially help understand the characteristics of clear speech, screen speech materials with high intelligibility, and convert conversational speech into clear speech.

Effect of clear speech on acoustic measures of dysprosody in Parkinson disease for different reading tasks.

PURPOSE: The purpose of the study was to determine the effect of clear speech instruction on acoustic measures of dysprosody between reading passages of differing linguistic content for speakers with and without Parkinson Disease (PD). METHOD: Ten speakers with PD and 10 controls served as participants and read five simple and three standard reading stimuli twice. First, speakers read habitually and then following clear speech instruction. Acoustic measures of fundamental frequency variation (semitone standard deviation, STSD), articulation rate, and between-complex pause durations were calculated. RESULT: Results indicated speakers with PD exhibited less fundamental frequency variation than controls across reading stimuli and instructions. All speakers exhibited lower STSD and longer between-complex pause durations for the standard compared to simple reading stimuli. For clear speech, all speakers reduced articulation rate and increased between-complex pause durations in both simple and standard reading stimuli. However, speakers with PD exhibited a significantly less robust reduction in articulation rate for clear speech than control speakers for all reading stimuli. CONCLUSION: Linguistic content of reading stimuli contributes to differences in fundamental frequency variation and pause duration for all speakers. All speakers reduced articulation rate for clear speech compared to habitual instruction, but speakers with PD did so to a lesser extent than controls. Linguistic content of reading stimuli to examine dysprosody in PD should be considered for clinical application.

Multi-modal cross-linguistic perception of Mandarin tones in clear speech.

Clearly enunciated speech (relative to conversational, plain speech) involves articulatory and acoustic modifications that enhance auditory-visual (AV) segmental intelligibility. However, little research has explored clear-speech effects on the perception of suprasegmental properties such as lexical tone, particularly involving visual (facial) perception. Since tone production does not primarily rely on vocal tract configurations, tones may be less visually distinctive. Questions thus arise as to whether clear speech can enhance visual tone intelligibility, and if so, whether any intelligibility gain can be attributable to tone-specific category-enhancing (code-based) clear-speech cues or tone-general saliency-enhancing (signal-based) cues. The present study addresses these questions by examining the identification of clear and plain Mandarin tones with visual-only, auditory-only, and AV input modalities by native (Mandarin) and nonnative (English) perceivers. Results show that code-based visual and acoustic clear tone modifications, although limited, affect both native and nonnative intelligibility, with category-enhancing cues increasing intelligibility and category-blurring cues decreasing intelligibility. In contrast, signal-based cues, which are extensively available, do not benefit native intelligibility, although they contribute to nonnative intelligibility gain. These findings demonstrate that linguistically relevant visual tonal cues are existent. In clear speech, such tone category-enhancing cues are incorporated with saliency-enhancing cues across AV modalities for intelligibility improvements.

Effect of clear speech intervention program on speech intelligibility in persons with idiopathic Parkinson's disease: A pilot study.

Purpose: This preliminary study was designed to assess the feasibility of Clear Speech Intervention Program (CSIP) on improving speech intelligibility of persons with idiopathic Parkinson's disease (PD). Clear Speech is a behavioural approach which focuses on improving speech intelligibility of persons with PD within a relatively short frame of time.Method: A single group pretest-posttest design was used to assess the effectiveness of CSIP. Fifteen adults diagnosed with PD participated in 8 sessions of CSIP with each session lasting 45-50 minutes over a period of 4 weeks in South Korea. All the data were collected in a quiet room with an ambient noise level of equal to or less than 40 dB SPL. Data on acoustical/aerodynamic, auditory-perceptual, and self-perceptual measures were obtained pre- and post-intervention. The Phonatory Aerodynamic System (PAS) was used to analyse acoustical/aerodynamic data.Result: The acoustical/aerodynamic assessment revealed statistically significant (p < 0.01) improvements in habitual pitch, pitch range, speaking rate, and number of respirations. In the auditory-perceptual assessment, statistically significant (p < 0.01) improvements were observed in overall speech intelligibility, tone, intonation, intensity, and articulation. Medium to large effect sizes were observed for significant results. The Pearson correlation analysis showed significant (p < 0.01) and strong correlation between articulation and speech intelligibility.Conclusion: The preliminary data has provided promising results and warrants future large-scale studies with suitable controls. Additionally, future research must focus on investigating long term effects of the intervention.

Perceived Anger in Clear and Conversational Speech: Contributions of Age and Hearing Loss.

A previous investigation demonstrated differences between younger adult normal-hearing listeners and older adult hearing-impaired listeners in the perceived emotion of clear and conversational speech. Specifically, clear speech sounded angry more often than conversational speech for both groups, but the effect was smaller for the older listeners. These listener groups differed by two confounding factors, age (younger vs. older adults) and hearing status (normal vs. impaired). The objective of the present study was to evaluate the contributions of aging and hearing loss to the reduced perception of anger in older adults with hearing loss. We investigated perceived anger in clear and conversational speech in younger adults with and without a simulated age-related hearing loss, and in older adults with normal hearing. Younger adults with simulated hearing loss performed similarly to normal-hearing peers, while normal-hearing older adults performed similarly to hearing-impaired peers, suggesting that aging was the primary contributor to the decreased anger perception seen in previous work. These findings confirm reduced anger perception for older adults compared to younger adults, though the significant speaking style effect-regardless of age and hearing status-highlights the need to identify methods of producing clear speech that is emotionally neutral or positive.

Effects of Wearing Face Masks While Using Different Speaking Styles in Noise on Speech Intelligibility During the COVID-19 Pandemic.

The coronavirus pandemic has resulted in the recommended/required use of face masks in public. The use of a face mask compromises communication, especially in the presence of competing noise. It is crucial to measure the potential effects of wearing face masks on speech intelligibility in noisy environments where excessive background noise can create communication challenges. The effects of wearing transparent face masks and using clear speech to facilitate better verbal communication were evaluated in this study. We evaluated listener word identification scores in the following four conditions: (1) type of mask condition (i.e., no mask, transparent mask, and disposable face mask), (2) presentation mode (i.e., auditory only and audiovisual), (3) speaking style (i.e., conversational speech and clear speech), and (4) with two types of background noise (i.e., speech shaped noise and four-talker babble at -5 signal-to-noise ratio). Results indicate that in the presence of noise, listeners performed less well when the speaker wore a disposable face mask or a transparent mask compared to wearing no mask. Listeners correctly identified more words in the audiovisual presentation when listening to clear speech. Results indicate the combination of face masks and the presence of background noise negatively impact speech intelligibility for listeners. Transparent masks facilitate the ability to understand target sentences by providing visual information. Use of clear speech was shown to alleviate challenging communication situations including compensating for a lack of visual cues and reduced acoustic signals.

The Effect of Clear Speech on Temporal Metrics of Rhythm in Spanish-Accented Speakers of English.

This paper presents a comparative analysis of temporal rhythm in native American English talkers and Spanish-accented English talkers producing clear (hyperarticulated) speech and typical, conversational-style speech. Five acoustic measures of comparative vocalic and consonantal interval duration ("temporal metrics") were obtained from speech samples of 40 adult men and women (half native and half Spanish-accented talkers). In conversational-style speech, vocalic-based metrics differed significantly between native and Spanish-accented talkers, consistent with phonotactic differences between the two native languages. In clear speech, however, all metric values from the Spanish-accented talkers became more English-like and no longer differed significantly from those observed in the native English talkers. Post-hoc analysis revealed that native English talkers increased the duration of both weak and strong vowels in clear speech, whereas the Spanish-accented talkers increased the duration of strong vowels without changing the duration of weak vowels. Listener ease of understanding, as perceived by monolingual English speakers, was significantly improved in clear- compared with conversational-style speech for all talkers. The acoustic data help to explain the changes that result from use of clear speech in nonnative speakers. Together with the improved listener ease of understanding, these data strongly support the further exploration of clear speech as a clinical tool to improve prosody and hence, interpersonal communication, in nonnative speakers.

The influence of clear speech on auditory-perceptual judgments of electrolaryngeal speech.

PURPOSE: To determine the influence of clear speech on auditory-perceptual judgments of speech acceptability and listener comfort for electrolaryngeal speech. METHOD: Voice recordings were obtained from 10 electrolaryngeal speakers. Each speaker read the Rainbow Passage in two conditions: habitual speech and clear speech. Speakers were encouraged to speak as clearly as possible and over-articulate in the clear speech condition. Auditory-perceptual rating tasks were completed by 20 normal-hearing adults who evaluated 20 randomized voice recordings. Two counterbalanced listening sessions were used to gather ratings of speech acceptability and listener comfort. RESULTS: A significant effect of speaking condition was found on listener judgments of speech acceptability, but not listener comfort. However, listener scores for speech acceptability and listener comfort were found to be significantly related. For all speakers, objective temporal measures indicated reduced speaking rates in the clear speech condition. CONCLUSIONS: These findings suggest that volitional attempts to improve electrolaryngeal speech using clear speech might negatively impact listener judgments of speech acceptability, but not listener comfort. Further, the data suggest that speech acceptability and listener comfort might address unique perceptual entities. Overall, the strong relationship between these auditory-perceptual dimensions provide support for the use of scaled measurements to assess the impact of speech rehabilitation on individuals who use the electrolarynx.

Articulatory-acoustic vowel space: Associations between acoustic and perceptual measures of clear speech.

PURPOSE: The current investigation examined the relationship between perceptual ratings of speech clarity and acoustic measures of speech production. Included among the acoustic measures was the Articulatory-Acoustic Vowel Space (AAVS), which provides a measure of working formant space derived from continuously sampled formant trajectories in connected speech. METHOD: Acoustic measures of articulation and listener ratings of speech clarity were obtained from habitual and clear speech samples produced by 10 neurologically healthy adults. Perceptual ratings of speech clarity were obtained from visual-analogue scale ratings and acoustic measures included the AAVS measure, articulation rate and percentage pause. RESULT: Clear speech was characterised by a higher perceptual clarity rating, slower articulation rate, greater percentage pause and larger AAVS compared to habitual speech. Additionally, correlation analysis revealed a significant relationship between the perceptual clear speech effect and the relative clarity-related change in the AAVS and articulation rate measures. CONCLUSION: The current findings suggest that, along with speech rate measures, the recently introduced AAVS is sensitive to changes in speech clarity.

Articulatory-acoustic vowel space: application to clear speech in individuals with Parkinson's disease.

BACKGROUND/PURPOSE: Individuals with Parkinson disease (PD) often exhibit decreased range of movement secondary to the disease process, which has been shown to affect articulatory movements. A number of investigations have failed to find statistically significant differences between control and disordered groups, and between speaking conditions, using traditional vowel space area measures. The purpose of the current investigation was to evaluate both between-group (PD versus control) and within-group (habitual versus clear) differences in articulatory function using a novel vowel space measure, the articulatory-acoustic vowel space (AAVS). METHODS: The novel AAVS is calculated from continuously sampled formant trajectories of connected speech. In the current study, habitual and clear speech samples from twelve individuals with PD along with habitual control speech samples from ten neurologically healthy adults were collected and acoustically analyzed. In addition, a group of listeners completed perceptual rating of speech clarity for all samples. RESULTS: Individuals with PD were perceived to exhibit decreased speech clarity compared to controls. Similarly, the novel AAVS measure was significantly lower in individuals with PD. In addition, the AAVS measure significantly tracked changes between the habitual and clear conditions that were confirmed by perceptual ratings. CONCLUSIONS: In the current study, the novel AAVS measure is shown to be sensitive to disease-related group differences and within-person changes in articulatory function of individuals with PD. Additionally, these data confirm that individuals with PD can modulate the speech motor system to increase articulatory range of motion and speech clarity when given a simple prompt. LEARNING OUTCOMES: The reader will be able to (i) describe articulatory behavior observed in the speech of individuals with Parkinson disease; (ii) describe traditional measures of vowel space area and how they relate to articulation; (iii) describe a novel measure of vowel space, the articulatory-acoustic vowel space and its relationship to articulation and the perception of speech clarity.

Intelligibility of clear speech: effect of instruction.

PURPOSE: The authors investigated how clear speech instructions influence sentence intelligibility. METHOD: Twelve speakers produced sentences in habitual, clear, hearing impaired, and overenunciate conditions. Stimuli were amplitude normalized and mixed with multitalker babble for orthographic transcription by 40 listeners. The main analysis investigated percentage-correct intelligibility scores as a function of the 4 conditions and speaker sex. Additional analyses included listener response variability, individual speaker trends, and an alternate intelligibility measure: proportion of content words correct. RESULTS: Relative to the habitual condition, the overenunciate condition was associated with the greatest intelligibility benefit, followed by the hearing impaired and clear conditions. Ten speakers followed this trend. The results indicated different patterns of clear speech benefit for male and female speakers. Greater listener variability was observed for speakers with inherently low habitual intelligibility compared to speakers with inherently high habitual intelligibility. Stable proportions of content words were observed across conditions. CONCLUSIONS: Clear speech instructions affected the magnitude of the intelligibility benefit. The instruction to overenunciate may be most effective in clear speech training programs. The findings may help explain the range of clear speech intelligibility benefit previously reported. Listener variability analyses suggested the importance of obtaining multiple listener judgments of intelligibility, especially for speakers with inherently low habitual intelligibility.

Tongue-palate contact pressure, oral air pressure, and acoustics of clear speech.

PURPOSE: The authors compared articulatory contact pressure (ACP), oral air pressure (Po), and speech acoustics for conversational versus clear speech. They also assessed the relationship of these measures to listener perception. METHOD: Twelve adults with normal speech produced monosyllables in a phrase using conversational and clear speech. Target phonemes were /t, d, s, z, l, n/. ACP was measured at a point of articulatory contact; Po was sensed by a catheter open in the posterior oral cavity. RESULTS: ACP was increased to a greater extent in clear speech for /t, d, z/. Po was increased to a greater extent for /t, d/. Acoustic changes also occurred in terms of segment durations, speaking rate, and CV dB ratio. Regression analysis indicated that segment duration was the strongest predictor of listener ratings of speech clarity, followed by an index of articulatory effort and speaking rate. CONCLUSION: Articulatory effort, as indexed by ACP, Po, and CV dB ratio, was increased to varying degrees depending on the consonant. Greatest changes occurred for /t, d/. Durational measures at both the segment and the phrase level were also important for predicting listener ratings of speech clarity.