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The present study investigates the relationship between sentence intelligibility, band importance, and patterns of spectro-temporal covariation between frequency bands. Sixteen listeners transcribed sentences acoustically degraded to 5, 8, or 15 frequency bands. Half of the sentences retained the frequency bands that captured more signal covariance. The other half retained the bands accounting for less signal covariance. Sentence intelligibility was significantly higher in the high-covariance condition. Critically, this finding was predicted by differences in band importance across reconstructed sentences. These findings provide a mechanistic relationship between the contributions of signal covariance and band importance to sentence intelligibility.

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.

Though necessary, protective mask wearing in response to the COVID-19 pandemic presents communication challenges. The present study examines how signal degradation and loss of visual information due to masks affects intelligibility and memory for native and non-native speech. We also test whether clear speech can alleviate perceptual difficulty for masked speech. One native and one non-native speaker of English recorded video clips in conversational speech without a mask and conversational and clear speech with a mask. Native English listeners watched video clips presented in quiet or mixed with competing speech. The results showed that word recognition and recall of speech produced with a mask can be as accurate as without a mask in optimal listening conditions. Masks affected non-native speech processing at easier noise levels than native speech. Clear speech with a mask significantly improved accuracy in all listening conditions. Speaking clearly, reducing noise, and using surgical masks as well as good signal amplification can help compensate for the loss of intelligibility due to background noise, lack of visual cues, physical distancing, or non-native speech. The findings have implications for communication in classrooms and hospitals where listeners interact with teachers and healthcare providers, oftentimes non-native speakers, through their protective barriers.

Speech signals are acoustically redundant, which could explain why sentence intelligibility is fairly robust even when sentences are acoustically degraded. We investigated the contributions to sentence intelligibility of clear speech redundancy encoded as patterns of spectrotemporal covariation between frequency channels. Participants (N = 16) transcribed 120 clear-speech English sentences acoustically degraded to 5, 8, or 15 frequency bands derived from an ERB-scaled filter bank. Before the acoustic degradation, each sentence was expressed as a linear combination of principal component eigenvectors representing different patterns of covariation between channels. Half of the sentences preserved the channels providing larger score magnitudes for the eigenvector accounting for more spectral covariance (high-covariance condition). These channels represented the spectral covariation patterns that were more dominant in each sentence. The other half of the sentences preserved the bands conveying larger score magnitudes for the eigenvector accounting forless spectral covariance (low-covariance condition). These bands represented the spectral covariation patterns that were less dominant. Participants yielded significantly better transcription accuracy in the high-covariance condition (mixed-effects, ps

Listeners are able to classify talkers by regional dialect of their native language when provided with even short speech samples. However, the way in which American English listeners use segmental and prosodic information to make such decisions is largely unknown. This study used a free classification task to assess native American English listeners' ability to group together talkers from six major dialect regions of American English. Listeners residing in Ohio and Texas were provided with a sentence-long (experiment 1) or paragraph-long (experiment 2) speech sample produced by talkers from each of the six regions presented in one of three conditions: unmodified, monotonized (i.e., flattened F0), and low-pass filtered (i.e., spectral information above 400 Hz removed). In both experiments, listeners in the unmodified and monotonized conditions made more accurate groupings, reflecting their reliance on segmental properties for classifying regional variation. Accuracy was highest for Northern and Western talkers (experiment 1) and Mid-Atlantic talkers (experiment 2). Listeners with experience with multiple dialects as a result of geographic mobility did not show increased accuracy, suggesting a complex relationship between linguistic experience and the perception of available acoustic cues to socioindexical variation.

Though necessary, protective mask wearing in response to the Covid-19 pandemic presents communication challenges. Speech produced through these masks is quieter, muffled, and lacks important visual cues for listeners. The present study examines how such loss of visual information and signal degradation affects intelligibility and auditory memory of non-native speech. Additionally, we examined whether clear speaking style can alleviate some perceptual difficulty for masked speech. One non-native English speaker recorded short, educationally relevant video clips in three conditions: casual speech without a mask, and casual and clear speech with a mask. In an online study, native English listeners were presented with 15 video clips in each of the three mask / style conditions and transcribed what they heard. Following each condition, listeners answered questions about the content of the clips. Word recognition and memory accuracy will be analyzed. Detailed acoustic analyses will be conducted to assess how face masks and speaking style affect speech production. The results will allow us to quantify speech communication challenges arising from the widespread use of masks. The findings will have implications for communication in classrooms and hospitals where listeners have to understand teachers and healthcare providers, often time non-native speakers, through their protective barriers.

Listening effort increases when perceiving speech masked by noise and when listeners are non-native speakers of the target language (Zekveld and Kramer, 2014; Borghini and Hazan, 2018). Listener-oriented clear speech (CS) improves word recognition in noise and recognition memory (Keerstock and Smiljanic, 2018). It is unclear, however, whether the CS benefit can be explained by reduced listening effort during processing of easier-to-understand speech. The goal of this study was to examine the effect of CS on listening effort associated with degraded listening conditions differing in the source of difficulty and underlying cognitive mechanism: energetic masking, informational masking, and non-native listening. Native and non-native English listeners performed a word recognition in noise task and a visual response task, i.e., pressing keys to indicate the orientation of an arrow on the screen, first separately and then simultaneously. In the word recognition task, listeners repeated back sentences produced in CS and conversational speech and mixed with speech-shaped noise and 2-talker babble. The presentation will discuss analyses aimed at uncovering how hyper-articulated CS and masker type influence listening effort for native and non-native listeners as measured by objective and subjective dual-task cost.

This paper focuses on the controversies surrounding the effect of linguistic input in language acquisition and investigates how learning of a dialectal pattern, a-prefixing in Appalachian English, can be modulated by positive vs. negative evidence in adult learners whose grammar does not contain this grammatical phenomenon. In an online acceptability judgment study, we measured gradient grammatical intuitions of 41 Appalachian English and 36 native speakers of American English on their perceived acceptability of carefully-matched grammatical and ungrammatical sentences with a-prefixing. We used 16 sentences (50% ungrammatical) for each of the 5 previously established constraints on a-prefixing, divided equally into a pre- and post-test session. The non-dialect speakers were further divided into 3 input groups depending on the type of input they received between the two tests: the positive-evidence group with only grammatical instances of a-prefixing, the negative-evidence group with explicit instruction concerning only ungrammaticality, and the control group with no input. Results indicated that, just like the baseline Appalachian English group, the non-dialect participants were able to distinguish grammatical sentences from ungrammatical ones, crucially in all of the 5 different constraints, prior to the treatment, although they significantly differed from the Appalachian English group in the strength of their judgments. The post-test results revealed a clear benefit of negative evidence on the learning of a novel grammatical phenomenon, albeit only concerning the responses to ungrammatical sentences, while accept-ability judgments for grammatical as well as ungrammatical sentences did not benefit from positive evidence alone. We suggest that the target-like intuitions of our non-dialect participants at the onset result from a deduction of tacitly known principles of English and linguistic universals. Concerning the differential effect of input categories on learning, we argue that exposure to only positive exemplars of the target phenomenon results in overly general hypotheses about its patterning in the language, which may push the learner to perceive new ungrammatical sentences better than their initial acceptability value. Negative exemplars, however, place a pressure on learners to notice the linguistic contexts in which the target phenomenon is not allowed to surface, thereby raising their awareness of the presence of rules.

It is well established that native listeners outperform non-native listeners on word recognition tasks involving both speech-shaped noise (SSN) and competing speech (speech babble). The present study examined whether this non-native disadvantage can be compensated for by speaking style enhancements. We also explored how these acoustic-articulatory modifications interact with energetic and informational masking at different signal-to-noise ratios to determine intelligibility for the two listener groups. Native and non-native participants heard noise-adapted (NAS) and clear speech (CL) sentences mixed with either SSN, two-talker (2T), or six-talker (6T) babble. CL and NAS significantly improved word recognition in noise, but native listeners were better able to use the intelligibility-enhancing modifications. Results revealed an interaction between noise type and SNR such that the intelligibility gain was larger for SSN at an easier SNR, but for 6T babble at a harder SNR. The speaking style modifications en...

It is well established that non-native listeners perform worse on speech perception in noise tasks compared to native listeners. However, few studies have directly compared the effect of speaking style adaptations on speech perception in energetic and informational maskers for these two listener groups. The present study examined intelligibility of conversational (CO), clear (CS) and noise-adapted (NAS) meaningful sentences mixed with speech shaped noise (SSN) and 2-talker (2T) babble. Sentences were presented at −5 dB signal to noise ratio (SNR) to native and −3 dB SNR to non-native listeners. The results revealed that CS and NAS significantly improved word recognition in noise for both listener groups. However, the gains in intelligibility were substantially greater for native compared to non-native listeners. Word recognition was overall better in 2T babble than in SSN. Our findings confirm that both native and non-native listeners benefited from speaking style adjustments, but native listeners were be...