The listening talker: A review of human and algorithmic context-induced modifications of speech

International audienceSpeech output technology is finding widespread application, including in scenarios where intelligibility might be compromised - at least for some listeners - by adverse conditions. Unlike most current algorithms, talkers continually adapt their speech patterns as a response to the immediate context of spoken communication, where the type of interlocutor and the environment are the dominant situational factors influencing speech production. Observations of talker behaviour can motivate the design of more robust speech output algorithms. Starting with a listener-oriented categorisation of possible goals for speech modification, this review article summarises the extensive set of behavioural findings related to human speech modification, identifies which factors appear to be beneficial, and goes on to examine previous computational attempts to improve intelligibility in noise. The review concludes by tabulating 46 speech modifications, many of which have yet to be perceptually or algorithmically evaluated. Consequently, the review provides a roadmap for future work in improving the robustness of speech output

Asymmetrical cognitive load Imposed by processing native and non-native speech

Intonation affects information processing and comprehension. Previous research has found that some international teaching assistants (ITAs) fail to exploit English intonation, potentially posing processing difficulties to students who are native English speakers. However, researchers have also found that non-native listeners found it easier to process sentences given by a non-native speaker with a shared language background, leading to an interlanguage speech intelligibility benefit (ISIB). Therefore, how native speaker teaching assistant (NSTA)’s and ITA’s classroom speech affects the processing, comprehension, and attitudes of listeners with different language backgrounds needs to be further investigated. Using a dual-task paradigm, a comprehension questionnaire, and an attitudinal questionnaire, the present study investigates how the pronunciation and intonation of a NSTA and an ITA affect native English speakers’ and Mandarin-speaking English learners’ processing and comprehension of a lecture, and attitudes towards the two instructors. The present study found shared processing advantages when the listeners shared the L1 of the speaker, but overall lecture comprehension and attitude were unaffected. These findings support and extend prior research studies surveying ITAs’ intonational patterns and ISIB. These findings also have implications for research on the teaching of English pronunciation to non-native instructors.Published versio

The effects of delayed and frequency shifted feedback on speakers with Parkinson disease

Delayed auditory feedback (DAF) has been assessed as a rate reduction and intelligibility enhancing tool in patients with Parkinson disease (PD) for some time. However, there are contradictory results in the literature regarding the success of this device. Also, little is known about the effects of DAF on speech other than influences on speech rate and intelligibility. Frequency shifted feedback (FSF) is known to produce more natural sounding speech than DAF and to improve the fluency of persons who stutter. However, there are currently no studies reporting how PD speakers perform under FSF. The aim of this study was to investigate the effects of both types of altered feedback on the speech of PD and control participants on a broad range of measures. The performance of 16 PD speakers and 11 control speakers in a reading task under DAF, FSF, and no altered feedback (NAF) are reported here. The results showed that all groups responded to altered feedback in a similar way and showed a prominent reduction of speech rate. The conditions evoked changes in pause frequency (increases), loudness levels (increases), pitch variation (increases), and intelligibility and naturalness (decreases) for all or some of the groups. Few effects could be observed on articulation/pause time ratio, pause duration, pitch range, and speech rhythm. Previous reports on differences in susceptibility of PD speaker to altered feedback were confirmed, and some speakers benefited from the system despite the negative group results for intelligibility and naturalness. In general, FSF resulted in performance closer to the NAF state than to DAF on all variables, and for those PD speakers who benefited from altered feedback, the FSF condition evoked the greatest improvement

Native Speaker Perceptions of Accented Speech: The English Pronunciation of Macedonian EFL Learners

The paper reports on the results of a study that aimed to describe the vocalic and consonantal features of the English pronunciation of Macedonian EFL learners as perceived by native speakers of English and to find out whether native speakers who speak different standard variants of English perceive the same segments as non-native. A specially designed computer web application was employed to gather two types of data: a) quantitative (frequency of segment variables and global foreign accent ratings on a 5-point scale), and b) qualitative (open-ended questions). The result analysis points out to three most frequent markers of foreign accent in the English speech of Macedonian EFL learners: final obstruent devoicing, vowel shortening and substitution of English dental fricatives with Macedonian dental plosives. It also reflects additional phonetic aspects poorly explained in the available reference literature such as allophonic distributional differences between the two languages and intonational mismatch

Production and perception of speaker-specific phonetic detail at word boundaries

Experiments show that learning about familiar voices affects speech processing in many tasks. However, most studies focus on isolated phonemes or words and do not explore which phonetic properties are learned about or retained in memory. This work investigated inter-speaker phonetic variation involving word boundaries, and its perceptual consequences. A production experiment found significant variation in the extent to which speakers used a number of acoustic properties to distinguish junctural minimal pairs e.g. 'So he diced them'—'So he'd iced them'. A perception experiment then tested intelligibility in noise of the junctural minimal pairs before and after familiarisation with a particular voice. Subjects who heard the same voice during testing as during the familiarisation period showed significantly more improvement in identification of words and syllable constituents around word boundaries than those who heard different voices. These data support the view that perceptual learning about the particular pronunciations associated with individual speakers helps listeners to identify syllabic structure and the location of word boundaries

Stop Release in Polish English — Implications for Prosodic Constituency

Although there is little consensus on the relevance of non-contrastive allophonic processes in L2 speech acquisition, EFL pronunciation textbooks cover the suppression of stop release in coda position. The tendency for held stops in English is in stark opposition to a number of other languages, including Polish, in which plosive release is obligatory. This paper presents phonetic data on the acquisition of English unreleased stops by Polish learners. Results show that in addition to showing a tendency for the target language pattern of unreleased plosives, advanced learners may acquire more native-like VC formant transitions. From the functional perspective, languages with unreleased stops may be expected to have robust formant patterns on the final portion of the preceding vowel, which allow listeners to identify the final consonant when it lacks an audible release burst (see e.g. Wright 2004). From the perspective of syllabic positions, it may be said that ‘coda’ stops are obligatorily released in Polish, yet may be unreleased in English. Thus, the traditional term ‘coda’ is insufficient to describe the prosodic properties of post-vocalic stops in Polish and English. These differences may be captured in the Onset Prominence framework (Schwartz 2013). In languages with unreleased stops, the mechanism of submersion places post-vocalic stops at the bottom of the representational hierarchy where they may be subject to weakening. Submersion produces larger prosodic constituents and thus has phonological consequences beyond ‘coda’ behavior

Characterizing intonation deficit in motor speech disorders : an autosegmental-metrical analysis of spontaneous speech in hypokinetic dysarthria, ataxic dysarthria and foreign accent syndrome

The autosegmental-metrical (AM) framework represents an established methodology for intonational analysis in unimpaired speaker populations but has found little application in describing intonation in motor speech disorders (MSDs). This study compared the intonation patterns of unimpaired participants (CON) and those with Parkinson's disease (PD), ataxic dysarthria (AT), and foreign accent syndrome (FAS) to evaluate the approach's potential for distinguishing types of MSDs from each other and from unimpaired speech. Spontaneous speech from 8 PD, 8 AT, 4 FAS, and 10 CON speakers were analyzed in relation to inventory and prevalence of pitch patterns, accentuation, and phrasing. Acoustic-phonetic baseline measures (maximum-phonation-duration, speech rate, and F0-variability) were also performed. Results: The analyses yielded differences between MSD and CON groups and between the clinical groups in regard to prevalence, accentuation, and phrasing. AT and FAS speakers used more rising and high pitch accents than PD and CON speakers. The AT group used the highest number of pitch accents per phrase, and all 3 MSD groups produced significantly shorter phrases than the CON group. The study succeeded in differentiating MSDs on the basis of intonational performances by using the AM approach, thus, demonstrating its potential for charting intonational profiles in clinical populations

Speech and language therapy versus placebo or no intervention for speech problems in Parkinson's disease

Parkinson's disease patients commonly suffer from speech and vocal problems including dysarthric speech, reduced loudness and loss of articulation. These symptoms increase in frequency and intensity with progression of the disease). Speech and language therapy (SLT) aims to improve the intelligibility of speech with behavioural treatment techniques or instrumental aids