A targeted review of prosodic production in agrammatic aphasia.

It is unclear whether individuals with agrammatic aphasia have particularly disrupted prosody, or in fact have relatively preserved prosody they can use in a compensatory way. A targeted literature review was undertaken to examine the evidence regarding the capacity of speakers with agrammatic aphasia to produce prosody. The aim was to answer the question, how much prosody can a speaker "do" with limited syntax? The literature was systematically searched for articles examining the production of grammatical prosody in people with agrammatism, and yielded 16 studies that were ultimately included in this review. Participant inclusion criteria, spoken language tasks, and analysis procedures vary widely across studies. The evidence indicates that timing aspects of prosody are disrupted in people with agrammatic aphasia, while the use of pitch and amplitude cues is more likely to be preserved in this population. Some, but not all, of these timing differences may be attributable to motor speech programming deficits (AOS) rather than aphasia, as these conditions frequently co-occur. Many of the included studies do not address AOS and its possible role in any observed effects. Finally, the available evidence indicates that even speakers with severe aphasia show a degree of preserved prosody in functional communication.

Lexical and syntactic gemination in Italian consonants-Does a geminate Italian consonant consist of a repeated or a strengthened consonant?

Two types of consonant gemination characterize Italian: lexical and syntactic. Italian lexical gemination is contrastive, so that two words may differ by only one geminated consonant. In contrast, syntactic gemination occurs across word boundaries and affects the initial consonant of a word in specific contexts, such as the presence of a monosyllabic morpheme before the word. This study investigates the acoustic correlates of Italian lexical and syntactic gemination, asking if the correlates for the two types are similar in the case of stop consonants. Results confirmed previous studies showing that duration is a prominent gemination cue, with a lengthened consonant closure and a shortened pre-consonant vowel for both types. Results also revealed the presence, in about 10%-12% of instances, of a double stop-release burst, providing strong support for the biphonematic nature of Italian geminated stop consonants. Moreover, the timing of these bursts suggests a different planning process for lexical vs syntactic geminates. The second burst, when present, is accommodated within the closure interval in syntactic geminates, while lexical geminates are lengthened by the extra burst. This suggests that syntactic gemination occurs during a post-lexical phase of production planning, after timing has already been established.

A landmark-cue-based approach to analyzing the acoustic realizations of American English intervocalic flaps.

This study examines the acoustic realizations of American English intervocalic flaps in the TIMIT corpus, using the landmark-critical feature-cue-based framework. Three different acoustic patterns of flaps are described: (i) both closure and release landmarks present, (ii) only the closure landmark present, and (iii) both landmarks deleted. The patterns occur consistently across several phonological and morphological conditions but vary with sociolinguistic factors, including speaker dialect and gender. This method of analysing speech at the level of acoustic landmarks and other individual cues to distinctive features contributes to a deeper understanding of how speakers and listeners employ systematic variation in phonetic detail in speech processing.

A framework for labeling speech with acoustic cues to linguistic distinctive features.

Acoustic cues are characteristic patterns in the speech signal that provide lexical, prosodic, or additional information, such as speaker identity. In particular, acoustic cues related to linguistic distinctive features can be extracted and marked from the speech signal. These acoustic cues can be used to infer the intended underlying phoneme sequence in an utterance. This study describes a framework for labeling acoustic cues in speech, including a suite of canonical cue prediction algorithms that facilitates manual labeling and provides a standard for analyzing variations in the surface realizations. A brief examination of subsets of annotated speech data shows that labeling acoustic cues opens the possibility of detailed analyses of cue modification patterns in speech.

Identifying a creak probability threshold for an irregular pitch period detection algorithm.

Irregular pitch periods (IPPs) are associated with grammatically, pragmatically, and clinically significant types of nonmodal phonation, but are challenging to identify. Automatic detection of IPPs is desirable because accurately hand-identifying IPPs is time-consuming and requires training. The authors evaluated an algorithm developed for creaky voice analysis to automatically identify IPPs in recordings of American English conversational speech. To determine a perceptually relevant threshold probability, frame-by-frame creak probabilities were compared to hand labels, yielding a threshold of approximately 0.02. These results indicate a generally good agreement between hand-labeled IPPs and automatic detection, calling for future work investigating effects of linguistic and prosodic context.

Towards the Quantification of Peggy Babcock: Speech Errors and Their Position within the Word.

Sequences of similar (i.e., partially identical) words can be hard to say, as indicated by error frequencies, longer reaction and execution times. This study investigates the role of the location of this partial identity and the accompanying differences, i.e. whether errors are more frequent with mismatches in word onsets (top cop), codas (top tock) or both (pop tot). Number of syllables (tippy ticky) and empty positions (top ta) were also varied. Since the gradient nature of errors can be difficult to determine acoustically, articulatory data were investigated. Articulator movements were recorded using electromagnetic articulography, for up to 9 speakers of American English repeatedly producing 2-word sequences to an accelerating metronome. Most word pairs showed more intrusions and greater variability in coda than in onset position, in contrast to the predominance of onset position errors in corpora from perceptual observation.

Durational cues to fricative codas in 2-year-olds' American English: voicing and morphemic factors.

In the process of phonological development, fricatives are generally assumed to be later acquired than stops. However, most of the observational work on which this claim is based has concerned itself with word-initial onset consonants; little is known about how and when fricatives are mastered in word-final coda position (e.g., nose). This is all the more critical in a language like English, where word-final fricatives often carry important morphological information (e.g., toes, goes). This study examines the development of duration cues to the voicing feature contrast in coda fricatives, using longitudinal spontaneous speech data from CVC words (e.g., noise vs face) produced by three children (1;6-2;6 years) and six mothers. Results show that the children were remarkably adult-like in the use of duration cues to voicing contrasts in fricatives even in this early age range. Furthermore the children, like the mothers, had longer frication noise durations for morphemic compared to non-morphemic fricatives (e.g., toes vs nose) when these segments occurred in utterance-final position. These results suggest that although children's fricatives tend to be overall longer and more voiced compared to those of adults, the voicing and morphological contrasts for fricative codas are acquired early in production.

The Effect of Prosodic Timing Structure on Unison Production in People With Aphasia.

PURPOSE: Unison production is a common aphasia treatment technique in which the clinician and the person with aphasia (PWA) produce phrases aloud together. It can be implemented using a typical "conversational," syntax-influenced prosodic timing structure, or with a "metrical," beat-based timing structure, but to date no study has directly compared these two approaches. This study compared the effects of metrical versus conversational prosodic timing during unison production on the (a) accuracy of participants' spoken output and (b) timing alignment of participants' productions with the stimuli. METHOD: PWAs and controls listened to conversationally timed and metrically timed sentences and repeated them in unison with audio recordings. Productions were transcribed and scored in two ways: (a) Accuracy was calculated as the percentage of correctly produced syllables, and (b) timing alignment was determined by extracting the voice onset moment of identical target syllables in the unison stimuli and participant productions in both conditions and comparing the corresponding time points. RESULTS: Metrical timing yielded a greater number of accurate syllables in both groups, with larger effect in PWAs than in controls. Both groups exhibited more anticipatory, less variable timing when speaking along with metrical stimuli, though evidence of such prediction was also present in the conversational condition. CONCLUSIONS: Results suggest that unison production works via entrainment-a process that utilizes prediction to guide synchronous production of spoken output. Metrically regular stimuli may facilitate this process as they are more rhythmically predictable. Future work will examine key behavioral variables that predict benefit from unison production and metrical timing.

The development of acoustic cues to coda contrasts in young children learning American English.

Research on children's speech perception and production suggests that consonant voicing and place contrasts may be acquired early in life, at least in word-onset position. However, little is known about the development of the acoustic correlates of later-acquired, word-final coda contrasts. This is of particular interest in languages like English where many grammatical morphemes are realized as codas. This study therefore examined how various non-spectral acoustic cues vary as a function of stop coda voicing (voiced vs. voiceless) and place (alveolar vs. velar) in the spontaneous speech of 6 American-English-speaking mother-child dyads. The results indicate that children as young as 1;6 exhibited many adult-like acoustic cues to voicing and place contrasts, including longer vowels and more frequent use of voice bar with voiced codas, and a greater number of bursts and longer post-release noise for velar codas. However, 1;6-year-olds overall exhibited longer durations and more frequent occurrence of these cues compared to mothers, with decreasing values by 2;6. Thus, English-speaking 1;6-year-olds already exhibit adult-like use of some of the cues to coda voicing and place, though implementation is not yet fully adult-like. Physiological and contextual correlates of these findings are discussed.

The LaMIT database: A read speech corpus for acoustic studies of the Italian language toward lexical access based on the detection of landmarks and other acoustic cues to features.

The LaMIT database consists in recordings of 100 Italian sentences. The sentences in the database were designed so to include all phonemes of the Italian language, and also take into account the typical frequency of each phoneme in written Italian. Four native adult speakers of Standard Italian, raised and living in Rome, Italy, two female and two male, pronounced the sentences in two different recording sessions; two repetitions for each sentence per speaker were therefore collected, for a total of 800 recordings. The database was specifically created for application in the LaMIT project, that focuses on the application to the Italian language of the Lexical Access model proposed by Ken Stevens for American English. The model relies on the detection of specific acoustic discontinuities called landmarks and other acoustic cues to features that characterize each phoneme. Each recording was thus processed to generate a set of labeling files that identify both predicted landmarks and other cues, and actual landmarks/cues. The labeling files, compiled according to the labeling syntax used in the Praat speech processing software, are also made available as part of the LAMIT database.

Do listeners store in memory a speaker's habitual utterance--final phonation type?

Earlier studies report systematic differences across speakers in the occurrence of utterance-final irregular phonation; the work reported here investigated whether human listeners remember this speaker-specific information and can access it when necessary (a prerequisite for using this cue in speaker recognition). Listeners personally familiar with the voices of the speakers were presented with pairs of speech samples: one with the original and the other with transformed final phonation type. Asked to select the member of the pair that was closer to the talker's voice, most listeners tended to choose the unmanipulated token (even though they judged them to sound essentially equally natural). This suggests that utterance-final pitch period irregularity is part of the mental representation of individual speaker voices, although this may depend on the individual speaker and listener to some extent.

Timing Evidence for Symbolic Phonological Representations and Phonology-Extrinsic Timing in Speech Production.

The goals of this paper are (1) to discuss the key features of existing articulatory models of speech production that govern their approaches to timing, along with advantages and disadvantages of each, and (2) to evaluate these features in terms of several pieces of evidence from both the speech and nonspeech motor control literature. This evidence includes greater timing precision at movement endpoints compared to other parts of movements, suggesting the separate control of the timing of movement endpoints compared to other parts of movement. This endpoint timing precision challenges models in which all parts of a movement trajectory are controlled by the same equation of motion, but supports models in which (a) abstract, symbolic phonological representations map onto spatial and temporal characteristics of the part(s) of movement most closely related to the goal of producing a planned set of acoustic cues to signal the phonological contrast (often the endpoint), (b) movements are coordinated primarily based on the goal-related part of movement, and (c) speakers give priority to the accurate implementation of the part(s) of movement most closely related to the phonological goals. In addition, this paper presents three types of evidence for phonology-extrinsic timing, suggesting that surface duration requirements are represented during speech production. Phonology-extrinsic timing is also supported by greater timing variability for repetitions of longer intervals, assumed to be due to noise in a general-purpose (and phonology-extrinsic) timekeeping process. The evidence appears to be incompatible with models that have a unified Phonology/Phonetics Component, that do not represent the surface timing of phonetic events, and do not represent, specify and track timing by general-purpose timekeeping mechanisms. Taken together, this evidence supports an alternative approach to modeling speech production that is based on symbolic phonological representations and general-purpose, phonology-extrinsic, timekeeping mechanisms, rather than on spatio-temporal phonological representations and phonology-specific timing mechanisms. Thus, the evidence suggests that models in that alternative framework should be developed, so they can be tested with the same rigor as have models based on spatio-temporal phonological representations with phonology-intrinsic timing.

Phonetic relevance and phonemic grouping of speech in the automatic detection of Parkinson's Disease.

Literature documents the impact of Parkinson's Disease (PD) on speech but no study has analyzed in detail the importance of the distinct phonemic groups for the automatic identification of the disease. This study presents new approaches that are evaluated in three different corpora containing speakers suffering from PD with two main objectives: to investigate the influence of the different phonemic groups in the detection of PD and to propose more accurate detection schemes employing speech. The proposed methodology uses GMM-UBM classifiers combined with a technique introduced in this paper called phonemic grouping, that permits observation of the differences in accuracy depending on the manner of articulation. Cross-validation results reach accuracies between 85% and 94% with AUC ranging from 0.91 to 0.98, while cross-corpora trials yield accuracies between 75% and 82% with AUC between 0.84 and 0.95, depending on the corpus. This is the first work analyzing the generalization properties of the proposed approaches employing cross-corpora trials and reaching high accuracies. Among the different phonemic groups, results suggest that plosives, vowels and fricatives are the most relevant acoustic segments for the detection of PD with the proposed schemes. In addition, the use of text-dependent utterances leads to more consistent and accurate models.

The Prosodic Characteristics of Non-referential Co-speech Gestures in a Sample of Academic-Lecture-Style Speech.

Many studies have documented a close timing relationship between speech prosody and co-speech gesture, but some studies have not, and it is unclear whether these differences in speech-gesture alignment are due to different speaking tasks, different target gesture types, different prosodic elements, different definitions of alignment, or even different languages/speakers. This study contributes to the ongoing effort to elucidate the precise nature of the gesture-speech timing relationship by examining an understudied variety of American English, i.e., academic-lecture-style speech, with a focus on an understudied type of gesture: Non-Referential gestures, which make up the majority of this corpus. Results for the 1,334 Stroke-Defined Gestures in this 20-min sample suggest that the stroke phase of a Non-Referential gesture tends to align with a pitch-accented syllable, just as reported in studies of other gesture types (e.g., deictic gestures) and in other speaking styles (such as narration). Preliminary results are presented suggesting that trajectory shapes of these Non-Referential gestures are consistent across a higher-level prosodic grouping, supporting earlier proposals for kinematic constancy across spoken prosodic constituents (Kendon, 1972, 1980, 2004). Analysis also raises the possibility that the category of Non-Referential gestures is not solely made up of 'beats,' defined as simple bi-phasic flick-like movements that beat out the rhythm of the speech, but includes gestures with multiple phases and various types of rhythmicity. Taken together, the results of this analysis suggest (1) a wide range of gesture configurations within the undifferentiated category of Non-Referential gestures or 'beats,' which requires further investigation, and (2) a close coordination between co-speech gestures and the prosodic structure of spoken utterances across speaking styles and gesture referentiality, which has profound implications for modeling the process of planning an utterance.

English-learning infants' segmentation of verbs from fluent speech.

Two experiments sought to extend the demonstration of English-learning infants' abilities to segment nouns from fluent speech to a new lexical class: verbs. Moreover, we explored whether two factors previously shown to influence noun segmentation, stress pattern (strong-weak or weak-strong) and type of initial phoneme (consonant or vowel), also influence verb segmentation. Our results establish the early emergence of verb segmentation in English: by 13.5 months for strong-weak consonant- or vowel-initial verbs and for weak-strong consonant-initial verbs; and by 16.5 months for weak-strong verbs beginning with a vowel. This generalizes previous reports of early segmentation to a new lexical class, thereby providing additional evidence that segmentation is likely to contribute to lexical acquisition. The effects of stress pattern and onset type found are similar to those previously obtained for nouns, in that verbs with a weak-strong stress pattern and verbs beginning with a vowel appear to be at a disadvantage in segmentation. Finally, we present prosodic analyses that suggest a possible effect of prosodic boundary and pitch accent distribution on segmentation. These prosodic differences potentially explain a developmental lag in verb segmentation observed in the present study compared to earlier findings for noun segmentation.

Examination of the Locus of Positional Effects on Children's Production of Plural -s: Considerations From Local and Global Speech Planning.

PURPOSE: Prosodic and articulatory factors influence children's production of inflectional morphemes. For example, plural -s is produced more reliably in utterance-final compared to utterance-medial position (i.e., the positional effect), which has been attributed to the increased planning time in utterance-final position. In previous investigations of plural -s, utterance-medial plurals were followed by a stop consonant (e.g., dogsbark), inducing high articulatory complexity. We examined whether the positional effect would be observed if the utterance-medial context were simplified to a following vowel. METHOD: An elicited imitation task was used to collect productions of plural nouns from 2-year-old children. Nouns were elicited utterance-medially and utterance-finally, with the medial plural followed by either a stressed or an unstressed vowel. Acoustic analysis was used to identify evidence of morpheme production. RESULTS: The positional effect was absent when the morpheme was followed by a vowel (e.g., dogseat). However, it returned when the vowel-initial word contained 2 syllables (e.g., dogsarrive), suggesting that the increased processing load in the latter condition negated the facilitative effect of the easy articulatory context. CONCLUSIONS: Children's productions of grammatical morphemes reflect a rich interaction between emerging levels of linguistic competence, raising considerations for diagnosis and rehabilitation of language disorders.

Timing in talking: what is it used for, and how is it controlled?

In the first part of the paper, we summarize the linguistic factors that shape speech timing patterns, including the prosodic structures which govern them, and suggest that speech timing patterns are used to aid utterance recognition. In the spirit of optimal control theory, we propose that recognition requirements are balanced against requirements such as rate of speech and style, as well as movement costs, to yield (near-)optimal planned surface timing patterns; additional factors may influence the implementation of that plan. In the second part of the paper, we discuss theories of timing control in models of speech production and motor control. We present three types of evidence that support models of speech production that involve extrinsic timing. These include (i) increasing variability with increases in interval duration, (ii) evidence that speakers refer to and plan surface durations, and (iii) independent timing of movement onsets and offsets.

Tapped out: do people with aphasia have rhythm processing deficits?

PURPOSE: In this study, the authors tested whether people with aphasia (PWAs) show an impaired ability to process rhythm, both in terms of perception and production. METHOD: Two experiments were conducted. In Experiment 1, 16 PWAs and 15 age-matched control participants performed 3 rhythm tasks: tapping along to short rhythms, tapping these same rhythms from memory immediately after presentation, and making same-different judgments about pairs of tapped rhythms that they heard. Comparison tasks measured same-different judgment ability with visual stimuli and nonverbal working memory (Corsi blocks). In Experiment 2, 14 PWAs and 16 control participants made same-different judgments for pairs of auditory stimuli that differed in terms of rhythm or pitch (for comparison). RESULTS: In Experiment 1, PWAs performed worse than control participants across most measures of rhythm processing. In contrast, PWAs and control participants did not differ in their performance on the comparison tasks. In Experiment 2, the PWAs performed worse than control participants across all conditions but with a more marked deficit in stimulus pairs that differed in rhythm than in those that differed in pitch. CONCLUSIONS: The results support the hypothesis that at least some PWAs exhibit deficits of rhythm and timing. This may have implications for treatments involving tapping or other rhythmic cues.

Temporal regularity in speech perception: Is regularity beneficial or deleterious?

Speech rhythm has been proposed to be of crucial importance for correct speech perception and language learning. This study investigated the influence of speech rhythm in second language processing. German pseudo-sentences were presented to participants in two conditions: 'naturally regular speech rhythm' and an 'emphasized regular rhythm'. Nine expert English speakers with 3.5±1.6 years of German training repeated each sentence after hearing it once over headphones. Responses were transcribed using the International Phonetic Alphabet and analyzed for the number of correct, false and missing consonants as well as for consonant additions. The over-all number of correct reproductions of consonants did not differ between the two experimental conditions. However, speech rhythmicization significantly affected the serial position curve of correctly reproduced syllables. The results of this pilot study are consistent with the view that speech rhythm is important for speech perception.

Acoustic evidence for positional and complexity effects on children's production of plural -s.

PURPOSE: Some variability in children's early productions of grammatical morphemes reflects phonological factors. For example, production of 3rd person singular -s is increased in utterance-final versus utterance-medial position and in simple versus cluster codas (e.g., sees vs. hits). Understanding the factors that govern such variability is an important step toward modeling developmental processes. In this study, the authors examined the generality of these effects by determining whether position and coda complexity influence production of plural -s, which phonologically manifests the same as 3rd person singular -s. METHOD: The authors used an elicited imitation task to examine the speech of 16 two-year-olds. Eight plural nouns (half contained simple codas, half contained cluster codas) were elicited utterance-medially and utterance-finally. Acoustic analysis of each noun was used to identify acoustic cues associated with coda production. RESULTS: Results showed that plural production was more robust in utterance-final versus utterance-medial position but equally robust in simple versus cluster codas. CONCLUSIONS: These findings extend positional effects on morpheme production to plural -s. An effect of coda complexity was not observed for plural but was observed for 3rd person singular, which raises the possibility that the morphological representation proper influences the degree to which phonological factors affect morpheme production.