Kaitlin L. Lansford

The use of fundamental frequency for lexical segmentation in listeners with cochlear implants

Fundamental frequency (F0) variation is one of a number of acoustic cues normal hearing listeners use for guiding lexical segmentation of degraded speech. This study examined whether F0 contour facilitates lexical segmentation by listeners fitted with cochlear implants (CIs). Lexical boundary error patterns elicited under unaltered and flattened F0 conditions were compared across three groups: listeners with conventional CI, listeners with CI and preserved low-frequency acoustic hearing, and normal hearing listeners subjected to CI simulations. Results indicate that all groups attended to syllabic stress cues to guide lexical segmentation, and that F0 contours facilitated performance for listeners with low-frequency hearing.

A Cognitive-Perceptual Approach to Conceptualizing Speech Intelligibility Deficits and Remediation Practice in Hypokinetic Dysarthria

Hypokinetic dysarthria is a common manifestation of Parkinsons disease, which negatively influences quality of life. Behavioral techniques that aim to improve speech intelligibility constitute the bulk of intervention strategies for this population, as the dysarthria does not often respond vigorously to medical interventions. Although several case and group studies generally support the efficacy of behavioral treatment, much work remains to establish a rigorous evidence base. This absence of definitive research leaves both the speech-language pathologist and referring physician with the task of determining the feasibility and nature of therapy for intelligibility remediation in PD. The purpose of this paper is to introduce a novel framework for medical practitioners in which to conceptualize and justify potential targets for speech remediation. The most commonly targeted deficits (e.g., speaking rate and vocal loudness) can be supported by this approach, as well as underutilized and novel treatment targets that aim at the listeners perceptual skills.

Crosslinguistic Application of English-Centric Rhythm Descriptors in Motor Speech Disorders

Background: Rhythmic disturbances are a hallmark of motor speech disorders, in which the motor control deficits interfere with the outward flow of speech and by extension speech understanding. As the functions of rhythm are language-specific, breakdowns in rhythm should have language-specific consequences for communication. Objective: The goals of this paper are to (i) provide a review of the cognitive-linguistic role of rhythm in speech perception in a general sense and crosslinguistically; (ii) present new results of lexical segmentation challenges posed by different types of dysarthria in American English, and (iii) offer a framework for crosslinguistic considerations for speech rhythm disturbances in the diagnosis and treatment of communication disorders associated with motor speech disorders. Summary: This review presents theoretical and empirical reasons for considering speech rhythm as a critical component of communication deficits in motor speech disorders, and addresses the need for crosslinguistic research to explore language-universal versus language-specific aspects of motor speech disorders.

Use of Crowdsourcing to Assess the Ecological Validity of Perceptual-Training Paradigms in Dysarthria

PURPOSE It has been documented in laboratory settings that familiarizing listeners with dysarthric speech improves intelligibility of that speech. If these findings can be replicated in real-world settings, the ability to improve communicative function by focusing on communication partners has major implications for extending clinical practice in dysarthria rehabilitation. An important step toward development of a listener-targeted treatment approach requires establishment of its ecological validity. To this end, the present study leveraged the mechanism of crowdsourcing to determine whether perceptual-training benefits achieved by listeners in the laboratory could be elicited in an at-home computer-based scenario. METHOD Perceptual-training data (i.e., intelligibility scores from a posttraining transcription task) were collected from listeners in 2 settings-the laboratory and the crowdsourcing website Amazon Mechanical Turk. RESULTS Consistent with previous findings, results revealed a main effect of training condition (training vs. control) on intelligibility scores. There was, however, no effect of training setting (Mechanical Turk vs. laboratory). Thus, the perceptual benefit achieved via Mechanical Turk was comparable to that achieved in the laboratory. CONCLUSION This study provides evidence regarding the ecological validity of perceptual-training paradigms designed to improve intelligibility of dysarthric speech, thereby supporting their continued advancement as a listener-targeted treatment option.

Rhythm Perception and Its Role in Perception and Learning of Dysrhythmic Speech.

Purpose The perception of rhythm cues plays an important role in recognizing spoken language, especially in adverse listening conditions. Indeed, this has been shown to hold true even when the rhythm cues themselves are dysrhythmic. This study investigates whether expertise in rhythm perception provides a processing advantage for perception (initial intelligibility) and learning (intelligibility improvement) of naturally dysrhythmic speech, dysarthria. Method Fifty young adults with typical hearing participated in 3 key tests, including a rhythm perception test, a receptive vocabulary test, and a speech perception and learning test, with standard pretest, familiarization, and posttest phases. Initial intelligibility scores were calculated as the proportion of correct pretest words, while intelligibility improvement scores were calculated by subtracting this proportion from the proportion of correct posttest words. Results Rhythm perception scores predicted intelligibility improvement scores but not initial intelligibility. On the other hand, receptive vocabulary scores predicted initial intelligibility scores but not intelligibility improvement. Conclusions Expertise in rhythm perception appears to provide an advantage for processing dysrhythmic speech, but a familiarization experience is required for the advantage to be realized. Findings are discussed in relation to the role of rhythm in speech processing and shed light on processing models that consider the consequence of rhythm abnormalities in dysarthria.

Quantifying speech rhythm deficits in dysarthria

Disturbances in speech rhythm are common in dysarthria, and deficit patterns vary among dysarthria subtypes. Attempts to quantify differences in disordered rhythm patterns have met with limited success. Here, we attempt to differentiate various forms of dysarthria using metrics designed to quantify linguistic rhythm on a stress‐timed versus syllable‐timed continuum. Speakers with hypokinetic, ataxic, hyperkinetic, or mixed flaccid‐spastic dysarthria read sentences. Rhythm metrics were calculated for these utterances based on vocalic and consonantal interval durations. Differences among groups were discovered for %V (percentage of utterance duration comprised of vocalic intervals), VarcoV (rate‐normalized standard deviation of vocalic interval durations), and nPVI‐V (normalized pairwise variability index for vocalic intervals). Differences were independent of variable speaking rates among groups. All dysarthric groups produced rhythm patterns less stress‐timed than the control American English speakers, wi...

Stable production rhythms across languages for bilingual speakers.

There has been a great deal of work on classifying spoken languages according to their perceived or acoustically‐measured rhythmic structures. The current study examined the speech of 12 Spanish‐English bilinguals producing sentences in both languages using rhythmic measures based on the amplitude envelopes extracted from different frequency regions—the envelope modulation spectrum (EMS). Using discriminant factor analysis, EMS variables demonstrated a moderate ability to classify the language being spoken suggesting that rhythmic differences between languages survive even when speaker is controlled. More interesting is the fact that EMS variables could reliably classify which speaker produced each sentence even across languages. This result suggests that there are stable rhythmic structures in an individual talker’s speech that are apparent above and beyond the structural constraints of the language spoken. The EMS appears capable of describing systematic characteristics of both the talker and the langua...

Discriminating language and talker using non-linguistic measures of rhythm, spectral energy and f0

Recent studies have shown that rhythm metrics calculated from amplitude envelopes extracted from octave bands across the spectrum (the envelope modulation spectrum or EMS) can reliably discriminate between spoken Spanish and English even when produced by the same speakers [Carbonell et al., J. Acoust. Soc. Am. 129, 2680]. Additionally, bilingual speakers could be discriminated fairly seven females and five males well on EMS variables even across sentences spoken in the different languages. In the current study, EMS, a general acoustic measure with no reference to phoneme/linguistic entities, was supplemented with measures of the mean and variance of spectral energy in each octave band as well as the mean and variance of fundamental frequency. Using stepwise discriminant analysis and the set of bilingual productions of Spanish and English, it was determined that language discrimination was excellent using both EMS and spectral measures, whereas spectral and f0 measures were most informative for speaker dis...

Word recognition in dysarthric speech: Evidence for the time‐course hypothesis

The detrimental effect of speaker variability on word recognition has been reported using a wide variety of tasks and stimuli. In this study, the use of dysarthric speech alongside unimpaired speech allowed us to examine the effect of indexical variability from a new perspective. We compared voice‐specificity effects in words produced by healthy speakers and the same words produced by dysarthric patients suffering from Huntington’s disease (HD). The speech of persons with HD is particularly suited to this issue because of its idiosyncratic and variable manifestation. Reaction time and accuracy results provided confirmatory evidence for Luce et al.’s (2003) time‐course hypothesis: The slower responses occasioned by processing dysarthric stimuli were accompanied with greater reliance on surface details of the stimuli. Thus, specificity effects can be seen as resulting from a coping strategy called upon when the system is presented with an input that is highly dissimilar from canonical lexical representation...

The role of rhythm in adaptation to dysrhythmic speech, continued

Rhythm cues have been shown to be important for deciphering speech in adverse listening conditions, even when the rhythm cues are corrupted. In an initial attempt to document the relationship between rhythm perception and processing of a naturally dysrhythmic speech signal, we found that listeners with expertise in rhythm perception were not advantaged with initial intelligibility of ataxic dysarthria but were significantly advantaged with adaptation to the degraded speech signal [Borrie, Lansford, and Barrett, Journal of Speech, Language, and Hearing Research, 60, 561–570 (2017)]. We speculated that listeners with skills in rhythm perception are better able to exploit experience (familiarization) with the degraded speech, learning something useful about corrupted rhythm cues for subsequent processing. This current study investigated whether the relationship between rhythm perception and perceptual adaptation of dysrhythmic speech, observed in our previous study with ataxic dysarthria, holds for other forms of dysrhythmic speech. Here, we replicate our original study with two different forms of dysarthria: the largely irregular and unpredictable speech of hyperkinetic dysarthria secondary to Huntington’s disease, and the relatively regular and predictable speech of hypokinetic dysarthric speech secondary to Parkinson’s disease. Results will bear on models of dysrhythmic speech perception as well as clinical practice.Rhythm cues have been shown to be important for deciphering speech in adverse listening conditions, even when the rhythm cues are corrupted. In an initial attempt to document the relationship between rhythm perception and processing of a naturally dysrhythmic speech signal, we found that listeners with expertise in rhythm perception were not advantaged with initial intelligibility of ataxic dysarthria but were significantly advantaged with adaptation to the degraded speech signal [Borrie, Lansford, and Barrett, Journal of Speech, Language, and Hearing Research, 60, 561–570 (2017)]. We speculated that listeners with skills in rhythm perception are better able to exploit experience (familiarization) with the degraded speech, learning something useful about corrupted rhythm cues for subsequent processing. This current study investigated whether the relationship between rhythm perception and perceptual adaptation of dysrhythmic speech, observed in our previous study with ataxic dysarthria, holds for other fo...