Laryngeal Reaction Time Research Articles

Voice target time in Parkinson’s disease: A preliminary report

A target-matching paradigm was developed to assess the vocal equivalents of reaction and movement time in Parkinson’s disease. Six patients with Parkinson’s disease and 6 age- and gender-matched control subjects were asked to enunciate /pa/ to reach a target frequency and intensity level in response to a light stimulus. The stimulus and acoustic responses were simultaneously recorded. Measures included laryngeal reaction time, time between stimulus and phonation onset; frequency voice target time, time from phonation onset to target level of frequency; and amplitude voice target time, time from phonation onset to target level of intensity. The 2 subject groups were significantly differentiated by laryngeal reaction time ( t = –299.67, df = 10, P = 0.005) and frequency voice target time ( t = –148, df = 10, P = 0.014). These data suggest voice target time is a viable tool for assessing the effects of neurologic disorders on voice execution in Parkinson’s disease. (Otolaryngol Head Neck Surg 1999;121:87-91.)

Foreperiod duration, range, and ordering effects on acoustic LRT in normal speakers

One quantitative measure of vocal motor control is phonation onset latency relative to presentation of an external stimulus in a reaction time task. However, variables within the design of reaction time experiments can affect laryngeal reaction time (LRT) values. The present study examines effects of foreperiod characteristics on LRT for normal speakers. Foreperiod is the interval between presentation of warning and response cues. LRT was affected by absolute foreperiod duration, by the average foreperiod duration of a block of trials, and by the ordering and range of foreperiods within a block of trials. Results are discussed with respect to foreperiod effects on the subjective expectancy and objective probability of occurrence of the response cue and on the timing of neurophysiologic processes. Control of subjective effects is critical to assessment of neurophysiologic constraints on LRT.

Foreperiod effects on acoustic laryngeal reaction time

In a simple reaction time task, foreperiod is the preparatory interval between presentation of a warning cue and a respond cue. Two studies examined effects of foreperiod duration, range, and distribution on laryngeal reaction time (LRT) values for production of the isolated vowel /a/. The first study examined foreperiods presented in two series with different durations and ranges (200–1000 ms and 700–2300 ms). Each series had a rectangular distribution. The second study examined the same two foreperiod series presented in nonaging (equi-probable) distributions. Variable inter-stimulus intervals and subject instructions inhibited initiation of preparation prior to presentation of the warning cue. Laryngeal reaction time (LRT) values decreased as foreperiod increased in each series. LRT was longest after the shortest foreperiod in a series, regardless of its absolute length. The same absolute duration foreperiod (i.e., 700–1000 ms) yielded a longer LRT when it was embedded in a wider range of foreperiods. The quadratic relation between foreperiod duration and LRT [K. Izdebski, J. Speech Hear. Res. 23, 485–489 (1978)] was more pronounced when a series was presented as a nonaging distribution versus a rectangular distribution.

Brain blood flow related to acoustic laryngeal reaction time in adult developmental stutterers.

The 1980s witnessed renewed interest in the relation between developmental stuttering and central nervous system (CNS) abnormalities. We have reported differences between nonstutterers and developmental stutterers on electrophysiologic (QTE) and metabolic (rCBF) measures of brain function. A critical step in the interpretation of results of functional brain imaging studies is to determine the relation, if any, of identified CNS abnormalities to speech motor control in persons who stutter. In this study we addressed the interpretation of rCBF findings by asking whether we could identify patterns of impaired acoustic laryngeal reaction time (LRT) as a function of response complexity parallel to rCBF findings. Stutterer subgroups determined by clinical severity ratings were not differentiated by LRT values as a function of response complexity. Stutterers with relative blood flow asymmetry below the normal median value involving both left superior and middle temporal regions of interest (ROIs) showed significantly longer LRT for the complex response than did normal speakers and stutterers with above-normal median relative flow values to at least one of these temporal ROIs. Stutterer subgroups based on reduced cingulate flow alone were not differentiated by LRT values. Findings are consistent with Goldberg's (1985) model of CNS premotor processing. Findings also suggest that stutterer subgroups might be distinguished by the presence, loci, and relative magnitude of cortical and/or subcortical rCBF abnormality in regions that subserve a fluency-generating system.

Representing laryngeal reaction time performance

Summary Different calculation methods have been used to derive laryngeal reaction time (LRT) values. Some represent average LRT performance and others, optimal. Whether experimental outcome differed depending on choice of calculation method was tested. Outcome included absolute LRT values, subjects' relative performance, and relationships between LRT values and other variables. Six calculation methods (two representing average performance, two representing optimal, and two others) were selected. Overall, outcome did not differ between the two calculation methods representing optimal performance, nor between the two representing average performance. However, outcome could differ between methods representing optimal and average performance. These results suggest that calculating an optimal and an average measure, or using a measure capturing aspects of both would be useful, especially when studying pathological populations. The difference between a given subject's average and optimal performance may also reveal additional information

Laryngeal Reaction Time Profiles in Spasmodic Dysphonia

This study combines measures of linguistic and vocal performance and long-latency auditory electrophysiology to investigate task-dependent variability in spasmodic dysphonia (SD). Linguistic performance was evaluated using several measures of relatively complex linguistic ability (i.e., discourse analysis). Vocal performance was evaluated by measuring acoustic laryngeal reaction time (LRT) for tasks that differ in complexity. Normal structure of the cortex and subcortex was confirmed by magnetic resonance imaging. Cortical function was measured using multichannel quantitative auditory evoked potentials (AEPs). As a group, SD subjects who demonstrated subtle linguistic deficits also demonstrated prolonged LRT for the complex task and repeated and persistent auditory electrophysiologic abnormalities over the anterior quadrant of the left hemisphere. As a group, linguistically normal SD subjects demonstrated no significant increase in LRT for the complex task and no recurrent electrophysiologic abnormalities over the left anterior cortex relative to normal controls. Results support a neurogenic origin of SD and suggest that some aspects of inter- and intrasubject variability may be related to differences in loci and magnitude of cortical abnormalities.

Preparation Time and Response Complexity Effects on Stutterers’ and Nonstutterers’ Acoustic LRT

Nonstutterers', mild stutterers', and severe stutterers' acoustic laryngeal reaction times (LRTs) were recorded for isolated vowels and nonpropositional VCV responses in different stimulus conditions governing response preparation. In all stimulus-response conditions severe stutterers produced the longest LRTs, followed in turn by mild stutterers and nonstutterers. The three groups significantly differed from one another in most conditions, but the magnitude of difference between mild and severe stutterers was notably greater than the difference between mild stutterers and nonstutterers. LRT changes as a function of stimulus condition showed that, in general, nonstutterers were best able to use a preparation-facilitating stimulus condition to reduce LRT, and severe stutterers least able to do so. LRT changes as a function of response complexity showed that only nonstutterers produced statistically significant within-group differences. Patterns of LRT change as a combined function of group, stimulus condition, and response type suggest a complex relationship between stutterer severity, preparation time, and type of response complexity. Results illustrate aspects of Goldberg's (1985) model of preparation processes, and support hypotheses that stutterer subgroups show differential preparation deficits along with high motor initiation variability.

Respiratory/laryngeal coupling and complexity effects on acoustic laryngeal reaction time in normal speakers

<h2>Summary</h2> The simple reaction time paradigm was used to investigate effects of peripheral (respiratory/laryngeal coupling) and central (task complexity) requirements on average acoustic laryngeal reaction time (LRT) values in normal speakers. Respiratory/laryngeal coupling at response onset varied from glottal stop to aspirate. Complexity varied from isolated vowel to short sentence. The range from shortest to longest average LRT value across all tasks was 69 ms. Significant differences among tasks indicate that acoustic LRT values are sensitive to relatively small magnitude effects associated with respiratory/laryngeal coupling and task complexity. Results led to formulation of two hypotheses, which, while consistent with present findings, require further investigation: First, LRT increases directly with increasing glottal resistance. Second, LRT increases directly with increases in the number of stressed syllables in the response.

Linguistic performance deficits in stutterers: Relation to laryngeal reaction time profiles

Converging evidence suggests that stuttering is associated with deficits in the planning and execution of speech. Evidence also suggests that the onset, development, and loci of stuttering are related to demands language places on speech motor planning and execution. We combined linguistic and vocal motor assessments to address two questions: 1) Can we identify a subgroup of adult stutterers who demonstrate linguistic deficits? and 2) Do linguistically normal and impaired stutterers show different patterns of laryngeal reaction time (LRT) as a function of response complexity? Linguistic performance was evaluated using tasks that assess relatively high-level production and comprehension processes. Responses used to record LRT differed in linguistic and motoric complexity. Only linguistically impaired stutterers showed significant increases in LRT for complex responses. Findings suggest that linguistic and motor processes affect the efficiency and fluency of speech motor control and that both processes be made explicit in models of stuttering.

Relationships Between Selected Auditory and Phonatory Latency Measures in Normal Speakers

Interaction between auditory and phonatory systems was explored in normal speakers by comparing laryngeal reaction time (LRT) with interpeak intervals from the auditory brainstem response (ABR) obtained using high and low stimulus presentation rates. Thirty-four subjects with no history of neurological or speech-language disorders and normal hearing sensitivity participated. Interpeak intervals were derived from ABR's recorded for each ear at rates of 21.1 and 91.1 clicks/s. LRT responses were obtained by instructing subjects to sustain an /s/ and then phonate an /a/ as fast as possible following visual cues. Two measures of reaction time performance were derived, Mean Laryngeal Reaction Time (MLRT) and Best Laryngeal Reaction Time (BLRT). Linear regression analyses were completed between each measure of reaction time performance and each ABR interpeak interval. Using either LRT measure, two significant (p less than .05) positive linear relationships were found. One involved the interpeak interval between Waves III and V and the other involved the interpeak interval between Waves I and V. Both were recorded at high stimulus presentation rates. These results support the small body of literature from normal speakers, stutterers, and spasmodic dysphonics suggesting interaction between the auditory and phonatory systems at the brainstem level.

A comparative investigation of the laryngeal premotor, adjustment, and reaction times of stutterers and nonstutterers.

The laryngeal premotor, adjustment, and reaction times of 24 stutterers and 24 nonstutterers were assessed by means of a group (2) by stimulus modality (3) by stimulus order (6) factorial investigation. The laryngeal measures were determined from print outs made from electroglottographic recordings taken during the production of [a] that was cued by a visual, auditory, or somato-sensory stimulus. The results revealed that the laryngeal reaction times of stutterers were significantly longer than those of the nonstutterers. Moreover, the reaction times were significantly longer both during the laryngeal premotor and adjustment time periods. The observed between-group difference for each of these laryngeal measures was independent of the stimulus that was employed.

Physiological bases of acoustic LRT in nonstutterers, mild stutterers, and severe stutterers.

The simple reaction time paradigm, incorporating a variable foreperiod, was used to investigate relative contributions of the respiratory and laryngeal systems to mild and severe stutterers' prolonged acoustic laryngeal reaction time (LRT) values. Prephonatory kinematic data were analyzed in terms of frequency of initiation, timing, and organization of events executed to attain the functional physiological targets of respiratory inflation during foreperiods and phonation onset after foreperiods. Acoustic data replicated a previously observed composite stuttering severity and foreperiod effect on stutterers' acoustic LRT values. Kinematic data revealed that, in general, the mild stutterers demonstrated delayed initiation of respiratory events and appropriate organization of respiratory and laryngeal events while the severe stutterers demonstrated delayed initiation of laryngeal events and inappropriate organization of respiratory and laryngeal events. That is, kinematic data both account for group differences in acoustic LRT values as a function of foreperiod and support the notion that differential respiratory and laryngeal deficits underly mild and severe stutterers' prolonged acoustic LRT values.

Organization and timing of prephonatory movements in mild and severe stutterers

In a previous paper [J. Acoust. Soc. Am. Suppl. 1 73, S16 (1983)], we reported a composite foreperiod and stuttering severity effect on stutterers' acoustic laryngeal reaction time (LRT) values. That is, mild, but not severe, stutterers' LRT values approach nonstutterers' values as foreperiod increases. This observation lead to the formulation of the differential deficit hypothesis, which suggests that mild and severe stutterers execute qualitatively different prephonatory movements. In the study reported here, the differential deficit hypothesis was tested directly by examining movement and acoustic data obtained simultaneously from mild and severe stutterers and nonstutterers. The acoustic data replicated our previous results with respect to the composite foreperiod and stuttering severity effect on stutterers' LRT values. More importantly, movement data reveal that mild and severe stutterers can be differentiated on the basis of the organization, frequency of occurrence, and timing of prephonatory laryngeal and respiratory movements. That is, movement data both support the differential deficit hypothesis and account for the composite foreperiod and stuttering severity effect on stutterers' acoustic LRT values. [Work supported by NINCDS grant NS 13870 to Haskins Laboratories.]

Foreperiod and stuttering severity effects on acoustic laryngeal reaction time

An earlier paper presented a model of the laryngeal reaction time (LRT) paradigm that included several factors that appeared to affect LRT values. The present study assesses the effects of two of these factors: foreperiod and stuttering severity. The former was assessed by the use of 13 foreperiod durations. The latter was assessed by classifying experimental subjects as either mild or severe stutterers. Both factors significantly affected LRT values. More importantly, these factors demonstrated a composite effect on group LRT differences. Specifically, mild stutterers' LRT values approached normal values as foreperiod increased, whereas severe stutterers' LRT values remained significantly greater than normal values at all foreperiods. Results are discussed in terms of differential posturing and/or vibration initiation deficits underlying stutterers' delayed LRT values. We caution that acoustic measurements alone are insufficient to specify fully the nature of the underlying deficits.

A comparison of LRT and VOT values between stutterers and nonstutterers

The experiment reported here found no significant group differences in laryngeal reaction time (LRT) and voice onset time (VOT) values. Rank-order correlations between the stutterers' LRT and VOT values were also nonsignificant. A model of the LRT paradigm is presented that (1) allows for systematic assessment of factors possibly contributing to the failure to replicate the often reported LRT group difference, and (2) is useful in examining the relationship between the LRT experimental condition and normal speaking conditions. We argue that two factors were particularly critical to our results. First, simple reaction time procedures included (1) a warning signal that preceded a response signal by a variable 1–3-sec foreperiod, and (2) a single response. We argue that foreperiod durations exceeded the stutterers' speech posture time for a known response. Second, the stuttering severity rating of our experimental group was less severe than ratings in other experiments.