Effects of listener uncertainty on articulatory inconsistency

This investigation determined the effects of listener uncertainty on articulatory inconsistency. Subjects were 15 children between three and five years of age. Each subject was tested to find a set of 45 pictures to which articulatory responses would contain sound errors on: /f,v,th,s,ts,dz/. After one week, articulatory responses to these 45 stimuli elicited by traditional picture naming techniques were compared to productions of the same words elicited in an experimental communication setting. The number of sound errors decreased significantly (p less than or equal to 0.01) in the experimental communication setting when the listener pretended to be uncertain of what the speaker said. This finding was interpreted to mean that listener uncertainty may increase the effectiveness of articulatory remediation procedures if included in treatment programs.     

A preliminary study of factors influencing perception of articulatory rate in Parkinson disease.

This investigation was a preliminary study of factors influencing perception of articulatory rate in idiopathic Parkinson disease (PD). Nine men with mild to moderate idiopathic PD and 9 healthy men of a similar age read the Farm Passage at habitual, fast, and slow reading rates. Spontaneous speech samples also were obtained. Speech severity for participants with PD was mild to moderate; prominent perceptual characteristics further suggested hypokinetic dysarthria. Nine listeners estimated the articulatory rate of speech runs (i.e., stretch of speech bounded by pauses) extracted from the reading and spontaneous speech samples. Regression analysis was used to explore the relationship between articulatory rate (i.e., syllables produced per second excluding pauses) and perceptual impressions of articulatory rate as well as the relationship between fundamental frequency (F0) range and perceptual estimates of articulatory rate. Regression functions predicting perceptual estimates of articulatory rate from F0 range were not significant for either speaker group. The regression analyses relating articulatory rate and perceptual estimates of articulatory rate, however, revealed a significant, positive relationship between the two measures for both speaker groups. There also was a nonsignificant trend for perception of articulatory rate to grow more rapidly for Parkinsonian speech samples. Although the current findings should be interpreted with caution until they have been validated by additional studies using much larger speaker populations and more extensive speech samples, the results hint at the possibility that perceptual impressions of articulatory rate in PD may overestimate the actual, physical rate. The results also highlight the importance of speech-language pathologists complimenting perceptual judgements of articulatory rate with physical measures.     

The use of main concept analysis to measure discourse production in Cantonese-speaking persons with aphasia: A preliminary report

Discourse produced by speakers with aphasia contains rich and valuable information for researchers to understand the manifestation of aphasia as well as for clinicians to plan specific treatment components for their clients. Various approaches to investigate aphasic discourse have been proposed in the English literature. However, this is not the case in Chinese. As a result, clinical evaluations of aphasic discourse have not been a common practice. This problem is further compounded by the lack of validated stimuli that are culturally appropriate for language elicitation. The purpose of this study was twofold: (a) to develop and validate four sequential pictorial stimuli for elicitation of language samples in Cantonese speakers with aphasia, and (b) to investigate the use of a main concept measurement, a clinically oriented quantitative system, to analyze the elicited language samples. Twenty speakers with aphasia and ten normal speakers were invited to participate in this study. The aphasic group produced significantly less key information than the normal group. More importantly, a strong relationship was also found between aphasia severity and production of main concepts. While the results of the inter-rater and intra-rater reliability suggested the scoring system to be reliable, the test–retest results yielded strong and significant correlations across two testing sessions one to three weeks apart.Learning outcomes: Readers will demonstrate better understanding of (1) the development and validation of newly devised sequential pictorial stimuli to elicit oral language production, and (2) the use of a main concept measurement to quantify aphasic connected speech in Cantonese Chinese.     

Computerized Two-Dimensional Model for Finnish Vowel Identifications'

511 different vowel-like stimuli were produced using a computer and speech synthesizer OVE III B. Their first formant varied from 250 to 800 Hz and their second formant from 800 to 2 400 Hz, covering thus the formant frequencies of the eight Finnish vowels. The randomized stimuli were listened to by 32 young adults with normal hearing. The identifications were analyzed automatically with the computer and plotted on a two-dimensional plane as a function of F₁ and F². The resulting basic vowel identification chart demonstrates the areas where the stimuli were identified as a certain vowel. The chart offers the practical means for presentation and follow-up of individual articulatory and auditory capacities.     

Methodological variables affecting phonational frequency range in adults

This study examined the effects of selected elicitation variables on phonational frequency (Fo) range in normal adults. Twenty men and 20 women responded to five audiotaped tone conditions: (a) discrete steps, (b) slow steps, (c) fast steps, (d) slow glissando, and (e) fast glissando. These stimuli were devised to elicit each person's maximal and minimal Fo. All elicitation conditions evoked a significantly higher maximal Fo and a significantly larger Fo range (in both hertz and semitones) than did the discrete-steps condition. Fast steps produced a significantly higher minimal Fo than did fast glissando. Both slow glissando and fast glissando yielded a significantly larger Fo range in semitones than did fast steps. Finally, the women demonstrated a significantly larger Fo range (in hertz but not semitones) than did the men.     

CIU and main event analyses of the structured discourse of older and younger adults

Correct information unit (CIU) and main event analyses are quantitative measures for analyzing discourse of individuals with aphasia. Comparative data from healthy younger (YG) and older (OD) adults and an investigation of the influence of stimuli type would considerably extend the usefulness of such analyses. The objectives were (a) to compare discourse ability of younger and older healthy adults, and (b) to investigate influence of stimuli type on performance. Seventeen younger and 17 older healthy adults participated. Language samples obtained were analyzed for CIU and proportion of main events. Results indicated the YG group produced more accurate, relevant, and informative content than the OD group, and participants expressed more main events in response to sequential picture stimuli, regardless of age. We conclude that clinicians should consider stimuli type when measuring discourse ability. Age should also be considered when comparing performance of adults with brain damage to that of healthy adults.

Learning outcomes:

The reader will be able to: (a) recognize the importance of obtaining information about discourse performance in both older and younger healthy adults; (b) identify the purposes of CIU analysis and main event analysis for examining discourse; and (c) appreciate the potential influences of different language elicitation procedures on the discourse obtained from a task.     

Optimal stimulus intensity and reliability of air stimulation technique for elicitation of laryngo-upper esophageal sphincter contractile reflex

To determine the optimal air stimulus intensity and duration for elicitation of the laryngo-upper esophageal sphincter (UES) contractile reflex, we studied 37 healthy volunteers 20 to 81 years of age. A sleeve device monitored the UES pressure. For laryngeal stimulation, we used an air stimulator unit (Pentax AP-4000) that incorporated a nasolaryngeal endoscope. The arytenoids and interarytenoid areas were stimulated at least three times by three different stimuli: 6-mm Hg air pulse with 50-ms duration, 10-mm Hg air pulse with 50-ms duration, and 6-mm Hg air pulse with 2-second duration. Of 1,165 air stimulations, 1,041 resulted in mucosal deflections. Of these, 451 resulted in an abrupt increase in UES pressure. The response/deflection ratio for 6-mm Hg stimulation with 2-second duration was significantly higher than those for air pulses with 50-ms duration (p < .001). We conclude that although the laryngo-UES contractile reflex can be elicited by an air pulse with 50-ms duration, this ultrashort stimulation is not reliable. Using longer-duration pulses (at least 2 seconds) improves the reliability of elicitation of the laryngo-UES contractile reflex.     

Acoustic tracking of articulation errors: [r]

The objective of this study was to determine the usefulness of acoustic tracking as a supplement to perceptual judgements during remediation. One child, receiving weekly individual treatment, participated in a drill-and-practice approach to remediation for a single [w]-for-/r/ substitution error. Imitations of consonant-vowel (CV), VCV, and matched /r/ and /w/ sentence stimuli were audiotape recorded. The temporal and spectral characteristics of the recorded stimuli (i.e., the F2 transition rates and F2 values for the changing [r]) were spectrographically tracked and analyzed over a 70-day remediative period. The acoustic data were compared with the perceptual judgments of articulatory change. Generally, as the child's productions moved from the [w] toward the [r], the measured F2 values became higher and the F2 transition rates lowered. Results suggest that acoustic tracking of a child's productions may become a useful tool to augment perceptual tracking. Implications are discussed for the applications of acoustic tracking within clinical practice.     

Concurrent measurement of the detectability of tone bursts and their effect on the excitability of the human blink reflex using a probe-signal method

The probe-signal method has shown that auditory signals that are either presented more often in a series of trials or that are immediately preceded by cues of the same frequency on a single trial are detected more readily than signals of other frequencies. The frequency range in which detection is favored defines an attentional band, which is thought to result from an effective attenuation of deviant frequencies in the cochlea, possibly by activation of the olivocochlear bundle. In a 2IFC procedure in which the first observation interval was preceded by a 1300-Hz cue, subjects detected cued probe tones (at 1300 Hz) but not uncued probe tones (at 1000 Hz or 1600 Hz) at better than chance levels. Concurrent elicitation of a blink reflex by presentation of an air puff in the first observation interval on a random half of the trials showed that cued probes, but not uncued probes, inhibited the size of the blink reflex. These data show that uncued probes do not enter into the low-level sensory processing in the brainstem which is responsible for reflex modification. This finding is consistent with the view that stimuli whose frequency falls outside an attentional band are excluded at the auditory periphery.     

Factors influencing fundamental frequency range estimates in children

Selected elicitation conditions were manipulated to determine their effect on fundamental frequency (Fo) range estimates in children. Forty normal children each responded to five autiotaped tone conditions: (a) discrete steps, (b) slow steps, (c) fast steps, (d) slow glissando, and (e) fast glissando. These tonal stimuli were devised to elicit each child's maximal and minimal Fo. The traditional discrete-steps condition was associated with a lower maximal Fo, higher minimal Fo, and a more restricted Fo range than all other conditions.     

Articulatory changes with short-term deactivation of the cochlear implants of two prelingually deafened children

OBJECTIVE: The purpose of this investigation was to determine how suddenly diminished auditory feedback affects articulatory behaviors for prelingually deafened children with cochlear implants (CIs). DESIGN: Two 6-yr-old children served as participants. Considering their level of hearing impairment, one child had above average speech perception and production skills while the other child had exceptionally good speech perception and production abilities. Baseline data were collected four times over the course of 2 days with the children wearing their CIs. For three additional days, data were collected while the children wore their CIs (ON condition) and then again after their CIs had been deactivated for 1 hr (OFF condition). Variables assessed included amount of jaw opening, F1, F2, nasal air flow, voice onset time (VOT), voicing duration, and the magnitude and duration of intraoral air pressure (Po). Findings were related to each other and to previously reported phonatory findings from the same two children (Higgins, McCleary, & Schulte, 1999) to determine whether changes in articulatory variables in the OFF condition were consistent with a direct effect of diminished auditory feedback or an indirect influence of suprasegmental parameters. RESULTS: Both children exhibited consistent and significant changes in articulatory parameters in the absence of auditory feedback. Such changes occurred more often for the child who had especially proficient speech perception and production skills. Some changes (i.e., reduced Po for [p] and reduced nasal air flow for [m]) appeared related to the influence of suprasegmental parameters, in particular, reduced subglottal air pressure. Other effects (i.e., increased F2 for [a] and reduced VOT for [p]) were suggestive of changes in the children's abilities to maintain appropriate articulatory placements and timing. Finally, a few changes (reduced jaw opening for [i] and increased Po duration for [p]) may have reflected compensatory strategies to maintain correct tongue placement and enhance temporal distinctions in the absence of auditory feedback. CONCLUSIONS: Based on the data of our two participants, it appears that some prelingually deafened children with CIs and good speech perception/production skills rely on auditory feedback to maintain articulatory precision. In the absence of auditory feedback, such children may demonstrate changes in articulatory placement and timing. In addition, data from one of our participants are consistent with the idea that some children may be aware that their articulatory control is compromised in the absence of auditory feedback and attempt to compensate by altering articulatory durations or the range of associated articulatory movements.     

Phonological priming in picture naming of young children who stutter.

The purpose of this study was to assess the influence of phonological priming on the speech reaction time (SRT) of children who do (CWS) and who do not (CWNS) stutter during a picture-naming task. Participants were eighteen 3-5-year-old CWS (M = 50.67 months, SD = 11.83 months), matched in age and gender with 18 CWNS (M = 49.44 months, SD = 10.22 months). The picture-naming task required each child to name, one at a time, computer-presented, white-on-black line drawings of common, age-appropriate objects "as quickly as you can" during 3 different conditions: (a) no prime, (b) related prime, and (c) unrelated prime, with naming latency (alternatively referred to as SRT; in milliseconds) as the main dependent variable. Results indicated that all children exhibited faster or shorter SRTs during the related condition compared to the no prime condition. Similarly, SRT was influenced with advancing age for all children, with 5-year-olds exhibiting faster SRTs than 3-year-olds. Furthermore, CWNS, but not CWS, demonstrated a negative correlation between articulatory mastery and SRT. Findings were taken to suggest that phonological priming is a feasible procedure for studying the speech-language planning and production of 3-5-year-old children and that preschool children who stutter, as a group, may have somewhat less well developed articulatory systems than preschool children who do not stutter.     

Speech modification by a deaf child through dynamic orometric modeling and feedback

Baseline physiologic, acoustic, and phonetic data are presented to characterize speech production of a 3 1/2-year-old deaf girl prior to a visual articulatory modeling and feedback program. These observations suggest that she used an articulatory strategy based on visual information about lip and jaw movements rather than tongue positions as a primary means of differentiating speech sounds. The training program which followed used instrumentally generated displays of tongue position and movements to teach production of the (i) and (a) vowels in single and bisyllable word contexts. Linguapalatal contact patterns for the consonant (t) were then introduced and taught in combinations with the vowels. Goal articulatory gestures were learned rapidly with respect to both positional and timing features of speech.     

Articulatory disorders in speech among Finnish-speaking students according to age, sex, and speech therapy

A group of Finnish-speaking students (n = 451) was examined clinically to study occurrence of articulatory disorders in speech, controlling for the possible effects of age, sex, and previous speech therapy. Distortions of the /s/ sound were found in 16%, of the /r/ sound in 3%, and of the /l/, /n/, or /d/ sounds in about 1% of the subjects; the rarest faultily produced sounds were usually combined with other articulatory disorders. According to fitted log-linear functions, age and sex were not related to prevalence of articulatory disorders in speech among young adults, while there was a tendency for subjects with previous speech therapy to have higher frequencies of articulatory disorders of /s/ and /r/ sounds than subjects with no such treatment, suggesting that exclusion of the treated subjects would have resulted in too low a prevalence of articulatory disorders in the sample.     

Subjective evaluation of articulatory effort

Thirty-two adult speakers repeated pairs of CV syllables, each embedded in a carrier phrase, and designated the consonant member of the pair they believed required more articulatory effort. The task was performed under three speaking conditions (1) normal conversational speech, (2) whispered speech, and (3) pantomimed speech. Voicing and fricative manner of production appeared to be related to judgments of greater articulatory effort. Highly consistent responses across the three speaking conditions suggest other psychological factors to which subjects respond during conditions of normal as well as subvocal modes of speaking. Analyses yielded significant correlations between articulatory effort responses and current data concerning children's phonological acquisition, children's phoneme substitution patterns, and frequency of occurrence of consonants in conversational English.     

Electropalatography in the treatment of articulation/phonological disorders

Treatment using electropalatography (EPG) is described. Speech learners wear a custommade appliance called a pseudopalate in order to view their tongue-to-palate (lingual palatal) contacts on a computer monitor. The results from studies with children who have either articulation or phonology-based problems are discussed. Assessments of contact patterns used by articulation-impaired children suggests that they may produce more atypical articulatory contacts than are noted perceptually. Remediation, using electropalatography, showed that the children benefited from learning new articulatory gestures rather than learning to correct isolated errors. Studies with phonologically-impaired children have shown that perceptually neutralized (or non-contrasted) sounds may actually be produced with consistent articulatory contrasts. This knowledge could assist in identifying sounds that might soon emerge and be more responsive to therapy. Training studies with phonologically-impaired children have shown that a motor approach using sound contrasts to teach a phonetic inventory is an effective way to assist these children. Considerations for candidacy for EPG training are also discussed.     

Analysis of abnormal articulatory dynamics in two dysarthric patients

By means of pellet tracking techniques using an X-ray microbeam system, observations of the articulatory movements of various types of dysarthric subjects were conducted. In selected cases, electromyography (EMG) was also performed. The data were specifically examined for range, velocity, and consistency (reproducibility) of the movements of the articulators, as well as the pattern of coordination of the different articulators involved. It was found in the case of ataxic dysarthria of cerebellar origin, for example, that the dynamic patterns were best represented as a difficulty in the initiation of purposeful movements and an inconsistency of articulatory movements, particularly in the repetitive production of a monosyllable. On EMG, breakdown of the rhythmical patterns in the articulatory muscles was quite obvious in the repetition of a monosyllable. In the case of amyotrophic lateral sclerosis (ALS), decrease in the range and velocity of movements was noted. This resulted from reduced neuromuscular units (NMU) activities manifested in clinical EMG. Analysis of the dynamic aspects of the dysarthrias is a promising approach for elucidating the nature of central problems of speech production and for a differential diagnosis of various types of dysarthrias.     

The acquisition of unrounded vowels in English.

This study investigated developmental patterns of acquisition of the unrounded American English vowels /i, I, e, e, ae, a/ by following 6 normally developing children from 22 to 30 months of age. The subjects were examined at approximately 22, 26, and 30 months of age. Results showed that, in general, /i/ and /a/ were mastered early and /I/ and /e/ were least accurate throughout the period of the study. Upon inspection of errors, the following three classes of production errors were identified: (a) intertrial production variability, (b) context-sensitive substitutions, and (c) context-free systematic substitution patterns, or articulatory processes. A decrease in production variability and in the occurrence of articulatory processes with age generally coincided with a gradual improvement in accuracy of production. However, substitutions of lower vowels for /I/ were persistent, and the pattern was observed even at 30 months of age. Individual variation was also evident in the production accuracy, the substitution patterns, and the manner of articulatory improvement.     

Cortical, auditory, event-related potentials in response to periodic and aperiodic stimuli with the same spectral envelope

OBJECTIVE: 1) To determine whether the N1-P2 acoustic change complex is elicited by a change of periodicity in the middle of an ongoing stimulus, in the absence of changes of spectral envelope or rms intensity. 2) To compare the N1-P2 acoustic change complex with the mismatch negativity elicited by the same stimuli in terms of amplitude and signal to noise ratio. DESIGN: The signals used in this study were a tonal complex and a band of noise having the same spectral envelope and rms intensity. For elicitation of the acoustic change complex, the signals were concatenated to produce two stimuli that changed in the middle (noise-tone, tone-noise). Two control stimuli were created by concatenating two copies of the noise and two copies of the tone (noise-only, tone-only). The stimuli were presented using an onset-to-onset interstimulus interval of 3 sec. For elicitation of the mismatch negativity, the tonal complex and noise band stimuli were presented using an oddball paradigm (deviant probability = 0.14) with an onset-to-onset interstimulus interval of 600 msec. The stimuli were presented via headphones at 80 dB SPL to 10 adults with normal hearing. Subjects watched a silent video during testing. RESULTS: The responses to the noise-only and tone-only stimuli showed a clear N1-P2 complex to the onset of stimulation followed by a sustained potential that continued until the offset of stimulation. The noise-tone and tone-noise stimuli elicited an additional N1-P2 acoustic change complex in response to the change in periodicity occurring in the middle. The acoustic change complex was larger for the tone-noise stimulus than for the noise-tone stimulus. A clear mismatch negativity was elicited by both the noise band and tonal complex stimuli. In contrast to the acoustic change complex, there was no significant difference in amplitude across the two stimuli. The acoustic change complex was a more sensitive index of peripheral discrimination capacity than the mismatch negativity, primarily because its average amplitude was 2.5 times as large. CONCLUSIONS: These findings indicate that both the acoustic change complex and the mismatch negativity are sensitive indexes of the neural processing of changes in periodicity, though the acoustic change complex has an advantage in terms of amplitude. The results support the possible utility of the acoustic change complex as a clinical tool in the assessment of peripheral speech perception capacity.     

Presentation level determination for CV tokens using a computer-controlled adaptive procedure

The feasibility of using a computer-controlled adaptive procedure to find maximum monotic performance for consonant-vowel (CV) stimuli was evaluated and compared to the procedure typically used to determine a performance-intensity function in two experiments. In experiment I, the computer-controlled adaptive procedure and the typical manual procedure were evaluated on 26 normally hearing listeners. Results indicated that the shape of the performance-intensity functions was similar for both procedures with the computer-controlled adaptive procedure selecting a higher presentation level. The test-retest reliability for the computer-controlled adaptive procedure was good with a mean difference on retest of 1.2 dB. In experiment II, the same procedures were evaluated using 9 sensorineural hearing impaired subjects. Again similar configuration between functions was observed. The primary advantage of the computer-controlled adaptive procedure for both subject groups is efficiency in terms of time of administration and number of CV stimuli used.