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Biomedical subjects

L Schulte

Publications and source records attributed to L Schulte.

At least 19 recordsLinked to original sources
PubMed2001

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.

Articulation Disorders↗
PubMed1999

Phonatory air flow characteristics of adductor spasmodic dysphonia and muscle tension dysphonia.

The purpose of this study was to determine if phonatory air flow characteristics differed among women with adductor spasmodic dysphonia (AdSD), muscle tension dysphonia (MTD), and normal phonation. Phonatory air flow signals were gathered during [pa] syllable repetitions. Mean phonatory air flow, coefficients of variation, and the presence of large air flow perturbations (75 ml/s or more) were examined for the three groups of speakers. There was no significant difference in mean phonatory air flow across groups, and very large intersubject variation in mean phonatory air flow occurred for both the AdSD and MTD groups. Coefficients of variation were similar for the groups of women with MTD and normal phonation but were significantly larger for the group with AdSD. Air flow perturbations were common with AdSD and rare with MTD. Relatively large coefficients of variation and air flow perturbations of at least 75 ml/s did occur for some women with normal voices who were 70 years of age or older. It appears that intrasubject variability in phonatory air flow may aid in the differentiation of AdSD and MTD when used in conjunction with other elements of a thorough voice evaluation. However, the potential contribution of aging to increased intrasubject variability in phonatory air flow must be considered when interpreting findings.

Adult↗
PubMed1999

Altered phonatory physiology with short-term deactivation of children's cochlear implants.

OBJECTIVES: The purposes of this investigation were 1) to determine whether short-term auditory deprivation results in systematic phonatory changes for prelingually deafened children who use cochlear implants (CIs) and 2) to determine whether such changes are similar to those that have been reported for postlingually deafened adults. DESIGN: Participants were two 6-yr-old children with CIs. Both children had been prelingually deafened, had good to excellent speech production and speech perception skills, and had been using their CIs for 2.5 yr. A single-subject design was used. Intraoral air pressure (Po), phonatory air flow (Vl), electroglottograph (EGG) cycle width, fundamental frequency (F0), and intensity were measured during syllable production over two baseline days and three experimental days. Data were collected twice on each baseline day while the children wore their CIs, with a 1 hr break between data collection sessions. On experimental days, data were collected while the children wore their CIs (ON condition) and after their CIs had been removed for 1 hr (OFF condition). RESULTS: Both children demonstrated highly variable phonatory behaviors in baseline. The child with the more proficient speech production and perception skills showed consistent and significant reductions in Po, F0, and intensity in the OFF condition. These findings were dissimilar to those that occurred with repeated testing in the baseline condition and so were attributed to the sudden loss of auditory feedback. The other child showed a consistent and significant increase in mean Vl in the OFF condition. However, this child exhibited a similar finding with repeated testing in the baseline condition. Therefore, increased Vl in the OFF condition may have represented a practice effect. She also showed a small and consistent decrease in F0 in the OFF condition when F0 was derived from acoustic data, but this effect was not reliable in another data set when F0 was derived from the EGG signal. Our results with prelingually deafened children were inconsistent with reports of increased intensity and F0 in the absence of auditory feedback for postlingually deafened adults with CIs. CONCLUSIONS: Some prelingually deafened children who are successful CI users appear to use auditory feedback to self-monitor phonation. We suggest that the participant in our investigation who showed systematic phonatory changes in response to diminished auditory feedback was using auditory feedback primarily to stabilize her phonatory behaviors. She may not have had adequate experience with auditory feedback or adequate flexibility in her use of feedback mechanisms to implement the phonatory compensations that late-deafened adults use when auditory feedback suddenly is diminished. We further suggest that the phonatory changes that she exhibited during short-term auditory deprivation reflected disruption of her typical speaking strategies or apprehension about speaking when her ability to self-monitor auditorily was compromised.

Child↗
PubMed1998

Vowel-related differences in laryngeal articulatory and phonatory function.

The purpose of this investigation was to study the interaction between the supralaryngeal and laryngeal components of the speech mechanism by examining vowel-related effects for a variety of vocal fold articulatory and phonatory measures. Secondary issues were to determine if vowel-related differences were influenced by the nature of the speaking task or gender. Between-vowel differences in estimated subglottal air pressure, peak oral air flow, mean phonatory air flow, air flow near the termination of the vowel, electroglottograph cycle width (EGGW), fundamental frequency, and voice onset time were examined for men and women during syllable repetitions and sentence productions. Significant vowel-related differences were found for all of the measures except mean phonatory air flow, and generally were not influenced by speaking task or gender. Vowel-related effects for estimated subglottal air pressure, peak oral air flow, fundamental frequency, and VOT were consistent with some earlier studies. New findings included vowel-related differences in EGGW and air flow near the termination of the vowel. We propose a model that includes the contribution of mechanical forces, reflexive neural activity, and learned neural activity to explain vowel-related effects. When vowel height is varied, changes in laryngeal cartilage positioning and vocal fold and vocal tract tension appear to influence laryngeal articulatory and phonatory function.

Adult↗
PubMed1995

Effect of relative and overall amplitude on perception of voiceless stop consonants by listeners with normal and impaired hearing.

Previous studies of the /p/-/t/ contrast for normal-hearing listeners have shown that both manipulation of the amplitude of the burst relative to the vowel in the F4-F5 frequency region and overall presentation level can influence the perception of place of articulation [R. N. Ohde and K. N. Stevens, J. Acoust. Soc. Am. 74, 706-714 (1983); Gravel and Ohde, Asha 25, 101 (1983)], such that greater burst amplitude in the high frequencies and higher presentation levels result in more alveolar responses. The influence of relative amplitude and presentation level was tested for both normal-hearing (NH) and hearing-impaired (HI) listeners in the present study. Synthetic CV stimuli were used, and the amplitude of the burst relative to vowel-onset amplitude in the F4-F5 frequency region was manipulated across a 20-dB range. In addition, overall presentation level was varied across a 45-dB range. The findings revealed that the hearing-impaired listeners selected more alveolar responses than listeners with normal hearing when tested at equivalent SPLs. A group of five normal-hearing listeners were then presented the synthetic stimuli in a background of broadband noise at a level that produced thresholds at 4 kHz equivalent to the thresholds of five hearing-impaired listeners. Results from the noise-masked normal-hearing listeners did not consistently show more alveolar responses as presentation level of the stimuli was increased, thus failing to mimic the responses from the hearing-impaired listeners in quiet.

Adolescent↗
PubMed1994

Developmental patterns of laryngeal and respiratory function for speech production.

Estimates of subglottal air pressure, laryngeal airflow, and laryngeal airway resistance from syllable repetitions of children and adults were used in describing developmental changes in these variables and in hypothesizing corresponding changes in respiratory function. A trend was found for pressure and resistance to decrease with increases in flow from preschool age through adulthood. These patterns could be explained by the smaller size of laryngeal airway structures and increased expiratory muscle forces during speech in the younger subjects. When the subglottal air pressures were combined with published data on air volume expired during speech and recoil pressures of the respiratory system, hypothetical functions were derived for respiratory muscle forces and the work of speech breathing. These functions predict (a) a developmental shift from the use of net expiratory muscle force in the speech of preschool children to the adult patterns of combined inspiratory and expiratory muscle forces, and (b) the expiratory work of speech breathing is greater in preschool children than in older children and adults.

Adult↗
PubMed1994

Aerodynamic and electroglottographic measures of normal voice production: intrasubject variability within and across sessions.

The purpose of this investigation was to quantify the normal intrasubject performance variability of four measures of phonatory function within and across sessions. Two different speaking tasks, syllable series and sentence production, were used to determine if more natural speaking tasks resulted in greater intrasubject variability. Vowel type ([i] versus [a]) also was varied. Estimated subglottal air pressure, mean phonatory air flow, abduction quotient, and fundamental frequency were derived from aerodynamic and electroglottographic signals obtained from 11 normally speaking men and 10 normally speaking women on four different days. Relative intrasubject variability was compared across speaking task, gender, and vowel type. Average across-session intrasubject variability was 5% for fundamental frequency and abduction quotient, 8% for estimated subglottal air pressure, and 15% for mean phonatory air flow during syllable repetition. There was significantly greater intrasubject variability for mean phonatory air flow and abduction quotient for the sentence repetition task. There were no significant differences in intrasubject variability across gender and vowel type. The data were used to compute cutoff values that represent the amount of variability that would be considered within normal limits. These normal data can be used for comparison when assessing and monitoring the phonatory abilities of individuals with voice disorders.

Adult↗
PubMed1994

Physiological assessment of speech and voice production of adults with hearing loss.

The purpose of this investigation was to study the impact of hearing loss on phonatory, velopharyngeal, and articulatory functioning using a comprehensive physiological approach. Electroglottograph (EGG), nasal/oral air flow, and intraoral air pressure signals were recorded simultaneously from adults with impaired and normal hearing as they produced syllables and words of varying physiological difficulty. The individuals with moderate-to-profound hearing loss had good to excellent oral communication skills. Intraoral pressure, nasal air flow, durations of lip, velum, and vocal fold articulations, estimated subglottal pressure, mean phonatory air flow, fundamental frequency, and EGG abduction quotient were compared between the two subject groups. Data from the subjects with hearing loss also were compared across aided and unaided conditions to investigate the influence of auditory feedback on speech motor control. The speakers with hearing loss had significantly higher intraoral pressures, subglottal pressures, laryngeal resistances, and fundamental frequencies than those with normal hearing. There was notable between-subject variability. All of the individuals with profound hearing loss had at least one speech/voice physiology measure that fell outside of the normal range, and most of the subjects demonstrated unique clusters of abnormal behaviors. Abnormal behaviors were more evident in the phonatory than articulatory or velopharyngeal systems and were generally consistent with vocal fold hyperconstriction. There was evidence from individual data that vocal fold posturing influenced articulatory timing. The results did not support the idea that the speech production skills of adults with moderate-to-profound hearing loss who are good oral communicators deteriorate when there are increased motoric demands on the velopharyngeal and phonatory mechanism. Although no significant differences were found between the aided and unaided conditions, 7 of 10 subjects showed the same direction of change for subglottal pressure, intraoral pressure, nasal air flow, and the duration of lip and vocal fold articulations. We conclude that physiological assessments provide important information about the speech/voice production abilities of individuals with moderate-to-profound hearing loss and are a valuable addition to standard assessment batteries.

Adult↗
PubMed1994

Sarcoplasmic reticulum Ca2+ pump expression in denervated skeletal muscle.

This study was undertaken as one approach to better understand how contractile activity regulates excitation-contraction coupling phenotype in skeletal muscle. The effects of denervation on the expression of the sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase), a key protein of the contraction-relaxation cycle, was analyzed in fast-twitch (FT) and slow-twitch (ST) skeletal muscle. Muscle mass, mRNA, and protein expression of specific isoforms of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) and contractile parameters related to muscle relaxation were measured in rat soleus and extensor digitorum longus (EDL) muscles at 1, 4, 7, 14, and 28 days after sciatic nerve transection. Wet muscle mass decreased to 35% of control by 28 days of denervation in both soleus and EDL muscles (P < 0.05). Northern and Western analyses showed decreases in mRNA and protein expression of the slow Ca2+ pump isoform (SERCA2a) in the denervated soleus muscle and in the fast Ca2+ pump isoform (SERCA1) in the denervated EDL muscle, particularly at later time points. There was no change in the expression of the alternate isoform in either muscle type. Prolongation of twitch contraction times, slowed rates of tension development, and leftward shifts in frequency-tension curves were consistent with the reduced Ca2+ pump density and suggested slowed Ca2+ handling in SR or denervated ST and FT muscles. The results are in marked contrast with those previously reported in non-weight-bearing muscle induced by biomechanical unloading.

Animals↗
PubMed1994

Hearing research career development for deaf students.

One goal of the Americans with Disabilities Act is to enhance access to career opportunities for individuals with hearing loss. Hearing-impaired professionals are woefully underrepresented among the cadre of scientists currently involved in hearing and deafness research. Information was obtained by questionnaire from 190 consecutive attendees (13 through 17 years of age) at a summer program for gifted hearing-impaired adolescents regarding career goals, attitudes toward academic and extracurricular activities, educational placement, primary communication modality, and parental hearing status. A follow-up questionnaire completed by 80 of these youth, presently attending college, provided comparison data regarding type of college attended and academic major. Males were significantly more likely to select majors in mathematics and science-related disciplines. The percentage of college attendees majoring in the sciences was much lower than the percentage of high school students who aspired to a scientific career. Strategies for attracting qualified hearing-impaired students into science majors should include educational efforts directed at students, parents, and academic advisors.

Adolescent↗
PubMed1993

A quantitative assessment of limited joint mobility in patients with diabetes. Goniometric analysis of upper extremity passive range of motion.

OBJECTIVE: The syndrome of limited joint mobility is a common but not widely recognized musculoskeletal complication of diabetes. The purpose of this study was to further characterize this syndrome using quantitative goniometric measures. METHODS: Cross-sectional analysis of a sample population was performed to establish the prevalence, location, and severity of limited joint mobility and to determine its relationship to extraarticular manifestations and complications of diabetes. Passive range of motion of both upper extremities was measured by goniometry in 70 adult patients with insulin-dependent diabetes mellitus and 70 nondiabetic controls who were group-matched for age, sex, and general activity level. Joint mobility was assessed by both individual joint motions and a composite scoring technique. RESULTS: Analysis of individual joints and composite scores revealed significant differences between dominant and nondominant extremities in both the control and the diabetic groups. Diabetic patients were generally less flexible than nondiabetic subjects throughout the arm, especially in shoulder and finger joints. In the full study population, multivariate analysis revealed that advanced age, male sex, and the presence of diabetes were associated with decreased passive range of motion for a majority of joints (P < 0.05). In the diabetes group, passive range of motion was significantly correlated (P < 0.05) with age, sex, duration of diabetes, and to a variable extent, glucose control, but was not correlated with the presence of clinically significant neuropathy, retinopathy, nephropathy, or peripheral vascular disease, with activity level, or with hand dominance. Stepwise regression analysis failed to identify single key joint motion(s) to serve as possible screening tests in predicting generalized limited joint mobility of the upper extremity. Finally, the effect of limb usage on range of motion in flexion may differ in diabetic and nondiabetic subjects. CONCLUSION: Limited joint mobility is a generalized phenomenon occurring throughout the upper extremities of many diabetic patients. It is significantly related to age, sex, and to a variable extent duration of diabetes and glucose control. It is not related to the standard complications of diabetes as defined in this study.

Adult↗
PubMed1993

A comparison of transient-evoked and distortion product otoacoustic emissions in normal-hearing and hearing-impaired subjects.

The ability of transient-evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) to distinguish normal hearing from hearing impairment was evaluated in 180 subjects. TEOAEs were analyzed into octave or one-third octave bands for frequencies ranging from 500 to 4000 Hz. Decision theory was used to generate receiver operating characteristic (ROC) curves for each of three measurements (OAE amplitude, OAE/noise, reproducibility) for each OAE measure (octave TEOAEs, 1/3 octave TEOAEs, DPOAEs), for octave frequencies from 500 to 4000 Hz, and for seven audiometric criteria ranging from 10 to 40 dB HL. At 500 Hz, TEOAEs and DPOAEs were unable to separate normal from impaired ears. At 1000 Hz, both TEOAE measures were more accurate in identifying hearing status than DPOAEs. At 2000 Hz, all OAE measures performed equally well. At 4000 Hz, DPOAEs were better able to distinguish normal from impaired ears. Almost without exception, measurements of OAE/noise and reproducibility performed comparably and were superior to measurements of OAE amplitude, although the differences were small. TEOAEs analyzed into octave bands showed better performance than TEOAEs analyzed into 1/3 octaves. Under standard test conditions, OAE test performance appears to be limited by background noise, especially for the low frequencies.

Acoustic Stimulation↗
PubMed1992

Coupling of FM systems to individuals with unilateral hearing loss.

This study examined the attenuation characteristics of five FM system sound delivery options for a group of 10 adults and 15 children (5-13 years). Sound delivery options included a tube-fitting, lightweight headphones, a CROS earmold with tubing, a CROS earmold with a snap-ring, and a standard snap-ring earmold with a vent. Attenuation was defined as the difference between probe-tube microphone measures of the ear canal resonance and the SPL in the ear canal with each sound delivery option in place. A statistically significant but clinically inconsequential difference in attenuation for the CROS earmold with tubing was noted between adults and children. No significant differences in attenuation for any of the other sound delivery options were noted between adults and children. An investigation of the relationship between magnitude of attenuation and percentage of the ear canal occluded suggests that degree of occlusion is a major factor in determining degree of attenuation provided by a particular sound delivery option. Results also indicate that significant attenuation of high-frequency signals can occur with earmolds commonly considered nonoccluding. Caution should be used in fitting hearing aids or FM systems to individuals with normal high-frequency hearing sensitivity to prevent attenuation of unamplified high-frequency speech information.

Adult↗
PubMed1992

Equivalent ear canal volumes in children pre- and post-tympanostomy tube insertion.

Pre- and postoperative equivalent ear canal volume measures were obtained from a group of 334 children ranging in age from 6 weeks to 6.7 years. The purpose of the study was to develop volumetric guidelines for the determination of tympanostomy tube patency. For children 4 years and older, almost no ambiguity existed in making this determination accurately. For younger children, the pre- and postoperative distributions overlap. A criterion value of greater than or equal to 1.0 cm3 as an indicator of a tympanic membrane perforation appears to yield the lowest possible error rate. When both pre- and postoperative measures are available, a difference of greater than or equal to 0.4 cm3 can be used in conjunction with the absolute value to identify a patent tympanostomy tube.

Acoustic Impedance Tests↗
PubMed1992

Regulation of skeletal muscle dihydropyridine receptor gene expression by biomechanical unloading.

Biomechanical unloading of the rat soleus by hindlimb unweighting is known to induce atrophy and a slow- to fast-twitch transition of skeletal muscle contractile properties, particularly in slow-twitch muscles such as the soleus. The purpose of this study was to determine whether the expression of the dihydropyridine (DHP) receptor gene is upregulated in unloaded slow-twitch soleus muscles. A rat DHP receptor cDNA was isolated by screening a random-primed cDNA lambda gt10 library from denervated rat skeletal muscle with oligonucleotide probes complementary to the coding region of the rabbit DHP receptor cDNA. Muscle mass and DHP receptor mRNA expression were assessed 1, 4, 7, 14, and 28 days after hindlimb unweighting in rats by tail suspension. Isometric twitch contraction times of soleus muscles were measured at 28 days of unweighting. Northern blot analysis showed that tissue distribution of DHP receptor mRNA was specific for skeletal muscle and expression was 200% greater in control fast-twitch extensor digitorum longus (EDL) than in control soleus muscles. A significant stimulation (80%) in receptor message of the soleus was induced as early as 24 h of unloading without changes in muscle mass. Unloading for 28 days induced marked atrophy (control = 133 +/- 3 vs. unweighted = 62.4 +/- 1.8 mg), and expression of the DHP receptor mRNA in the soleus was indistinguishable from levels normally expressed in EDL muscles. These changes in mRNA expression are in the same direction as the 37% reduction in time to peak tension and 28% decrease in half-relaxation time 28 days after unweighting. Our results suggest that muscle loading necessary for weight support modulates the expression of the DHP receptor gene in the soleus muscle.

Animals↗
PubMed1992

Auditory brainstem responses elicited by 1000-Hz tone bursts in patients with sensorineural hearing loss.

Auditory brainstem responses were measured in response to 1000-Hz tone bursts from 115 patients with sensorineural hearing loss, presumably of cochlear origin. Mean wave V latencies and variability were comparable to those observed in normal hearing subjects for similar stimuli. The range of interaural differences in wave V latencies for 1000-Hz tone bursts were slightly greater than those observed for clicks, which may not be surprising, given the greater variability in wave V latencies for tonal stimulation, even in normal-hearing subjects. These differences, however, were not affected either by the magnitude or symmetry of hearing loss for frequencies at and above 1000 Hz. These data suggest that tone burst ABRs might be useful in otoneurologic evaluations, especially for patients with asymmetric hearing loss.

Acoustic Stimulation↗
PubMed1991

Localization ability in infants with simulated unilateral hearing loss.

This study investigated the feasibility of using a localization task to rule out unilateral hearing loss in infants. Fourcorner localization ability was assessed in 29 normal-hearing infants (9-20 mo) using four different test stimuli. In these same infants, a mild unilateral hearing loss was simulated by occlusion of the external auditory canal and the test sequence was repeated. Analysis of front-back, right-left, and combined errors for each of the test stimuli revealed that this type of task may allow detection of unilateral hearing loss as slight as 25 dB HL.

Acoustic Stimulation↗