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PubMed1990

Spectral differences in the ABRs of old and young subjects.

The purpose of the present study was to analyze and compare the amplitude spectra of ABRs recorded from 40 elderly and 40 young subjects in order to determine if there are any age related differences. A spectral analysis was performed on each subject's ABR. It was found that the ABRs recorded from older subjects have a significantly greater amount of low frequency spectral energy than ABRs recorded from young subjects. This difference was attributed to the greater amount of low frequency background noise found in the ABRs of older subjects. Modification of standard recording procedures should be considered when ABRs are recorded from older subjects.

Adolescent↗
PubMed1991

Middle latency auditory evoked potentials in temporal lobe disorders.

Middle latency auditory evoked potentials (MAEP) were recorded in 30 normal subjects and in 19 age-matched patients with temporal lobe lesions. MAEP appeared to be differentially affected by the specific structures involved within the temporal lobe. In the majority of patients with lesions involving the auditory area and/or auditory radiation, Na-Pa amplitude was significantly reduced over the involved hemisphere. No similar reduction in amplitude was noted in subjects with lesions not involving the auditory structures within the temporal lobe. We also observed a shift in a Pa latency over the involved hemisphere in patients with temporal lobe lesions involving the auditory structures. This latency shift was less pronounced than the amplitude reduction. The generators of MAEP in humans are discussed according to these findings and to the available literature. Normal intersubject variability of the conventional amplitude measures, and the occasional myogenic contamination of the response, limits establishing reliable criteria for abnormality that can be applied clinically for the diagnosis of patients with temporal lobe disorders.

Acoustics↗
PubMed1992

Frequency specificity of the auditory brain stem response to bone-conducted tones in infants and adults.

Auditory brain stem responses were obtained from normal-hearing infants and adults in response to bone-conducted 500 and 2000 Hz tones presented in quiet and high-pass noise masking. The tones were presented at 70 (500 and 2000 Hz) and 46 (2000 Hz) dB peak to peak equivalent (re: 1 dyne RMS). The high-pass noise-masked waveforms were subtracted in succession to obtain derived responses, providing estimates of the cochlear regions contributing to the nonmasked responses. Findings indicate that the auditory brain stem response to bone-conducted 500 Hz tones is frequency specific for both infants and adults. For 2000 Hz tones, the results show maximum amplitudes for cochlear regions representing the nominal frequency of the tone for adults. For infants, maximum response amplitudes for the derived responses to 2000 Hz, 70 dB tones were obtained within 1/2 octave of the nominal frequency (1410-2000 Hz). Wave V latencies of the derived responses are similar for both groups for 2000 Hz tones, but shorter for infants to 500 Hz tones, supporting the hypothesis that low-frequency bone-conducted stimuli are effectively more intense in infants than adults.

Acoustics↗
PubMed1992

Noise reduction hearing aids: release from masking and release from distortion.

Automatic frequency response (AFR) hearing aids usually reduce their low-frequency gain in the presence of noise; several investigators have reported improved recognition of high-frequency speech information in low-frequency band-limited noise with AFR versus non-AFR hearing aids. In this work, masking patterns (masked threshold for frequency-modulated probe tones as a function of probe frequency) were obtained for a narrowband low-frequency noise. Speech recognition threshold for a set of high-frequency loaded monosyllables also was obtained in the presence of the same noise. Aided speech and masking pattern data for one normal and two hearing-impaired subjects wearing a master hearing aid incorporating a commercially available AFR circuit showed modest AFR effects. Moreover, masking noise spectra measured in ear canals of subjects wearing the master hearing aid showed evidence of substantial hearing aid-generated distortion products in the AFR-off condition. Results obtained from the normal subject listening with a low-distortion laboratory simulation of an AFR hearing aid showed greater release from masking for the same low-frequency attenuation as provided by the hearing aid. Improvements of speech recognition in noise observed with AFR hearing aids may result from some combination of release from upward spread of masking and reduction of distortion products generated by the hearing aid in the non-AFR setting.

Adult↗
PubMed1992

Effects of noise and noise suppression on speech perception by cochlear implant users.

The recognition of phonemes in consonant-vowel-consonant words, presented in speech-shaped random noise, was measured as a function of signal to noise ratio (S/N) in 10 normally hearing adults and 10 successful adult users of the Nucleus cochlear implant. Optimal scores (measured at a S/N of +25 dB) were 98% for the average normal subject and 42% for the average implantee. Phoneme recognition threshold was defined as the S/N at which the phoneme recognition score fell to 50% of its optimal value. This threshold was -2 dB for the average normal subject and +9 dB for the average implantee. Application of a digital noise suppression algorithm (INTEL) to the mixed speech plus noise signal had no effect on the optimal phoneme recognition score of either group or on the phoneme recognition threshold of the normal group. It did, however, improve the phoneme recognition threshold of the implant group by an average of 4 to 5 dB. These findings illustrate the noise susceptibility of Nucleus cochlear implant users and suggest that single-channel digital noise reduction techniques may offer some relief from this problem.

Adult↗
PubMed1995

Event-related potentials and the categorical perception of speech sounds.

OBJECTIVE: To determine whether there are physiological correlates of categorical perception. DESIGN: Human evoked potentials were recorded in response to computer-modified speech sounds from a nine-stimulus continuum between /ba/ and /da/. In the first experiment, subjects listened to trains composed of 52% /ba/ or /da/ and 6% of each of the other eight stimuli and classified the stimuli as "ba" or "da." In the second experiment, subjects read a book and ignored trains containing a standard stimulus (p = 80%) and two deviant speech sounds (p = 10% each), one within the same category as the standard and the other across the category-boundary. The third experiment was similar to the first except that the subject was reading. The fourth experiment compared the responses to stimuli that deviated from standards in terms of their phonemic category or intensity. RESULTS: An N2-P3 complex was evoked by those stimuli in the more improbable category when the stimuli were attended to in the first experiment. In the second and third experiments, there was a clear mismatch negativity (MMN) for the across-category deviant stimuli when the standard stimulus came from the /ba/ end of the continuum. However, when the standard stimulus came from the /da/ end of the continuum, there was no definite MMN. The overall frequency-content of our /da/ stimulus was broader than that of the /ba/ stimulus. A deviant stimulus from the /da/ end of the continuum thus contained frequencies which were not present in the /ba/-standard stimuli and these frequencies could elicit a MMN. In the fourth experiment the MMN evoked by a small change in intensity was much larger than that evoked by a change in phonemic category. CONCLUSIONS: The N2-P3 complex accurately reflects the phonemic categorization of speech stimuli. The MMN evoked by changes in speech sounds may indicate the detection of acoustic rather than phonetic changes.

Adult↗
PubMed1996

Identification of speech by cochlear implant recipients with the Multipeak (MPEAK) and Spectral Peak (SPEAK) speech coding strategies. I. Vowels.

OBJECTIVE: The main objective was to evaluate differences in performance associated with the two speech coding strategies. To achieve this objective, acoustic and electrical analyses of vowels identified by cochlear implant recipients were compared with their responses when they used the Multipeak (MPEAK) and the Spectral Peak (SPEAK) speech coding strategies of the Nucleus Cochlear Implant System. DESIGN: Nine subjects identified pure and r-colored English vowels with the two speech coding strategies. The two processing strategies were compared using an ABAB design. Evaluations were conducted at two weekly sessions after at least 3 wk of use with each strategy. RESULTS: Group vowel identification scores with the MPEAK versus the SPEAK strategy were not significantly different (72.3% and 73.4%, respectively). However, hierarchical loglinear analysis of group data showed that transmitted information of r-color, duration, and second-formant features was significantly better with the SPEAK than with the MPEAK strategy. In contrast, identification of the first formant feature was significantly better with the MPEAK than with the SPEAK strategy. Individual subjects had different error patterns in response to the 14 vowels. CONCLUSIONS: Electrical stimulation with the SPEAK strategy provides clearer spectral representation of second formant and duration information as well as second and third formant change in r-colored vowels than with the MPEAK strategy. Consequently, there was marked improvement in recognition of r-colored vowels with SPEAK compared with MPEAK. In contrast, transmitted information for first-formant features was significantly less with SPEAK than with MPEAK. This may have occurred because four instead of six to eight electrodes were assigned to first formant frequencies with SPEAK versus MPEAK.

Adult↗
PubMed2001

The contribution of amplitude envelope cues to sentence identification in young and aged listeners.

OBJECTIVE: The purpose of this study was to examine the importance of amplitude envelope cues to sentence identification for aged listeners. We also examined the effect of increasing alterations (i.e., compression ratio) and amount of available frequency content (i.e., number of channels) for this population. DESIGN: Thirty-six listeners were classified according to their age (35 or younger versus 65 and older) and hearing status (normal hearing versus hearing impaired). Within each hearing status, mean hearing threshold thresholds for the young and aged listeners were matched as closely as possible through 4 kHz to control for sensitivity differences across age, and all listeners passed a cognitive screening battery. Accuracy of synthetic sentence identification was measured using stimuli processed to restrict spectral information. Performance was measured as a function of age, hearing status, amount of spectral information, and degradation of the amplitude envelope (using fast-acting compression with compression ratios ranging from 1:1 to 5:1). RESULTS: Mean identification scores decreased significantly with increasing age, the presence of hear- c ing loss, the removal of spectral information, and with increasing distortion of the amplitude envelope (i.e., higher compression ratios). There was a consistent performance gap between young and aged listeners, regardless of the magnitude of change to the amplitude envelope. This suggests that some cue other than amplitude envelope variations is inaccessible to the aged listeners. CONCLUSIONS: Although aged listeners performed more poorly overall, they did not show greater susceptibility to alterations in amplitude-envelope cues, such as those produced by fast-acting amplitude compression systems. It is therefore unlikely that compression parameters such as attack and release time or compression ratio would need to be a differentially programmed for aged listeners. Instead, the data suggest two possibilities: aged listeners have difficulty accessing the fine-structure temporal cues present in speech, and/or performance is degraded by age-related loss of function at a central processing level.

Adult↗
PubMed2002

Effects of sensorineural hearing loss on cortical event-related potential and behavioral measures of speech-sound processing.

OBJECTIVE: To investigate systematically the effects of sensorineural hearing loss on cortical event-related potentials (ERPs) N1, MMN, N2 and P3 and their associated behavioral measures (d' sensitivity and reaction time) to the speech sounds /ba/ and /da/ presented at 65 and 80 dB ppe SPL. DESIGN: Cortical ERPs were recorded to /ba/ and /da/ speech stimuli presented at 65 and 80 dB ppe SPL from 20 normal-hearing adults and 20 adults who are hearing impaired. The degree of sensorineural impairments at 1000 to 2000 Hz ranged from mild losses (defined as 25 to 49 dB HL) to severe/profound losses (75 to 120 dB HL). The speech stimuli were presented in an oddball paradigm and the cortical ERPs were recorded in both active and passive listening conditions for each stimulus intensity. RESULTS: Both ERP amplitudes and behavioral discrimination (d') scores were lower for listeners with sensorineural hearing loss than for those with normal hearing. However, these differences in response strength were evident only for those listeners whose average hearing loss at 1000 to 2000 Hz exceeded 60 dB HL for the lower intensity stimuli and exceeded 75 dB HL for the higher intensity stimuli. In contrast, prolongations in the ERP and behavioral latencies, relative to responses from normal-hearing subjects, began with even mild (25 to 49 dB HL) threshold elevations. The amplitude and latency response changes that occurred with sensorineural hearing loss were significantly greater for the later ERP peaks (N2/P3) and behavioral discrimination measures (d' and RT) in comparison with earlier (N1, MMN) responses. CONCLUSIONS: The results indicate that latency measures are more sensitive indicators of the early effects of decreased audibility than are response strength (amplitude, d' or percent correct) measures. Sensorineural hearing loss has a greater impact on higher level or "nonsensory" cortical processing in comparison with lower level or "sensory" cortical processing. Possible physiologic mechanisms within the cortex that may be responsible for these response changes are presented. Lastly, the possible clinical significance of these ERP and behavioral findings is discussed.

Adult↗
PubMed1981

The Psychological Stress Evaluator as a clinical assessment instrument. Evaluation and implications.

Efficient clinical assessment of anxiety and hostility could be facilitated through the use of a mechanical measurement instrument with known validity and reliability. Preliminary evaluation of the Psychological Stress Evaluator (PSE) has indicated that it could be used for this purpose. The present study reports the results of a correlational analysis between a PSE generated stress indicator (blocking pattern mode III) and the Gottschalk-Gleser Free Association Test, a verbal content-analysis measure of anxiety and hostility in psychotherapy patients. Findings do not show any correlation between these measures and suggest that the PSE may have only limited use as a valid and reliable assessment instrument for anxiety and hostility. Methodological problems inherent in the calculation and interpretation of PSE scores are elaborated in a review of current PSE scoring systems. A brief discussion of the theoretical assumptions underlying the development of the PSE and associated scoring protocols suggests directions for future research.

Adult↗
PubMed1996

Characteristics of an in vivo canine model of phonation with a constant air pressure source.

Many previous studies of laryngeal biomechanics using in vivo models have employed a constant air How source. Several authors have recently suggested that the lung-thorax system functions as a constant pressure source during phonation. This study describes an in vivo canine system designed to maintain a constant peak subglottic pressure (Psub) using a pressure-controlling mechanism. Increasing levels of recurrent laryngeal nerve (RLN) stimulation resulted in a significant rise in resistance followed by a plateau. For a given Psub, flow decreased significantly and precipitously with increasing stimulation and then quickly plateaued. Vocal intensity increased with increasing RLN stimulation until a peak was reached. After this peak, intensity dropped until a plateau was reached, corresponding to the flow minimum. At a given Psub, increasing levels of RLN stimulation resulted in a normal distribution of vocal efficiencies.

Airway Resistance↗
PubMed1996

Objective assessment of snoring before and after laser-assisted uvulopalatoplasty.

Laser-assisted uvulopalatoplasty (LAUP) is an outpatient staged surgical procedure for the treatment of snoring. Each patient undergoes a series of procedures with the end point being patient and bed partner satisfaction in most cases. The purpose of this study was to objectively evaluate the frequency, pattern, and volume of snoring in patients prior to and following each LAUP procedure. A sonographic device, SNAP, which records oronasal respiration, was used to assess patients at home. A digital analysis of the frequency, pattern, and volume was then performed. Twenty-seven patients have been completely evaluated with this recording device. The findings demonstrate that the LAUP procedure alters the snoring sound. The maximum, average, and velum-like respiratory noise loudness all showed a statistically significant decrease when comparing the preoperative snoring to the final recording after treatment was completed. In addition, the fundamental frequency of the snoring increased significantly after each LAUP procedure. No change was seen in the snoring index following treatment. These objective results correlated well with the subjective responses of the patients and their bed partners. These findings are consistent with the hypothesis that the LAUP procedure alters snoring in a favorable manner by both objective data and subjective accounts.

Female↗
PubMed2000

Effects of adductor muscle stimulation on speech in abductor spasmodic dysphonia.

OBJECTIVE: To determine whether adductor laryngeal muscle stimulation might be a beneficial treatment alternative for abductor spasmodic dysphonia (ABSD). STUDY DESIGN: Baseline comparisons were made on measures of voiceless consonant and syllable duration between patients with ABSD and normal control subjects, and speech and voice production with and without muscle stimulation were compared within 10 patients with ABSD. METHODS: Baseline group comparisons were conducted on measures of syllable and voiceless consonant duration between the patients and the control subjects. Neuromuscular stimulation was applied to the thyroarytenoid or lateral cricoarytenoid muscles in the patients during extended phonation, and measures were made of fundamental frequency and sound pressure level in the stimulated and nonstimulated conditions. Voiceless consonant duration was compared with and without adductor laryngeal muscle stimulation during syllable repetitions and sentences in the patients. RESULTS: Before stimulation, the patients had increased syllable durations in comparison with control subjects (P = .003). Repeated within-patient comparisons with and without stimulation demonstrated significant (P < .008) reductions in voiceless consonant durations during syllable repetition. The more severely affected patients had the greatest reductions in voiceless consonant duration during sentence production. CONCLUSIONS: Adductor muscle stimulation improved speech production in patients with ABSD, and the improvement was greatest in the most severely affected patients. Therefore adductor muscle stimulation has potential for benefiting patients with ABSD.

Adult↗
PubMed2001

Alternative voice after laryngectomy using a sound-producing voice prosthesis.

OBJECTIVE: To improve the voice quality of female laryngectomees and/or laryngectomees with a hypotonic pharyngoesophageal (PE) segment by means of a pneumatic artificial source of voice incorporated in a regular tracheoesophageal (TE) shunt valve. STUDY DESIGN: Experimental, randomized, crossover trial. METHODS: The new sound source consists of a single silicone lip, which performs an oscillatory movement driven by expired pulmonary air flowing along the outward-striking lip through the TE shunt valve. A prototype of this pneumatic sound source is evaluated in vitro and in six laryngectomees. In vivo evaluation includes speech rate, maximal phonation time, perceptual voice evaluation of read-aloud prose by an expert listener, speech intelligibility measurements with 12 listeners, and self-assessment by the patients. Moreover, extensive acoustical and aerodynamic in vivo registrations are performed using a newly developed data acquisition system. RESULTS: The current prototype seems beneficial in female laryngectomees with a hypotonic PE segment only. For them the sound-producing voice prosthesis improves voice quality and increases the average pitch of voice, without decreasing intelligibility or necessitating other pressure and airflow rates than regular TE shunt speech. Pitch regulation of this prosthetic voice is possible, yet limited. CONCLUSIONS: The mechanism is feasible and does not result in unacceptable airflow resistance. For this new mechanism of alaryngeal voice to become an established technique for postlaryngectomy voice restoration, a voice suitably pitched for male laryngectomees has to be generated and a large part of the melodic and dynamic range of the sound source has to be attainable within physiological airflow rates.

Aged↗
PubMed2001

DiHA (dextranomers in hyaluronan) injections for treatment of insufficient closure of the vocal folds: early clinical experiences.

OBJECTIVE: To determine the clinical effects of injecting DiHA (a mixture of dextranomer molecules and 1% hyaluronan solution in equal proportions) as a "space filler" into the vocal folds of patients experiencing insufficient closure of the vocal folds resulting from either unilateral vocal fold paralysis or bowed vocal folds. STUDY DESIGN: A consecutive series of patients with insufficient closure of the vocal folds treated with DiHA injections and prospectively followed up with videostroboscopy and voice recordings that were evaluated by expert panels. METHODS: During a 21/2-year period, 14 patients with insufficient closure of the vocal folds were included. Six had a unilateral vocal fold palsy and 8 patients had "bowed" vocal folds. DiHA was injected into one vocal fold. Laryngoscopic examination and voice recordings were performed pre- and postoperatively. Expert panels did the evaluation of the stroboscopy examination and the perceptual voice analysis. RESULTS: Three patients were operated on with local and 11 under general anesthesia. All patients with unilateral palsy improved their stroboscopic status regarding both the wave and the closure after injection. Also, their voice parameters were significantly improved. Among the patients with bowed vocal folds, all except 2 showed an improvement in the glottic wave, 5 of 8 improved in glottic closure, and 3 improved their voice parameters significantly. CONCLUSION: This early clinical experience indicates that DiHA fulfills most of the requirements of an ideal "space-filling" substance for voice restoration in patients experiencing insufficient vocal fold closure.

Adult↗
PubMed2002

Nasalance, nasality, voice, and articulation after uvulopalatopharyngoplasty.

OBJECTIVES/HYPOTHESIS: The main purpose of the study was to determine the impact of uvulopalatopharyngoplasty (UPPP) on nasalance and nasality. It was hypothesized that nasalance would change from the presurgical to the postsurgical condition because the surgical protocol involves removal of palatal tissue. An additional objective of the study was to provide objective and subjective data about changes in voice and articulation after UPPP. Because the surgical procedure of UPPP does not involve laryngeal tissue, it was hypothesized that the voice characteristics remain relatively stable. Because of removal of effective velar length, articulation problems of the uvular /R/ can occur in the Dutch language. STUDY DESIGN: Prospective study in which 26 men were studied before (1 week before UPPP) and after (3 weeks after UPPP) surgery. METHODS: The Nasometer was used to obtain nasalance scores. The mirror-fogging test, a perceptual evaluation of each subject's readings, and the Gutzmann and the Bzoch hypernasality tests were used for the assessment of nasality. For the assessment of articulation, a phonetic analysis was performed. Voice assessment included a perceptual rating of the voice and a determination of fundamental frequency. RESULTS: No significant differences were found between the conditions before and after surgery regarding nasalance (except for the vowel /i/), nasality, and voice. Regarding articulation, only 1 patient showed a derhotacized /R/. CONCLUSIONS: The findings of the study indicate that UPPP does not have an impact on nasality, voice, and articulation. Regarding nasalance, no significant nasalance change occurred after UPPP, except for the high vowel /i/.

Adult↗
PubMed2003

Noise in magnetic resonance imaging: no risk for sensorineural function but increased amplitude variability of otoacoustic emissions.

OBJECTIVES: Objectives were to perform exact measurements of the noise exposure in a magnetic resonance imager and to investigate the effects of magnetic resonance imaging (MRI) noise on hearing sensitivity, which are still controversial, in a large number of patients. STUDY DESIGN: Prospective trial. METHODS: Acoustic noise during seven different MRI sequences was measured using a custom-made microphone containing no ferromagnetic parts. In 244 ears of 126 patients, pure-tone audiometry was performed once before and once after MRI noise, and distortion product otoacoustic emissions were measured once before and three times after MRI. RESULTS: The sound pressure level (SPL) at the patient's ear (with consideration of the sound-damping effect of the head support) ranged from 79.5 to 86.5 dB (A), depending on the MRI sequence, with brief sound pressure peaks up to 120 dB SPL. No significant incidence of temporary threshold shift and no reduction of mean distortion product otoacoustic emission amplitude were apparent. However, a significant increase in distortion product otoacoustic emission amplitude variability after noise exposure with equal distribution of increased and decreased amplitudes was observed. This variability showed a maximum at 15 minutes after noise, as demonstrated by continuous measurements. CONCLUSIONS: First, MRI noise does not impose a risk to hearing function under the measurement condition of a sound-damping head support or ear protectors. Second, a subtle effect is demonstrated by increased distortion product otoacoustic emission amplitude variability. Third, the increased otoacoustic emission amplitude variability is an audiometric parameter that is extremely sensitive to effects of acoustic stimulation, indicating more discrete changes in cochlear activity than pure-tone audiometry or otoacoustic emission amplitude reduction. A shift of the operation point (OP) of the outer hair cell (OHC) between basilar membrane and tectorial membrane is suggested as underlying cause.

Audiometry, Pure-Tone↗
PubMed2003

Role of mannitol in reducing postischemic changes in distortion-product otoacoustic emissions (DPOAEs): a rabbit model.

OBJECTIVES: The aim of this study was to observe the effects of mannitol, administered topically at the round window (RW), on cochlear blood flow (CBF) and distortion-product otoacoustic emission (DPOAE) after repeated episodes of cochlear ischemia. METHODS: Ten young rabbits were used for this study. Reversible ischemic episodes within the cochlea were induced by directly compressing the internal auditory artery (IAA). CBF was measured using a laser-Doppler (LD) probe positioned at the RW niche. DPOAEs were measured at 4, 8, and 12 kHz geometric mean frequency (GMF) using 60 dB sound pressure level (SPL) primary tone stimuli. In five test ears, mannitol was administered topically at the RW for 30 minutes before the IAA compressions. In five control ears, the IAA compressions were undertaken without application of RW medication. Each ear underwent three 5 minute IAA compressions with a 60 minute rest period between compressions. RESULTS: In the control animals, it was observed that a progressive reduction in DPOAE level followed each successive IAA compression at all three test frequencies. The reduction in DPOAE amplitudes was consistently greater at the higher test frequencies. In the test rabbits, the RW administration of mannitol resulted in significantly less reduction in DPOAE level measures after repeated IAA compressions. For example, 30 minutes after reperfusion at 12 kHz GMF, DPOAE levels in the control ears were reduced by 1.5, 6.0, and 16 dB, compared with 1.5, 4.0, and 6.0 dB in the mannitol test ears. CONCLUSIONS: Mannitol appears to exert a protective effect on cochlear function after periods of ischemia. The RW appears to be an efficacious route for topical administration of mannitol into the inner ear.

Acoustic Stimulation↗