PubMed Health⌕ Search

Biomedical subjects

M Hannley

Publications and source records attributed to M Hannley.

9 recordsLinked to original sources
PubMed1990

Laryngeal brainstem evoked response: a developmental study.

A developmentally receding laryngeal chemoreflex (LCR) has been described in infant animals of several species characterized by vocal cord adduction in response to laryngeal stimulation as well as a potentially fatal cardio-respiratory response. Age-related differences in the brainstem respiratory centers may account for differences in the LCR and play a role in such disorders as Sudden Infant Death Syndrome (SIDS) and infant apnea. Study of the LCR at the brainstem level could provide insights into normal maturation of respiratory centers and eventually the pathophysiology of these disorders. The present study evaluated the laryngeal brainstem response (LBR) evoked by electrical stimulation of the superior laryngeal nerve in kittens using a far-field technique similar to auditory brainstem response testing. Recordings were obtained via posterior pharyngeal and posterior cervical recording sites and compared to results previously obtained in our laboratory for adult cats. The LBR in kittens demonstrated differences in threshold, latencies, and morphology which suggests that postnatal maturation of laryngeal function at the brainstem level does occur.

Aging↗
PubMed1989

Laryngeal brain stem evoked response.

Sensory stimuli to the larynx evoke a laryngeal adductor reflex mediated by the brain stem via superior and recurrent laryngeal nerves. Aberrant laryngeal reflexes have been proposed to explain a number of poorly understood disorders, including "reflex apnea," idiopathic laryngospasm, and sudden infant death syndrome. The purpose of the present study was to evaluate far field brain stem recordings following stimulation of the superior laryngeal nerve to determine whether laryngeal brain stem response is a valid measure of laryngeal activity at the brain stem level. The nerve was stimulated electrically in adult cats, and the resultant laryngeal adductor response as well as far field brain stem activity was recorded. For the latter, six reproducible positive and five reproducible negative waves were obtained via posterior pharyngeal (+) and posterior cervical (-) recording electrodes. Response threshold and latencies were measured and evaluated as a function of stimulus parameters. Wave latencies corresponded closely to those reported in prior near and far field evoked response recordings.

Animals↗
PubMed1986

Influence of the acoustic reflex on vowel recognition.

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

Air Pressure↗
PubMed1985

Patterns of phoneme identification error in cochlear and eighth-nerve disorders.

The purpose of this study was to determine whether patterns of phoneme identification error differ among listeners with cochlear and retrocochlear auditory disorder. Speech intelligibility performance was analyzed in 15 patients with confirmed eighth-nerve disorder and in 15 patients with cochlear disorders, matched to the retrocochlear group for age and audiometric configuration, using confusion matrices derived from responses to a monosyllabic word list. Results indicated that: (1) vowel errors were more prevalent in the retrocochlear group and varied directly with increasing stimulus presentation level; and (2) consonant errors did not differ in type or relative frequency between the two groups, nor was there a level-dependent effect for consonant errors. These results are supported by the results of closed-set vowel identification tests and thus do not appear to be an artifact of open-set testing. Vowel errors may account for a major part of the speech 'rollover' phenomenon typical of retrocochlear auditory dysfunction.

Adult↗
PubMed1983

Susceptibility to intraspeech spread of masking in listeners with sensorineural hearing loss.

Previous research with speechlike signals has suggested that upward spread of masking from the first formant (F 1) may interfere with the identification of place of articulation information signaled by changes in the upper formants. This suggestion was tested by presenting two-formant stop consonant--vowel syllables varying along a/ba--/da/--/ga/ continuum to hearing-impaired listeners grouped according to etiological basis of the disorder. The syllables were presented monaurally at 80 dB and 100 dB SPL when formant amplitudes were equal and when F 1 amplitude was reduced by 6, 12, and 18 dB. Noise-on-tone masking patterns were also generated using narrow bands of noise at 80 and 100 dB SPL to assess the extent of upward spread of masking. Upward spread of masking could be demonstrated in both speech and nonspeech tasks, irrespective of the subject's age, audiometric configuration, or etiology of hearing impairment. Attenuation of F 1 had different effects on phonetic identification in different subject groups: While listeners with noise-induced hearing loss showed substantial improvement in identifying place of articulation, upward spread of masking did not consistently account for poor place identification in other types of sensorineural hearing impairment.

Adult↗
PubMed1983

Relationships among auditory brain stem responses, masking level differences and the acoustic reflex in multiple sclerosis.

We report the results of a study in which we compared auditory brain stem responses (ABR), the binaural masking level difference (MLD) for a 500-Hz pure tone and acoustic reflexes in 20 patients with confirmed multiple sclerosis. Our intent was to determine whether abnormalities in the three measures were related or whether they varied independently. The results indicated that the size of the MLD varied with the integrity of wave III of the ABR. When the ABR was abnormal to the extent of lacking wave III on one or both ears, there was no release from masking and the crossed acoustic reflex was abnormal, as well. The sensitivity of the MLD to retrocochlear disorder was comparable to that of ABR, and was greater than that provided by speech audiometry or acoustic reflexes.

Adult↗
PubMed1981

PB rollover and the acoustic reflex.

We present the results of a retrospective study of the speech understanding of 52 subjects with surgically confirmed acoustic neurinoma. Subjects were divided into three groups, depending on whether acoustic reflexes were all present, all absent, or present with abnormalities in the pathological ear. Results indicated that the three groups were homogeneous with respect to pure-tone sensitivity and PBmax. Subjects who lacked all acoustic reflexes, however, experienced significantly greater rollover of speech intelligibility at high intensities than did subjects with all or some reflexes intact. A neural-mechanical interaction is suggested as a basis for the rollover phenomenon in subjects with retrocochlear eight-nerve disorder.

Humans↗