Biomedical subjects

Linda J Hood

Publications and source records attributed to Linda J Hood.

5 recordsLinked to original sources

PubMed2005

Absent or elevated middle ear muscle reflexes in the presence of normal otoacoustic emissions: a universal finding in 136 cases of auditory neuropathy/dys-synchrony.

We extracted a subpopulation of 136 patients (from our database of 257 AN/AD subjects) in whom middle ear muscle reflexes had been measured. None showed normal reflexes at all frequencies tested. Only three subjects showed any reflexes at 95 dB HL or below, but never at both 1 and 2 kHz in both ears whether ipsilaterally or contralaterally elicited. All the other reflex measures in these remaining 133 patients were either absent or observed above 100 dB HL, which is incongruous with their normal otoacoustic emissions throughout the frequency bands. Therefore, we urge colleagues to test ipsilateral middle ear muscle reflex at least at 1 kHz and 2 kHz in any perinatal hearing screening that depends solely on otoacoustic emissions. If the emissions are present and the reflexes are absent or elevated, an ABR may be required to properly intervene, because the management of AN/AD patients often differs drastically from what the behavioral audiogram or the ABR suggest.

Acoustic Impedance Tests↗

PubMed2004

Prevalence of central auditory processing (CAP) abnormality in an older Australian population: the Blue Mountains Hearing Study.

Age-related central auditory processing (CAP) abnormality has been described in many studies with widely varying prevalence reported. To date, there has been only one population study to report prevalence for this age-related condition, and these rates were significantly lower than in reports from clinical studies. The present study reports findings from a recent population study in which 2015 Australians aged 55 years and older living in a defined area west of Sydney were assessed with a battery of behavioral and electrophysiological auditory tests. This battery included speech measures from which a high overall prevalence rate (76.4%) of CAP abnormalities was found, in keeping with previous clinical studies. While gender differences were dependent on the test measure, the number of abnormal test outcomes increased systematically with age. Hearing loss and abnormal cognitive function, however, did not systematically increase with number of abnormal test outcomes.

Age Factors↗

PubMed2003

Auditory neuropathy/dyssynchrony: its diagnosis and management.

Patients with auditory neuropathy/dyssynchrony exhibit no auditory brain stem response (ABR), no middle ear muscle response, and both normal otoacoustic emissions or normal cochlear microphonics. An absent or grossly abnormal ABR is not always associated with deafness. In contrast, a hearing loss of 30 dB or more usually predicts absent otoacoustic emissions, but normal emissions can be seen in some patients whose behavioral audiograms imply total deafness. This article reviews the underlying physiology that makes these tests both useful and potentially misleading, and recommends steps to be considered by primary care physicians and other professionals to compensate for the vulnerabilities of each of the procedures.

Audiometry, Pure-Tone↗

PubMed2003

Patients with auditory neuropathy/dys-synchrony lack efferent suppression of transient evoked otoacoustic emissions.

Function of the olivocochlear reflex, measured by suppression of transient evoked otoacoustic emissions, is assessed in nine patients with bilateral auditory neuropathy/dys-synchrony and compared to matched control subjects with normal auditory function. TEOAEs were acquired using 65 dB peak sound pressure linear clicks with and without the presence of broad-band noise presented binaurally, ipsilaterally, or contralaterally in a forward masking paradigm. Efferent suppression differed significantly between subject groups (p < .0001). Mean suppression was less than 0.22 dB across all suppressor noise conditions for the auditory neuropathy/dys-synchrony subjects. TEOAE suppression averaged 4.47 (binaural), 2.41 (ipsilateral), and 1.52 (contralateral) dB in the control subjects. Suppression characteristics across the three suppressor conditions were also assessed in one patient with unilateral auditory neuropathy/dys-synchrony. The results suggest that poor efferent responses are related to compromised afferent input to the OCR pathway and support the use of efferent suppression of otoacoustic emissions as a differential measure of auditory function in patients with auditory neuropathy/dys-synchrony.

Acoustic Stimulation↗

PubMed2003

Olivocochlear efferent suppression in classical musicians.

Suppression of transient-evoked otoacoustic emissions was recorded from 29 members of the Louisiana Philharmonic Orchestra and 28 non-musician control subjects matched for age and gender. Binaural broad band noise was used as the suppressor stimulus in a forward masking paradigm. Results showed musicians to have significantly more suppression than non-musicians for both the right and left ears. Two possible explanations for this functional difference between groups are that moderately loud music serves as a sound conditioning stimulus and that music can be a mechanism for strengthening central auditory pathways which may influence the olivocochlear reflex arc. Possible explanations for this are discussed and ear, gender, and age differences within each group are examined. Additionally, middle-ear muscle reflex thresholds were found to be higher in musicians than non-musicians at some frequencies in some conditions.

Acoustic Impedance Tests↗