Short-latency auditory responses can be derived by cross-correlation of continuous pseudorandom noise stimuli with averaged scalp responses in both humans and experimental animals. Data are acquired very rapidly, and responses to specific spectral regions of the stimulus can be derived off-line. The method detects only frequency-following potentials and is most sensitive to low and middle frequencies. It is thus complementary to conventional auditory brainstem responses, which detect onset responses and are most sensitive to high stimulus frequencies. A series of studies in human subjects is proposed, withthe ultimate goal of developing a rapid and effective method for clinical assessment of auditory thresholds, i.e., audiogram estimation. Parametric studies will determine optimal ranges for stimulus/response duration and averaging time. Broadband masking, replicating previous studies in guinea pigs, will determine the contribution of cochlear microphonics in the earliest part of the response, while studies using deaf subjects will provide an estimate of stimulus artifact at high stimulus levels. High-pass masking studies will determine the extent to which basal cochlear loci contribute to responses to low frequencies. Low-pass masking will estimate the degree to which low-frequency stimulus components interfere with basally-generated responses to higher frequencies. Patients with low-frequency and high-frequency hearing loss will be tested to determine whether the thresholds for cross correlation functions in the corresponding spectral regions are appropriately elevated. The effects of sedation will also be studied. Finally, an objective method of threshold estimation using coherence functions will be compared to simple inspection of replicated cross-correlation functions. A protocol will be developed which can subsequently be tested in patients with hearing loss, and in sleeping or sedated children.
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| Dobie, R A; Wilson, M J (1991) Optimal smoothing of coherence estimates. Electroencephalogr Clin Neurophysiol 80:194-200 |
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| Tucci, D L; Wilson, M J; Dobie, R A (1990) Coherence analysis of scalp responses to amplitude-modulated tones. Acta Otolaryngol 109:195-201 |
| Dobie, R A; Wilson, M J (1989) Analysis of auditory evoked potentials by magnitude-squared coherence. Ear Hear 10:2-13 |
| Flint, P; Duckert, L G; Dobie, R A et al. (1988) Chronic perilymphatic fistula: experimental model in the guinea pig. Otolaryngol Head Neck Surg 99:380-8 |
| Dobie, R A; Wilson, M J (1988) Auditory responses to the envelopes of pseudorandom noise stimuli in humans. Hear Res 36:9-20 |
