Browsing by Author "Brown, Deborah L."

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    Attachment and attributional styles in men and women with symptoms of attention-deficit/hyperactivity disorder
    (2003) Brown, Deborah L.; Kaplan, Bonnie J.
    Development of the auditory system can be investigated by using the cochlear traveling wave delay. Auditory brainstem response (ABR) and otoacoustic emissions (OAE) have been used to estimate this delay in order to' study the frequency dependent maturation of cochlear function in humans. Distortion Product Emissions (OPE) are a type of OAE. The OPE, unlike ABR, is a pre-neural measurement that does not include any synaptic component. Mean group delays can be estimated from the OPE phase-versusfrequency relationship (Kimberley et al., 1993). The present investigation used DPEs to estimate the round-trip travel time from 1.7 to IO kHz from 3 groups of neonates: 30-33 , 34-37, and 38-42 wks. conceptional age (CA); and an adult group. The results were consistent with the results from Kimberley et al. (1993) who found that as frequency increased round-trip travel time decreased. However, travel times in the youngest age group (30-33 wks. CA) were longer than for the older two infant groups (34-37 & 38-42 wks. CA). This difference may be attributable to changes or development in the middle ear. No significant differences in travel times were found between the 34-37 week CA infants and those of 38-42 week CA suggesting that some maturation is occurring up until 34 weeks CA. In comparison with the adults, the travel times from the two older newborn groups were not significantly different for either the high (7 & IO kHz) or low ( 1.7 & 2.4 kHz) f 2 frequencies, however in the mid-frequency range (3.5 & 5 kHz) the travel times were shorter in newborns. This difference in the mid-frequency range may be attributable to standing waves in the ear canal in the adults which could decrease the intensity of the primary tones used and therefore increase the latency of the travel time in that range (Dreisbach & Siegel, 1995). The similarities in the travel times at the high and low f2 frequencies suggest that the cochlea is adult-like by 34 weeks CA. This differs from the results of previous ABR studies which found that adult values were not reached until 3-6 months of age.