Effects of altered prenatal auditory experience on postnatal auditory preferences in bobwhite quail chicks

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Virginia Tech


Part I of the present study analyzed the acoustic features of bobwhite quail embryonic vocalizations emitted during the final 36 hours prior to hatching. Using software for sound spectrographic analyses, information was collected on the average fundamental frequency, frequency modulation and range, repetition rate, and duration in seconds of notes emitted by the embryos. Based on frequency distributions plotted separately for three of these acoustic features, the vocalizations emitted spontaneously by bobwhite quail embryos were characterized. Although there were not two dichotomous note types to justify adopting the "distress/contentment" terminology utilized by previous researchers of avian vocalizations, there was a distinctive note type with medium note duration and fast repetition rate, as well as a second common note type with short note duration and fast repetition rate.

Evidence from precocial neonates of several species indicates that altering the usual prenatal sound environment alters later perceptual performance. Part II of the present study examined the influence of altered prenatal auditory stimulation (in the form of embryonic vocalizations altered in repetition rate) on postnatal auditory preferences in precocial bobwhite quail chicks. Results indicate that when embryos are exposed to altered prenatal auditory stimulation in the period immediately prior to hatching, their postnatal auditory preference behavior is altered. Specifically, when exposed to a repetition rate that is (only slightly) faster than the species-typical rate for embryos, quail hatchlings did not show a strong preference for the maternal call typically seen at 24 hr post-hatch. Chicks that were exposed prenatally to either unaltered auditory stimulation or auditory stimulation with a slower-than-normal repetition rate did demonstrate the species-typical naive auditory preference. These findings illustrate the importance of understanding the subtle experiential links between the prenatal sensory environment and early postnatal perceptually-directed behavior.