Development of auditory thresholds in young chickens

Absolute auditory thresholds were estimated in chickens within 12 h of birth and at 4 days after hatching. A two-interval, forced-choice staircase procedure was modified to use momentary suppressions in chick's peeping as indications of correct and incorrect responses. The estimated thresholds of both ages were the same at low frequencies (250–500 Hz). At higher frequencies (1–2 kHz), however, 4-day-old chicks had thresholds about 20 dB lower than the 0-day-old chicks. Thus absolute thresholds are a function of both frequency and age. These thresholds are likely to reflect perceptual development for two reasons: (a) Similar thresholds from both ages at low frequencies show that developmental differences are not due to differences in the sensitivity of the testing procedure; and (b) thresholds obtained from the 4-day-old birds are similar to other estimates from mature birds. In conclusion, responsiveness to low frequencies develops before responsiveness to higher frequencies. [Work supported by NIH.]