Changes in Middle-ear Input Admittance During Postnatal Auditory Development in Chicks

Admittance at the tympanic membrane was measured in one ear of 73 chicks in 8 age groups between 1 and 150 days post-hatch. Admittance at 7 frequencies (0.66-1.8 kHz) was calculated from measurements of the magnitude and phase angle of sound pressure in front of the tympanic membrane. The results show that admittance magnitude at all frequencies increased exponentially with age during the first 70 days of life. The admittance angle also changed systematically with age. These developmental events may be related to changes in the compliance and resistance of the tympanic membrane.