Walsh, J.K.  and Dooling, R.J. (1974). Auditory evoked responses recorded from the skull in unanesthetized parakeets (Melopsittacus undulatus). J. Acoust. Soc. Am. 56, S63.

Average auditory evoked responses were collected from the skulls of awake, unrestrained parakeets. Evoked responses were collected at eight intensities of a 1000-Hz tone. The waveform of the evoked response was highly consistent across birds, with a major positive deflection occurring at 20–30 msec after tone onset followed by a negative deflection at about 35–45 msec and a second positive deflection at 100–120 msec. Over the intensity range examined, the size of the evoked response is linearly related to the intensity of the stimulating tone. The slopes of these functions show a zero crossing between 5–15 dB which compares favorably to the behaviorally determined threshold at 1000 Hz for this species.