The pure-tone thresholds of three mallard ducks were determined from 16 Hz to 9 kHz. The purpose was to determine whether the mallard duck hears infrasound, which then may potentially be used for navigation, similar to how it is proposed that pigeons use it for homing. At a level of 60 dB sound pressure level (re 20 μN/m2), their hearing range extends 6.85 octaves from 66 Hz to 7.6 kHz, with a best sensitivity of 12.5 dB at 2 kHz. However, at no frequency, including the lowest tested, were the ducks' thresholds lower than those of humans. Therefore, unlike pigeons and chickens, but like budgerigars, mallard ducks do not hear infrasound. Thus, the fact that a bird may fly long distances does not necessarily indicate that it hears infrasound.
Keywords: Audiogram; Avian hearing; Infrasound; Low-frequency sensitivity; Mallard duck.