Audiograms of three subterranean rodent species (gen. Fukomys) determined by auditory brainstem responses reveal extremely low high-frequency cut-offs

Abstract

Life underground has shaped the auditory sense of subterranean mammals, shifting their hearing range to low frequencies. Mole-rats of the genus Fukomys have, however, been suggested to hear up to 18.5 kHz, unusually high for a subterranean rodent. We present audiograms of three mole-rat species, Fukomys anselli, Fukomys micklemi and the giant mole-rat Fukomys mechowii, based on evoked auditory brainstem potentials. All species showed low sensitivity and restricted hearing ranges at 60 dB SPL extending from 125 Hz to 4 kHz (5 octaves) with most sensitive hearing between 0.8 kHz and 1.4 kHz. The high frequency cut-offs are the lowest found in mammals to date. In contrast to predictions from middle ear morphology, F. mechowii did not show higher sensitivity in the low frequency range than F. anselli. These data suggest that the hearing range of Fukomys mole-rats is highly restricted to low frequencies and similar to other subterranean mammals.