Auditory brainstem responses in the Eastern Screech Owl: An estimate of auditory thresholds

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between 1.5 and 6.4 kHz with the most acute sensitivity between 4–5.7 kHz. The shape of the average screech owl ABR audiogram is similar to the shape of the behaviorally measured audiogram of the barn owl, except at the highest frequencies. Our data also show differences in overall auditory sensitivity between the color morphs of screech owls

Auditory brainstem responses in the Eastern Screech Owl: An estimate of auditory thresholds

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between 1.5 and 6.4 kHz with the most acute sensitivity between 4–5.7 kHz. The shape of the average screech owl ABR audiogram is similar to the shape of the behaviorally measured audiogram of the barn owl, except at the highest frequencies. Our data also show differences in overall auditory sensitivity between the color morphs of screech owls

Auditory brainstem responses in the Eastern Screech Owl: An estimate of auditory thresholds

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between 1.5 and 6.4 kHz with the most acute sensitivity between 4–5.7 kHz. The shape of the average screech owl ABR audiogram is similar to the shape of the behaviorally measured audiogram of the barn owl, except at the highest frequencies. Our data also show differences in overall auditory sensitivity between the color morphs of screech owls

Auditory brainstem responses in the Eastern Screech Owl: An estimate of auditory thresholds

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between 1.5 and 6.4 kHz with the most acute sensitivity between 4–5.7 kHz. The shape of the average screech owl ABR audiogram is similar to the shape of the behaviorally measured audiogram of the barn owl, except at the highest frequencies. Our data also show differences in overall auditory sensitivity between the color morphs of screech owls

Auditory brainstem responses in adult budgerigars (Melopsittacus undulatus)

The auditory brainstem response (ABR) was recorded in adult budgerigars (Melopsittacus undulatus) in response to clicks and tones. The typical budgerigar ABR waveform showed two prominent peaks occurring within 4 ms of the stimulus onset. As sound-pressure levels increased, ABR peak latency decreased, and peak amplitude increased for all waves while interwave interval remained relatively constant. While ABR thresholds were about 30 dB higher than behavioral thresholds, the shape of the budgerigar audiogram derived from the ABR closely paralleled that of the behavioral audiogram. Based on the ABR, budgerigars hear best between 1000 and 5700 Hz with best sensitivity at 2860 Hz-the frequency corresponding to the peak frequency in budgerigar vocalizations. The latency of ABR peaks increased and amplitude decreased with increasing repetition rate. This rate-dependent latency increase is greater for wave 2 as indicated by the latency increase in the interwave interval. Generally, changes in the ABR to stimulation intensity, frequency, and repetition rate are comparable to what has been found in other vertebrates

Electrophysiological and morphological development of the inner ear in Belgian Waterslager canaries

Belgian Waterslager (BW) canaries have an inherited hearing loss due to missing and abnormal hair cells, but it is unclear whether the loss is congenital or developmental. We used auditory brainstem responses and scanning electron microscopy to describe the development of auditory sensitivity and hair cell abnormalities in BW and non-BW canaries. In both strains, adult ABR thresholds were higher than behavioral thresholds, but BW canaries exhibited higher thresholds than non-BW canaries across all frequencies. Immediately post-hatch, ABR thresholds and hair cell numbers were similar in both strains. Two weeks later, thresholds were significantly higher in BW canaries, and hair cell number progressively decreased as the birds aged. These data show that in BW canaries: the peripheral auditory system is functionally similar to non-BW canary from hatch to 2 weeks, ABR thresholds improve during this developmental period, actually becoming better than those of adults, but then worsen as the bird continues to age. Hair cell number and appearance is similar to non-BW canaries at hatch but progressively declines after 30 days of age. These data show that the hearing loss characteristic of BW canaries is, at least in part, developmental and is established by the time song learning begins

The auditory brainstem response in two lizard species

Although lizards have highly sensitive ears, it is difficult to condition them to sound, making standard psychophysical assays of hearing sensitivity impractical. This paper describes non-invasive measurements of the auditory brainstem response (ABR) in both Tokay geckos (Gekko gecko; nocturnal animals, known for their loud vocalizations) and the green anole (Anolis carolinensis, diurnal, non-vocal animals). Hearing sensitivity was measured in 5 geckos and 7 anoles. The lizards were sedated with isoflurane, and ABRs were measured at levels of 1 and 3% isoflurane. The typical ABR waveform in response to click stimulation showed one prominent and several smaller peaks occurring within 10 ms of the stimulus onset. ABRs to brief tone bursts revealed that geckos and anoles were most sensitive between 1.6–2 kHz and had similar hearing sensitivity up to about 5 kHz (thresholds typically 20–50 dB SPL). Above 5 kHz, however, anoles were more than 20 dB more sensitive than geckos and showed a wider range of sensitivity (1–7 kHz). Generally, thresholds from ABR audiograms were comparable to those of small birds. Best hearing sensitivity, however, extended over a larger frequency range in lizards than in most bird species