Comparing auditory brainstem responses (ABRs) to toneburst and narrow band CE-chirp in young infants.

Objective: The difference of characteristics (latency and amplitude) between toneburst and narrow CE-chirp stimuli on ABR recording was analyzed in normal hearing infants.

Methods: 500, 1000, 2000 and 4000 Hz toneburst and narrow band CE-chirp auditory brainstem responses (ABRs) were recorded in 40 normal-hearing infants. The amplitude and latency parameters of the ABR were collected for each of the four stimulus levels: 80, 60, 40, and 20 dB nHL. Both stimuli started from 80 dB nHL using alternating polarity and the rates were both 27.1/s.

Results: The toneburst latencies are greater than narrow band CE-chirp latencies for all intensities at 500, 1000 and 2000 Hz (p < 0.001). However, at 4000 Hz this difference was not significant. At 500 Hz, wave V amplitude is larger for toneburst than narrow CE-chirp (p < 0.001) in 80 dB nHL. The difference between the two stimuli in 60 dB nHL was not significant (p = 0.495) and at 40 and 20 dB nHL the wave V narrow band CE-chirp amplitude is greater than toneburst amplitude (p < 0.001). At 1000, 2000 and 4000 Hz there is no difference between the wave V toneburst and narrow band CE-chirp amplitudes at 80 dB nHL (p = 0.940; p = 0.776 and p = 0.217 respectively). On the other hand, in the levels to 60, 40 and 20 dB nHL, narrow band CE-chirp amplitudes are larger than toneburst amplitude (p < 0.001).

Conclusion: Narrow band CE-chirp ABRs generates shorter latencies than the toneburst ABRs, especially to low frequencies. Higher amplitudes were found with narrow band CE-chirp stimuli for all frequencies tested, except to high levels.