Summary of: Ferm, I., Lightfoot, G., & Stevens, J. (2013). Comparison of ABR response amplitude, test time, and estimation of hearing threshold using frequency specific chirp and tone pip stimuli in newborns. International journal of audiology, 52(6), 419–423. https://doi.org/10.3109/14992027.2013.769280
This study evaluates the performance of the narrow-band CE-Chirp stimuli centred at 4 kHz and 1 kHz in a real-world clinical setting. The study was designed such that infants referred by the UK newborn hearing screen for ABR testing were first assessed using conventional tone burst stimuli at 4 kHz and 1 kHz, before repeating the procedure with the CE-Chirp stimuli. Key aspects of the performance were then compared i.e. response amplitude, Fmp (an objective indication of the likelihood of a response being present) and residual noise. The results from 42 infant ears showed that the mean ABR amplitudes to both 4 kHz and 1 kHz CE-Chirp stimuli, when compared to those from equivalent tone burst stimuli at the same level and comparable residual noises, were 64% greater. Fmp values for the CE-Chirp data were over twice as large as the corresponding tone burst data. Taken together these results indicate that CE-Chirp derived ABRs will offer significant time savings when testing infants, while the great Fmp values provide increased confidence in the presence of a response and this should translate into fewer “inconclusive” findings. Since the larger amplitude CE-Chirp responses will therefore lead to clear responses at lower levels than tone bursts, a more accurate estimation of the behavioural threshold is also proposed (i.e. an nHL-to-eHL correction factor that is 5 dB less for CE-Chirps than tone burst at 4 kHz and 1 kHz).
Related course: An Introduction to the CE-Chirp®