Development of tone-pip auditory brainstem responses and auditory steady-state responses in infants aged 0–6 months

Abstract

Conclusions: The longitudinal findings presented in this study suggest that with the maturational development, the conduction time of the auditory nerve decreases while the thresholds had no physiological changes within 0–6 months after birth. Comparing the tone-pip auditory brainstem response (ABR) with the auditory steady-state response (ASSR), the former had lower thresholds than the latter at 500–8000 Hz, which indicates that the estimation of tone-pip ABR maybe nearer to the actual hearing level of infants. Objective: To evaluate the feasibility of tone-pip ABR and ASSR for newborns and infants, and to follow the development of the threshold estimates from tone-pip ABR and ASSR in normal infants through the first 6 months of life. Methods: The tone-pip ABR and ASSR thresholds were measured at octave frequencies from 250 to 8000 Hz bilaterally in 80 infants aged 0–6 months with normal hearing. Results: For click ABR at 70 dB nHL, the absolute and inter-peak wave latencies decreased as the age increased. The tone-pip ABR had similar waveforms to the click ABR, its wave latencies decreased and the waveforms improved as the age and frequency increased. On average, the thresholds of tone-pip ABR and ASSR were observed at 1.2–41.2 dB nHL (SD = 2.6–8.0 dB) and 16.9–43.0 dB nHL (SD = 2.5–8.0 dB), respectively, at 250–8000 Hz in infants aged 0–6 months, but there were no physiological differences. Tone-pip ABR thresholds were significantly lower than those for ASSR except at 250 Hz (p < 0.05). Both ASSR and ABR had stable and similar audiograms in the different groups.

Keywords::

• Hearing
• maturation
• audiogram

Acknowledgments

This work was supported by a grant from the Science & Technology Division of Jinan (no. 20080114) and a grant from the Jinan Health Bureau (no. 2008-24).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.