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Development of low-frequency tone burst versus the click auditory brainstem response
Raymond M Hurley1, Annette Hurley, Charles I Berlin
1Department of Communication Sciences and Disorders, University of South Florida, Tampa, FL 33620-8150, USA. rhurley@chuma1.cas.usf.edu
Journal of the American Academy of Audiology
|April 6, 2005
Summary
Auditory Brainstem Response (ABR) testing reveals that hearing sensitivity in infants matures later than previously thought. Low-frequency tone burst responses and click-evoked responses do not stabilize by 70 weeks conceptional age.
Area of Science:
- Audiology
- Neuroscience
- Developmental Pediatrics
Background:
- Auditory Brainstem Response (ABR) testing is crucial for assessing infant hearing.
- Click stimuli assess high-frequency hearing, while tone bursts evaluate low-frequency sensitivity.
- Maturation data for low-frequency tone burst ABR is limited compared to click stimuli.
Purpose of the Study:
- To investigate the maturation of ABR latencies in response to low-frequency tone bursts and clicks in infants.
- To determine if auditory pathway maturation, assessed by ABR, stabilizes by 70 weeks conceptional age.
Main Methods:
- Tested 305 infants aged 33-74 weeks conceptional age.
- Measured absolute latencies of Wave V (click, 55/35/25 dB nHL) and Wave V500 (500 Hz tone burst).
Main Results:
- Latency for 500 Hz tone bursts significantly decreased with age, not stabilizing by 70 weeks CA.
- Click-evoked Wave III and V latencies also decreased with age, showing delayed maturation.
- Click-evoked Wave I latency was mature by 33 weeks CA.
Conclusions:
- Infant auditory system maturation, particularly for low-frequency hearing assessed by tone bursts, continues beyond 70 weeks conceptional age.
- Both click and tone burst ABRs indicate delayed maturation of central auditory pathways in infants.
- Wave I latency suggests early maturation of the auditory nerve for high frequencies.