Question
When performing ABR with tone burst stimuli for the purpose of hearing assessment in infants, should 8000 Hz be tested? I would think this would be useful for children who have been treated with potentially ototoxic medications.
Answer
The ABR can be elicited with high frequency tone burst stimulation at 8000 Hz and even much higher, assuming the earphones used have an adequate frequency response. It would be possible, for example, to stimulate an ABR for frequencies of 10000 or 12000 Hz with the right earphones.
For years, I've been asking ABR equipment manufacturers to offer high frequency stimuli and earphones as an option on their ABR systems for the very application you mentioned ... identification or documentation of ototoxic induced hearing loss in infants and young children. Nowadays I use the ASSR for threshold estimation at 8000 Hz in such patients, assuming they are quiet enough.
Before using 8000 Hz tone bursts with a typical ABR system you would want to first verify behavioral threshold with the stimuli. Most supra-aural earphones roll off in the high frequencies and insert earphones were designed to mimic the TDH supra-aural earphones. The maximum intensity level for insert earphones might be reduced for the 8000 Hz tone burst.
I think the 8000 Hz stimulus would be a good choice to use for newborn hearing screening because almost all infant hearing loss involves high frequencies, but at this point the click stimulus will probably not be abandoned for newborn hearing screening.
For an in-depth discussion of this topic, please view Dr. Hall’s recorded course on AudiologyOnline, Application of ABR in Objective Assessment of Infant Hearing
