Short report : establishing normal hearing for infants with the auditory steady-state response26 Sep 2007
This study investigated the use of the dichotic multiple frequency ASSR technique for characterising normal hearing in a group of infants. A descriptive research design was implemented to describe ASSR thresholds obtained in 10 normal hearing infant ears (3 male, 2 female participants) between the age of 3 and 8 weeks. Normal hearing was controlled for by conducting a DPOAE screening test on all ears and ensuring no risk factors for hearing loss were present. Results indicated mean ASSR thresholds at 0.5, 1, 2, and 4 kHz to vary between 30 and 37 dB, ± 8 - 11 dB within a range of 20 – 50 dB HL. Eighteen percent of ASSR thresholds were obtained at 20 dB, 45% were obtained at 30 dB, and 38% were obtained at elevated levels of 40 and 50 dB. The recorded dichotic multiple frequency ASSR thresholds for infants with normal hearing were within the mild to moderate hearing loss range which makes differentiating between less severe degrees of hearing loss and normal hearing difficult. Until future research has been conducted, caution must be practiced when interpreting ASSR thresholds below 60 dB in young infants and additional techniques such as the ABR must be used to cross-check results.