The effect of high-pass filtering on TEOAE in 2-month-old infants

The aim of the present study was to investigate the effect of high-pass fil tering on TEOAE obtained from 2-month-old infants as a function of filter c ut-off frequency, activity states and pass/fail status of infants. Two expe riments were performed. In Experiment 1, 100 2-month-old infants (200 ears) in five activity states (asleep, awake but peaceful, sucking a pacifier, f eeding, restless) were tested by use of TEOAE technology. Five different fi lter conditions were applied to the TEOAE responses post hoc. The filter co nditions were set at 781 Hz (default setting), 1.0, 1.2, 1.4 and 1.6 kHz. R esults from this experiment showed that TEOAE parameters, such as whole-wav e reproducibility (WR) and signal-to-noise ratio (SNR) at 0.8 kHz and 1.6 k Hz, changed as a function of the cut-off frequency. The findings suggest th at the 1.6 kHz and 1.2 kHz filter conditions are optimal for WR and SNR pas s/fail criteria, respectively. Although all infant recordings appeared to b enefit from the filtering, infants in the noisy states seemed to benefit th e most. In Experiment 2, the high-pass filtering technique was applied to 2 3 infants (35 ears) who apparently failed the TEOAE tests on initial screen ing but were subsequently awarded a pass status based on the results from a follow-up auditory brainstem response (ABR) assessment. The findings showe d a significant decrease in noise contamination of the TEOAE with a corresp onding significant increase in WR. With high-pass filtering at 1.6 kHz, 21/ 35 ears could be reclassified into the pass category.