The proportion of screened newborns was high, i.e. 98%. Multiple TEOAE recordings minimized the need for clinical ABR. Fifty-seven (0.18%) subjects showed bilateral hearing loss (exceeding ≈ 30 dB HL); median ABR threshold = 60 dB nHL (at 2.5 months of age). Bilateral and unilateral sensorineural hearing loss was found in 0.17% (n = 52; 56% males) and 0.06% (n = 18; 61% left ears, 56% males) of the screened newborns, respectively. Higher TEOAE pass percentages (p < 0.01) were demonstrated in right ears and in females than in left ears and males.

Transient-evoked otoacoustic emissions (TEOAEs) were recorded from more than 30000 newborns over a six year period. Analysis was performed on all the TEOAEs that passed the bedside universal hearing screen (n=60431), in order to characterize the normal properties of neonatal TEOAEs and to study ear and sex effects. Short recording times (median=33 s) were observed in combination with high entire TEOAE level (median=18.8 dB SPL for an 81.8 dB SPL peak stimulus), and high reproducibility (median=86%). Signal-to-noise ratio (S/N) of the TEOAE was highly frequency-dependent, being poorer at low frequencies. Prolonged averaging increased median reproducibility to 97%, but the minor S/N-improvement at low frequencies did not justify the longer test time. Highly significant mean lateral asymmetries (right >left) and sex differences (female >male) existed in entire TEOAE level, S/N TEOAE, and in half-octave frequency bands (700-4000 Hz). Mean lateral and sex entire TEOAE level differences were 1.1 dB and 1.3 dB, respectively. Stimulus levels were not affected by ear or sex. Hence, physiological differences at the level of organ of Corti were demonstrated in newborns.

Corneal-reflection eye-tracking provides an objective and fast assessment of horizontal SLA from about 6 months of age and may enable gaze to be used as an objective measure for sound localization in this age group. Infant SLA is immature and improvements are related to increasing age. Adults show high overall SLA and low intra- and intersubject variability in SLA. The technique may be used as a clinical tool for the evaluation of very early intervention in a young, preverbal population and throughout the life span.