Acoustic reflex crossover artifacts in infants and young children.

Crossover artifacts occur when the probe microphone of an impedance instrument directly responds to vibratory-acoustic energy that crosses the skull from the stimulus transducer on the contralateral ear. The resulting meter deflections are subjectively similar to and may be interpreted as actual acoustic reflexes (ARs) by unsuspecting examiners. In this study, infants and young children aged 10 days to 6 years 9 months were fit with earplugs to eliminate the AR and were examined for artifact incidence and threshold. Results indicate a high rate of occurrence of the crossover artifact in the youngest subjects, when probe tones of 220 and 660 Hz were used with stimuli of 500 and 1,000 Hz. Artifact thresholds were found as low as at a 92-dB hearing level, and an inverse relationship was shown between age and artifact incidence and threshold.