The effect of head movement and head positioning on sound field audiometry

Positioning and maintaining the subject's head at the calibration point (CP) of the sound field (SF) during SF assessment remains a challenge. The purpose of this study was to investigate the sound pressure level (SPL) at head positions likely to be encountered in routine audiological practice.

Eight National Health Service SF clinics were used to obtain SPL measurements. Part 1 of the study investigated SPL variability at positions around the CP (0.15 m and 0.30 m). Parts 2 and 3 of the study, investigated the SPL at two typical head heights of the infant population.

Only sound field measures were obtained.

Part 1: 32% and 40% of measurements of SPL around the CP were >2 dB different from the SPL at the CP (0.15 m and 0.30 m). Parts 2 and 3: 55% and 38% of measurements of SPL, at the two infant head heights, were >2 dB from the SPL at the CP.

Variability in SPL, due to head movement, is to be expected when performing SF audiometry. Furthermore, the typical head heights of infants will introduce additional variability, unless the position of the CP is chosen carefully.