Psychophysical tuning curves for very low centre frequencies

Prediction and assessment of problems produced by low-frequency noise requires information about frequency selectivity in the low-frequency range. However, there are few data on frequency selectivity for centre frequencies below 100 Hz. To estimate the characteristics of auditory tuning for very low frequencies, psychophysical tuning curves (PTCs) were obtained for centre frequencies of 31.5, 40, and 50 Hz. An equal-loudness-level contour was also obtained using closely spaced frequencies. This was used as a rough estimate of the shape of the individual middle-ear transfer function in the frequency range below 100 Hz. Preliminary results on 1 subject are described. The PTCs showed distinct irregularities around the signal frequency, which may reflect the influence of beats. However, the overall shapes of the PTCs were broad, indicating that frequency selectivity at low frequencies is relatively poor.