An Investigation into the Microstructure of the Low Frequency Auditory Threshold and of the Loudness Function in the near Threshold Region

The minimum audible field (MAF) is the sound pressure level at the threshold of audibility. The MAF threshold contour clearly demonstrates the variations in sensitivity of the auditory system with frequency. This frequency dependent sensitivity is also apparent at higher intensities, the importance of which is demonstrated by the extensive use of the dB(A) weighting in noise measurements. The sparse data available on low frequency auditory thresholds, and on the subjective effects of low level low frequency noise in the threshold region, indicated that a study of low frequency thresholds and near threshold equal loudness contours would fill a significant gap in the understanding of sound perception in this frequency range. This investigation demonstrates the existence of wide variations in individual sensitivity to low frequency sound. The diversity in auditory response to low frequencies between individuals should therefore be a prime consideration in low frequency noise control.