Equal Annoyance Contours for Infrasonic Frequencies

Abstract

Eighteen subjects (age range: 18-25) rated the annoyance of 18 sound stimuli on a graphic scale (four infrasonic frequencies at different intensity levels and four levels of 1000Hz octave-ftltered pink noise for reference). The exposure time for each stimulus was 15 minutes. The order of exposures was determined from a latin square and each subject was exposed to only one stimulus per day. Equal annoyance contours were constructed to connect points that produced the same annoyance rating. The equal annoyance curves demonstrate that the lower the frequency the greater must be the sound pressure to cause a given amount of annoyance. Compared with 1000 Hz the curves lie much closer together in the infrasonic range. The closeness of the curves in the infrasonic region implies that small changes in sound pressure may cause relatively large changes in annoyance. Based on the experimental results a weighting curve with a slope of 12 dB per octave is suggested for the assessment of annoyance and loudness in the infrasonic range. A curve with the same slope and an attenuation of 0 dB at 10 Hz is at present under consideration in the International Standardization Organization. For environmental purposes a maximum permitted level of 95 dB is proposed for use with this curve.

Annoyance of Low Frequency Tones and Objective Evaluation Methods

“…This might indicate that the annoyance differs from loudness level at lower frequencies. This hypothesis is in agreement with the results from Andresen and Moller [7] that the annoyance level was higher than the loudness level at lower frequencies. Low frequency A-weighted sound pressure level vs. annoyance rating (PT: Pure tone; CT: Combined tones).…”

“…The results obtained in this study indicated that even a small change in sound pressure level above threshold could cause a relatively large change in the annoyance at lower frequencies. Similar results were obtained for frequencies of 31.5 Hz and below by Moller [6] and Adresen and Moller [7]. It was found in this study that a similar trend was observed at frequencies up to 80 Hz.…”

“…Loudness is closely related to the physical characteristics of the noise, [10] showed that the subjective responses of loudness and annoyance do not differ significantly for real sounds over a wide frequency range from 25 to 12000 Hz. Andresen and Moller [7] compared equal annoyance contours and equal loudness contours and concluded that the two sets of curves are remarkably similar in their general shape. However, they also mentioned that the annoyance level was higher than the loudness level at lower frequencies compared to their relation at 1000 Hz.…”

“…There have been various studies to measure the annoyance of low frequency sounds [4,[6][7][8]. Moller [6] and Andresen and Moller [7] obtained equal annoyance contours of pure tones for frequencies at 4,8,16, 31.5 and 1000 Hz. They measured the annoyance of these pure tones starting at a sound pressure level of about 15 dB above average hearing threshold defined in ISO 389-7 [5] frequencies, too.…”

Unpleasantness and Acceptable Limits of Low Frequency Sound

“…(2) given unpleasantness rating grade (y) was calculated by equation (2). The estimated equal unpleasantness contours were shown as four types of curves in Figure 3.…”