Author(s): Hongisto Valtteri, Oliva David
Environmental and building service appliance sounds involving tonal components can be more annoying than broad-band noise. Mandatory penalty values exist in many countries for tonal sound. The purpose of our study was to determine how tonal sounds are perceived compared to non-tonal sounds at overall level 25 dB LAeq, which is close to typical regulated levels inside residential dwellings. Forty participants rated the loudness and annoyance of 20 tonal sounds and 14 non-tonal reference sounds (19–45 dB LAeq) in laboratory conditions. The tonal frequencies were 50, 110, 290, 850, and 2100 Hz. Four levels of tonal audibility were used: 5, 10, 17, and 25 dB. The overall level of each tonal sound was 25 dB LAeq. Penalty was determined by determining the level difference with an equally annoying reference sound. The penalty depended on the tonal frequency and the tonal audibility. Annoyance penalty was zero or even negative at two lowest tonal frequencies 50 and 110 Hz. At other tonal frequencies, the penalty increased with increasing tonal audibility and tonal frequency. The largest penalty value, 12 dB, was obtained at tonal frequency 2100 Hz with the largest level of tonal audibility. Our results disagree with penalty values applied in many national regulations, when the overall level is low, 25 dB LAeq. A mathematical prediction model was developed which predicts the penalty as a function of tonal frequency and tonal audibility.
Name: Dr Valtteri Hongisto