Annoyance from and tolerance to sounds

Subjective measurements were performed on 40 normally hearing subjects to determine the annoyance caused by 10 sounds having distinctly different acoustical characteristics presented at sound pressure levels (SPLs) of 80, 90 and 100 dB. In addition, subjective measurements were obtained to estimate how long the subjects could tolerate performing a neutral, manual and mental task while being exposed to the 10 sounds at 80, 90 and 100-dB SPL, and determine which sounds were the most annoying and could be tolerated for the least amount of time while performing the neutral, manual and mental tasks. The measurements showed that the SPL was the most dominant factor in the perceived annoyance of the sounds examined and the time that they could be tolerated. The higher the SPLs, the greater the perceived annoyance and the less time each sound could be tolerated, regardless of the task. At a given SPL, however, some sounds were deemed more annoying and less tolerable than others. The sounds with multiple frequencies, frequency and/or amplitude changes and time varying patterns were deemed the most annoying and least tolerable. Conversely, the broadband, steady state sounds were deemed the least annoying and most easily tolerated. At a SPL of 100 dB, the subjects estimated they could tolerate sounds approximately 60% longer for performing a neutral task than for performing a manual task and approximately 40% longer for performing a manual task than for performing a mental task.