Laboratory study of the noticeability and annoyance of low signal-to-noise ratio sounds

The level of detectability of an acoustic signal that reliably attracts the attention of someone engaged in an activity other than specifically listening for such a sound is a quantity of practical interest in a number of field settings. Studies of the attention demand of sounds are of necessity conducted under laboratory conditions, however, because adequate control of signal presentation and listening conditions is not feasible in field settings. Subjects in the present study who were reading materials of their own choosing were asked in a free-response paradigm to note the occurrence of sounds presented at relatively low signal-to-noise-ratios in natural-sounding but highly constrained background noise environments. A logistic fit to the findings indicated that a detectability level approximately 7 dB greater than that needed for essentially perfect attentive detection was required to notice half of all signal presentations.