Applying signal detection theory to determine the ringtone volume of a mobile phone under ambient noise

Although technologies for automatically adjusting the volume of mobile phone ringtones according to the ambient noise level have been developed, few studies have investigated the volume (dB) of the ringtone. This study suggested design recommendations for the ringtone volume under loud ambient noise. Based on signal detection theory, two-alternative forced-choice tracking was performed by thirty subjects to obtain hearing thresholds under noisy conditions. Six experimental conditions were examined: all combination of three pure tone frequencies (500 Hz, 1000 Hz, 4000 Hz) and two white noise levels (70 dB, 80 dB). The results showed that the ringtone volume should increase by 10-15 dB on average when the noise level increases from 70 dB to 80 dB. When adjusting the volume according to the ambient noise level, the volume should be changed differently according to the frequencies of a ringtone. The ringtone should be composed of low-frequency sounds under loud ambient noise because the subjects were very sensitive to the pure tone with frequency of 500 Hz. The results of this study could be used when developing design guidelines for the adaptive ringtone of a mobile phone. Moreover, designers can use this method to design other auditory signals such as notification and emergency alarms that have different chances of signal detectability. Relevance to industry: The results of this study may provide useful information to designers who consider the volume and frequency of a ringtone when adjusting ringtone volume according to ambient noise level. Moreover, the method used in the study could also be widely used to design auditory signals of mobile devices other than mobile phones. (C) 2015 Elsevier B.V. All rights reserved.