Bleep bleep!: determining smartphone locations by opportunistically recording notification sounds.

Every day, we carry our mobile phone in our pocket or bag. When arriving at work or to a meeting, we may display it on the table. Most of the time, we however do not change the ringtone volume based on the new phone location. This may result in embarrassing situations when the volume is too loud or missed calls and alarms when it is too low. In order to prevent such situations, we propose a non-intrusive opportunistic approach to determine the phone location and later adapt the ringtone accordingly. In our approach, we analyze the attenuation of the played ringtones to determine the nature of the surrounding elements. We evaluate our approach based on a prototypical implementation using different mobile phones and show that we are able to recognize the sole phone location with a precision of more than 94%. In a second step, we consider different surrounding environments and reach a precision of 89% for the phone position and 86% for the combination of the phone position and noise level of the environment, respectively.