Acoustic Self-Calibrating System for Indoor Smart Phone Tracking

Table 1

Difference between average hearing threshold and sound pressure level emitted by smart phones in units of the standard deviation.

Distance to smart phone	Smart phone type	18 kHz	20 kHz
1 cm	iPhone 4S	1.6	5.0
	Samsung GT-S5830	0.9	4.1
	iPod Touch	1.0	4.4
10 cm	iPhone 4S	1.9	6.4
	Samsung GT-S5830	1.8	4.1
	iPod Touch	1.7	4.1
5 m	iPhone 4S	3.5	11.7
	Samsung GT-S5830	3.4	12.0
	iPod Touch	3.5	11.3