Table 1.

Frequency Capabilities of Phone Hardware

DEVICE	FREQUENCY WHEN IDLE	FREQUENCY WHEN PLAYING MUSIC
Motorola Droid Mini	0–200 Hz	0–150 Hz
Samsung Galaxy Ace	0–120 Hz	0–80 Hz
ActiGraph GT3X	20–100 Hz	N/A

Even with load, phones can match dedicated devices. Both phones easily measure 10 Hz, the threshold of human walking. The Galaxy Ace is a last-generation midrange smartphone, used in the walk tests discussed. The Droid Mini is a current high-end smartphone, used in our current walk tests. The ActiGraph GT3X is an established standard monitoring device for medical evaluation of physical activity.

N/A, not applicable.