【實用娛樂app】Dog Whistle|最夯免費app-綠色工廠好玩App

It use different sonic sounds of high frequency. Dogs can hear sound at higher frequencies than humans can. A dog whistle exploits this by emitting a high frequency sound to call to a dog. Many dog whistles emit sound in the upper audible range of humans, but some, such as the silent whistle, emit ultrasound at a frequency in the range 18–22 kHz.