- ultrasonic means a sound at frequencies higher than the human hearing range-over?.......
- why do you have to be careful when you listen to music with head phones?
- the sound waves hit the ear drum, a membrane at the end of the ear canal which?......
- only people under the age of 20 can hear sounds over 17,000 Hz (17 kilohertz or 17 kHz) How much sounds can and old person hear?.....
- the inside workings of a dogs' ears are actually a lot like humans'. However, dogs hearing is much more?......
