Any sound above 20 000 Hz is called ultrasound. It is too high pitched for humans to hear, but other animals (such as dogs, cats, dolphins and bats) can hear ultrasound. Ultrasound waves are ...

This experiment demonstrates how water affects sound waves and pitch. You'll discover how different water levels create different musical notes and learn about the relationship between mass, vibration ...

So sound waves move slower through it, which amplifies the lower frequencies in your voice. But here's the fascinating thing. The pitch of your voice hasn't changed when you inhale either gas ...