+ The Decibel Scale All decibel measurements are not completely accurate, they are related to our perception by the human ear. A sound measuring 0 Db is can barely be heard by the ear. We measure variations on the scale by a factor of 10.
+ A Sample of a Decibel Scale Another one can be found on p. 103 of your textbook.
+ Pitch and Frequency Lower Pitch = lower frequency sound. High Pitch = Higher frequency sound.
+ Infrasound and Ultrasounds Infrasounds = sounds under 20Hz Used by some animals to communicate. E.g. Elephants Ultrasounds = sounds above 20 000 Hz Used in medical imaging Used by some animals like bats (echolocation)