a wave like vibration whether a sound as high or low depends on the frequency of the vibration frequency is measured in hertz one hertz equals one vibration percent and humans can hear a sound in the range between sixteen and twenty thousand hertz anything below sixteen hearts we call infrasound anything above twenty thousand hertz is all to a sound music is usually between fifty and eighteen thousand hertz it's impossible to individually measure the impulse response of so many sounds or frequencies that's why acoustic technicians divide them into sets encompassing eight notes. let's take this low c. for example as a starting point it has a frequency of one hundred thirty hertz. an octave higher is middle c. its frequency is exactly double that of the low c. two hundred sixty hertz after the same interval you come to the next c. which has a frequency of five hundred twenty hertz and so on the frequency doubles with every