Frequency and Pitch> Sounds come in different pitches. Some are high pitched, shrill, or sqeaky, while others are low pitched, deep, and resonating. Listen to a low pitched sound and you can almost feel the slow, steady beat of its vibrations.
The pitch of a sound comes from how fast its sound wave is vibrating. Pluck the lowest string on a six-foot-tall string bass. You will hear a low “thrummmm” of about 40 vibrations per second. Strike “middle C” on the piano and sing along. A pleasing duet at about 523 vibrations per second. The highest plink plink plink on the piano? 4,186 vibrations each and every second.
How quickly a wave vibrates is a property we call <#5653,5102><!frequency>. The more vibrations each second, the higher the frequency is, and the higher the pitch of the sound will be. The smaller a musical instrument is, the higher the frequencies of sound it will make. A ukulele looks like a toy guitar, and the sounds it makes are higher pitched than a full-sized guitar. A bass drum vibrates back and forth slowly, and makes a slow, booming sound, while the much smaller snare drum vibrates much faster, making sharp and crisp, higher-pitched sounds.
When we sound scientists talk about frequency, we use the term <#5654,5103><!Hertz>, abbreviated Hz, instead of “vibrations per second.” But they both mean the same thing. When you say that a sound has a frequency of 440 Hertz, you’re saying the sound wave vibrates 440 times a second.
And here’s an interesting thing I’ve noticed: when you double the frequency of a sound, you get a note that is a musical octave above your original note. You can use the synthesizer on this page to experiment for yourself.
