Skip to story
ELI5 Yahaaa

Counting wiggles

What Makes a Sound High or Low?

Fast vibrations sound high. Slow vibrations sound low. That is the whole of pitch.

Fast vibration High note — manywiggles a secondSlow vibration Low note — few wigglesa second
Pitch is just a counting rate.

  1. Step 1 of 5

    Sound comes from something vibrating.

    1 Somethingvibrates2 Air carries thepattern3 You hear apitch

    A string, a reed, a drum skin, your vocal cords. How fast it shakes decides what note you hear.

  2. Step 2 of 5

    Pitch is vibrations per second.

    High A — 880 Hz880 per secondMiddle A — 440 Hz440Low A — 110 Hz110

    That number is the frequency, measured in hertz. The A that orchestras tune to is 440 wiggles per second. Double it to 880 and you get the A an octave up.

  3. Step 3 of 5

    Short, tight and light vibrate faster.

    Long, loose, thick Slow — low noteShort, tight, thin Fast — high note

    Shorten a string, tighten it, or make it thinner and it flicks back and forth more quickly — so the note goes up.

  4. Step 4 of 5

    Every instrument uses the same three controls.

    1 Tighten theskin2 Shorten the aircolumn3 Thinner,lightermaterial

    A guitarist shortens the string with a finger. A violinist tightens with a peg. A piano uses long thick strings at one end and short thin ones at the other.

  5. Step 5 of 5

    Your ears have limits.

    Bat — up to 200,000 Hzfar beyond usDog — up to 45,000 Hzwhy whistlesworkHuman — up to 20,000 Hzand it dropswith age

    Humans hear roughly 20 to 20,000 Hz. Dogs hear far higher, which is how a silent dog whistle works, and elephants talk below what you can hear.

    The top of your hearing range falls as you get older — many adults cannot hear above 15,000 Hz.

The short version

Pitch is the vibration rate: more wiggles per second means a higher note.

Try it yourself

Fill glasses with different amounts of water and tap them. More water means slower vibration and a lower note.

Topics

Next tiny story