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Spectrogram

see sound · spectrum analyzer

Silence — choose a source

Sound is air vibrating — hundreds or thousands of times per second. Here you can see it: as a wave on an oscilloscope, as a frequency spectrum and as a spectrogram — the “sheet music” that sound draws by itself. Whistle, sing, play your favorite song or turn on the generator — everything is computed live, in your browser.

Main view

Sound will appear hereChoose a source: microphone, file or generator.
Hover over the plot (or click it and use the arrow keys) to measure frequency and level.

Controls

Everything you hear passes through a limiter, which clips sudden jumps in loudness.

Sound source

Waveform
A4
Shortcut: G
Wearing headphones? Start at a low volume (20% by default) and turn it up slowly. Pure tones sound louder in headphones than from speakers.

Tuner

YIN · ±50 ct
—
Freq.—
Offset—
Clarity—
Waiting for a clear tone…

Oscilloscope

preview

What are you seeing?

Timbre — what makes a flute differ from a clarinet playing the same note: a different set and strength of harmonics.
Decibels are logarithmic: +10 dB means 10 times more power, +20 dB — 100 times.
The human hearing range is about 20 Hz – 20 kHz; the upper limit drops with age.

Challenges

0 / 3

  1. Whistle the note A4 (440 Hz) to within ±10 cents

    Turn on the microphone and whistle (or sing) so that the tuner shows A4 and the needle stays within ±10 ct for 1 second. Hint: the generator with a 440 Hz tone will show you what this note sounds like.

    Requires a microphone.
    Well done! You have an ear like a tuning fork.

  2. Sing the vowel “i”, then “a”

    Sing a long “iiii” (as in “see”) into the microphone, then “aaaa” (as in “father”), at the same pitch. Watch the spectrogram: with “i” a bright band appears high up (the second formant, ~2.3 kHz), while with “a” the energy gathers around 0.7–1.2 kHz.

    Requires a microphone.
    Great! You've just seen formants — that's how your voice “draws” vowels.

  3. Hearing test: find the highest sound you can hear

    The generator will play a quiet tone that slowly climbs — from 4 kHz all the way to 20 kHz. Press “I can't hear it” when it disappears.

    Well done!

Did you know…?

  1. A clarinet “jumps” by a twelfth, not an octave. It behaves like a pipe closed at one end, so in its low register the even harmonics are very weak. When overblown, a flute goes up an octave, while a clarinet goes up an octave and a fifth.
  2. Elephants talk in infrasound (below 20 Hz), which can carry for several kilometers, and bats hunt by sending out ultrasound of over 100 kHz. Both ranges are completely inaudible to us.
  3. A sound 10 dB louder carries 10 times more energy, yet the ear perceives it as only about twice as loud. That's why decibels are logarithmic — just like our hearing.