How to use
- Turn the volume down first, then click Play.
- Drag the slider (a logarithmic scale from 20 Hz to 20 kHz), type a frequency or click a common one; − and + move by one semitone.
- Switch to Frequency sweep, set the start and end frequency and the duration to play a continuous rise (or fall).
Options explained
- Waveform
- A sine wave is a single pure frequency. Square and sawtooth waves are full of harmonics and sound louder and harsher; triangle is in between.
- Sweep
- Exponential, so each octave takes the same time and the pitch rises evenly. A sudden boost or buzz at one frequency usually means a resonance.
- Note
- Twelve-tone equal temperament with A4 = 440 Hz, with the offset in cents (100 cents = one semitone).
Frequencies and notes
Under the big frequency display the tool shows the nearest note and how many cents you are away from it, using equal temperament with A4 = 440 Hz. The note number is 69 + 12 × log₂(frequency ÷ 440), rounded to the nearest whole note. The Common frequencies buttons give these readings:
| Frequency | Nearest note |
|---|---|
| 50 Hz | G1, +35 cents |
| 100 Hz | G2, +35 cents |
| 440 Hz | A4, exactly |
| 1,000 Hz | B5, +21 cents |
| 4,000 Hz | B7, +21 cents |
| 8,000 Hz | B8, +21 cents |
| 12,000 Hz | F#9, +23 cents |
| 15,000 Hz | A#9, +10 cents |
| 17,000 Hz | C10, +26 cents |
Middle C is 261.63 Hz, and doubling a frequency raises it by exactly one octave (440 Hz to 880 Hz).
In Frequency sweep mode the pitch follows f = start × (end ÷ start)^t, where t runs from 0 to 1 over the Duration (s). The default 20 Hz to 20,000 Hz is a 1,000-fold range, almost exactly 10 octaves, so a 20-second sweep spends about 2 seconds per octave and reaches roughly 632 Hz at the halfway point (10 seconds). Duration can be set from 1 to 600 seconds.
Frequently asked questions
How high can people hear?
Young people usually hear up to 15–20 kHz; the upper limit drops with age and is often around 14 kHz by 40. Results also depend on your headphones, speakers and volume, so this is not a medical hearing test.
Why can't I hear low frequencies?
Phone and laptop speakers are too small to play much below about 100 Hz. Try headphones or speakers with a subwoofer.
Is it safe?
At low volume, yes. Do not play high frequencies or square waves loudly through headphones, and stop if it becomes uncomfortable.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.