Online Tone Generator

What this sound frequency generator does

As a sine wave generator, it plays a single tone at any frequency from 20 Hz to 20 kHz — the range usually quoted for human hearing. The number box, the slider and the octave buttons all move the same tone, and changes glide smoothly while it plays, so you can sweep by hand without clicks.

The slider is logarithmic: each octave takes the same distance, which is how pitch actually feels. 20 to 40 Hz is as much travel as 10 to 20 kHz.

Sine, square, sawtooth or triangle?

Square and sawtooth contain much more energy than a sine at the same peak, so this tool turns them down automatically. If one still sounds harsh, lower the volume — harmonics land in the 2–5 kHz range where ears are most sensitive.

Frequencies worth knowing

• 50 Hz and 60 Hz — mains-power hum. If you hear a hum from an amplifier or a recording, play both and see which one matches.
• 100–200 Hz — where phone and laptop speakers start to give out. Listen for buzzing here.
• 440 Hz tone — the note A4, the standard tuning pitch. The readout shows the nearest note and how far off it is in cents for any frequency.
• 1 kHz — the standard reference tone for setting levels and checking that left and right match.
• 8–17 kHz — the top end, where hearing loss from age and noise exposure shows first.

Test tone checks you can run

1. Left and right. Play 1 kHz on Left, then Right. Both should be the same loudness from the same place.
2. Rattles. Play 80–200 Hz and slowly drag the slider. A buzz at one spot is a loose part or object — touch things until it stops.
3. Hearing range. On headphones at a low level, step up from 8 kHz. Note where the tone disappears; compare ears with Left and Right.
4. Tuning. Play 440 Hz and tune the A string to it, or type any note’s frequency.

Using tones safely

Start quiet. A pure tone sounds less loud than music at the same level, and high tones are tiring well before they feel painful. Keep long sessions at a moderate volume, and don’t push small speakers hard with low frequencies or square waves for minutes at a time — that is how they overheat.