DecibelwerkQuick answer: The tone generator in Decibelwerk plays a clean test tone from 20 Hz to 20 kHz. Turn the big knurled knob to set the frequency on a log scale, fine-tune with the ÷2, −1, +1 and ×2 keys, pick sine, square, sawtooth or triangle, and press OUTPUT. It’s free. Pro adds a 20-second sweep from 20 Hz to 20 kHz.
The controls
- Tuning knob: 20 Hz to 20 kHz on a logarithmic scale, so the bass end isn’t cramped. The indicator lights amber while the tone plays.
- Screen: the frequency to two decimals below 1 kHz, the nearest musical note with cents (A4, C#5 +12¢), and a trace of the waveform.
- Waveform keys: SINE, SQUARE, SAW and TRI, each with its own LED.
- LEVEL knob and OUTPUT key. Starts and stops fade over a few milliseconds, so there are no clicks.
- SWEEP 20–20k (Pro): a logarithmic sweep across the whole range, for finding rattles and dead spots.
What people use it for
| Job | How |
|---|---|
| Test a speaker or headphones | Play a sine and sweep slowly; listen for buzzing or sudden drops. |
| Check your hearing range | Headphones, low level, raise the frequency until it disappears. |
| Tune an instrument | A4 = 440 Hz; the note readout shows how far off a pitch is in cents. |
| Find a room’s boomy spot | Play 40–120 Hz and walk the room. |
| Set levels | Play 1 kHz and read it with the sound level meter. |
Prefer the browser? The free online tone generator does the basics on any device.