Generate a sine wave
Download a WAV file holding a 1 kHz sine at -6 dBFS. A sine carries energy at one frequency and nowhere else, which is the property every other test signal is measured against.
One frequency, no harmonics
A square, triangle, or sawtooth wave is a sum of many sines. A sine is the one shape that is not, so anything else appearing in the output came from the equipment rather than the signal. That is what makes it the tool for finding distortion: feed a clean sine in, and any harmonic you measure on the way out is something the path added.
Where it gets used
- Setting and matching levels across a chain.
- Measuring total harmonic distortion, where the added harmonics are the whole result.
- Checking channel balance and phase between left and right.
- Confirming a converter or interface is passing audio at all.
Reading the level
The level control is peak, not RMS. A sine at -6 dBFS peak measures about -9 dBFS RMS, since a sine’s RMS sits 3 dB below its peak. Square waves are the exception, because their RMS equals their peak.
The edge fade
The file fades in and out over 10 ms. A tone that starts at full amplitude steps straight from silence, and a step contains every frequency, so it clicks. Ten milliseconds removes that without changing what the steady part of the tone measures.
Other shapes and frequencies
For a harmonic-rich signal use the square or sawtooth generator. To set frequency, level, duration, or sample rate yourself, use the full Tone Generator.