Generate a square wave
Download a WAV file holding a 1 kHz square wave at -6 dBFS. Unlike a sine, a square carries a long series of harmonics, which is what makes it useful for hearing and seeing what a system does to them.
Odd harmonics, falling as 1/n
A square wave is the sum of its fundamental plus every odd harmonic, each at 1/n amplitude. A 1 kHz square holds energy at 3 kHz at a third the level, 5 kHz at a fifth, 7 kHz at a seventh, and so on upward. There are no even harmonics.
That structure is why a square makes filters obvious. Roll off the top and the edges visibly round; the harmonics you removed were what made them sharp.
Band limits and ringing
A true square needs infinite bandwidth. At 48 kHz the Nyquist limit is 24 kHz, so the series stops at the 23rd harmonic of a 1 kHz tone. Summing a truncated series overshoots at every transition, which shows as ripple on the flat sections. That is the sample rate showing through, not a defect in the file.
What it suits
- Hearing a low-pass or high-pass filter act on real harmonic content.
- Checking slew rate and transient behaviour in an amplifier or converter.
- Driving a clipper, wavefolder, or distortion stage with a known harmonic set.
Level compared with a sine
A square’s RMS equals its peak. A sine’s RMS sits 3 dB below its peak. Both files here peak at -6 dBFS, so the square measures and sounds noticeably hotter. Drop the level before sending one into a monitor path.
Other shapes
A sawtooth carries both odd and even harmonics; a triangle carries odd ones that fall far faster. To set frequency, level, or duration yourself, use the full Tone Generator.