The generator covers 20 Hz to 20 kHz, which is the range most people can hear; bass starts around 20–60 Hz and the upper limit falls with age, so many adults stop hearing tones above about 15–16 kHz. Because pitch is perceived logarithmically, the slider is log-scaled so low and high frequencies are equally easy to dial in, and you can also type an exact value (down to 0.01 Hz precision) or nudge by ±10 / ±100 Hz. The display shows the nearest equal-tempered note and how many cents sharp or flat the tone is, using the A4 = 440 Hz standard.

A sine wave is the simplest signal — one fundamental frequency with no harmonics — so it sounds smooth and flute-like and is ideal for clean reference and test tones. A square wave contains the fundamental plus odd harmonics, giving a hollow, reedy buzz. A triangle wave also has only odd harmonics but they fall off faster, so it sounds softer and sweeter than a square. A sawtooth wave contains every harmonic, odd and even, producing the brightest, most brass-like and buzzy tone. For pure frequency or hearing tests, use sine; the others are useful for synth-style tones and for hearing how harmonics change the timbre at the same pitch.

A frequency sweep plays a tone whose frequency changes smoothly from a start value to an end value over a chosen duration. AnyTool offers a logarithmic sweep, which spends equal time per octave and is the natural choice for full-range speaker and room checks, and a linear sweep, which spends equal time per hertz. Sweeping up through the bass helps you hear where a speaker or room rings or buzzes (resonances and rattles), and sweeping across the whole range gives a rough sense of which frequencies you can still hear. Set the start, end and time, choose log or linear, and press Play sweep — the tone glides while a progress readout tracks it.

You can use the generator to explore which frequencies you can hear, but it is not a substitute for a proper audiogram: the actual loudness reaching your ears depends on your device, headphones and volume setting, none of which are calibrated, so the result is not a clinical measurement. Treat it as a reference and a fun experiment, not a diagnosis. For safety, always start with a low volume and raise it slowly — sustained, loud or very high-frequency tones can harm your hearing, and loud low-frequency tones can damage speakers and headphones. You may not consciously hear ultrasonic-range tones even when they are loud, so trust the volume number rather than your ears, and stop if anything is uncomfortable.