Audio & Waveform Generator (with Metronome & Tuner)

This tool synthesises sound in real time with the browser’s Web Audio API, so no audio files are downloaded. The four waveforms differ in their harmonics. A sine wave contains a single frequency and sounds the purest, which makes it ideal as a tuning or hearing reference. A square wave contains only odd harmonics and sounds hollow, like early video games. A sawtooth contains every harmonic and sounds bright and buzzy, which is why synthesisers use it as a raw starting point. A triangle wave also has only odd harmonics, but they fade quickly (1/n²), so it sits between sine and square. The oscilloscope below draws the live waveform so you can see the shapes.

Frequency is adjustable from 20 to 2000 Hz. The default 440 Hz is concert pitch A4, the A above middle C. Doubling the frequency raises the pitch by one octave, so 220 Hz and 880 Hz are the A below and above. When testing speakers or headphones, sweep slowly upwards from the bottom: laptop and phone speakers usually cannot reproduce much below 100–200 Hz, so silence in the low range is often a physical limit of the driver, not a fault.

The metronome runs from 40 to 240 BPM (beats per minute), defaulting to 120. The interval between beats is 60 ÷ BPM seconds, so 60 BPM is one beat per second and 120 BPM is one every half second. For practice, learn a passage cleanly at a slow tempo, then raise it by 4–8 BPM at a time. Runners and rope skippers can use it to hold a steady cadence too.

Safety first: turn the volume down before pressing play, especially with headphones. Long exposure to high pure tones above 1 kHz can be uncomfortable, so stop immediately if you notice ringing or ear pain. The browser only starts audio after you press play, and every sound is generated locally on your device.