# Online tone generator Canonical page: https://soundtesters.com/tone-generator/ Generate pure reference tones from 1 Hz to 20,000 Hz. Switch waveforms, step by 1 Hz or full octaves, and route the signal to your left, right, or stereo output. ## How to use 1. Set your system and test volume low before starting playback. 2. Drag the frequency slider or enter an exact value from 1 Hz to 20,000 Hz. 3. Choose Sine, Square, Sawtooth, or Triangle waveform timbre. 4. Select Play tone or use the ±1 Hz and octave buttons to compare pitches. Pure sine waves contain only the fundamental frequency. Square and sawtooth waves add strong upper harmonics that sound much louder at the same gain. ## How to use the online tone generator Choose a target frequency using the slider, direct Hz number input, or quick reference presets such as 440 Hz (concert A4) or 1,000 Hz. Select Play tone for a ten-second reference signal or Short burst for a two-second check. Every tone uses a smooth envelope fade on startup and stop to prevent speaker clicks. You can also route the output to the left channel, right channel, or both stereo channels. ## Sine, square, sawtooth, and triangle waveforms explained A sine wave produces a smooth, single-frequency oscillation with no harmonic overtones, making it ideal for speaker checks, room-mode hunting, and pitch comparisons. Square and triangle waves add odd harmonics (3×, 5×, 7× the base frequency), while a sawtooth wave contains both even and odd harmonics. Because harmonic-rich waveforms carry energy at higher frequencies, they remain audible on small laptop speakers even when the fundamental bass frequency is below the speaker’s cutoff. ## Musical pitch and acoustic wavelength readouts As you change the frequency, the generator calculates the nearest equal-temperament musical note (referenced to A4 = 440 Hz) along with the cents offset. It also displays the physical acoustic wavelength in air based on a standard room speed of sound of 343 m/s (1,125 ft/s). A 60 Hz bass wave spans nearly 19 feet across a room, while a 10,000 Hz treble wave is just 1.35 inches long. ## Checking speakers, headphones, and room resonances Use low frequencies between 20 Hz and 200 Hz to listen for cabinet buzzes or desk vibrations, or switch to the dedicated [subwoofer bass test](https://soundtesters.com/subwoofer-bass-test/) for stepped 1/3-octave pads. If a tone sounds off-center or weak when both speakers play together, verify your wiring with the [speaker polarity test](https://soundtesters.com/speaker-polarity-test/). ## Frequently asked questions ### What frequency range does this tone generator cover? You can generate tones from 1 Hz up to 20,000 Hz in 1 Hz increments. Whether you hear the lowest bass or highest treble depends on your speakers or headphones, system sample rate, and personal hearing range. ### Why can I hear a 30 Hz square wave on phone speakers but not a 30 Hz sine wave? Small phone and laptop speakers cannot physically reproduce a pure 30 Hz fundamental sine wave. A 30 Hz square or sawtooth wave contains upper harmonics at 90 Hz, 150 Hz, 210 Hz, and higher, which small speakers can play. ### What is the difference between 432 Hz and 440 Hz? 440 Hz is the modern international standard for musical pitch A4 above middle C. 432 Hz is an alternative tuning reference sits about 31.8 cents flatter than standard A4. ### Does this tool upload or record any audio? No. All waveforms are synthesized locally inside your browser using the Web Audio API. No microphone permission is requested. ## Related tools - [Microphone test](https://soundtesters.com/microphone-test/) - [Speaker test](https://soundtesters.com/speaker-test/) - [Headphone test](https://soundtesters.com/headphone-test/) - [Surround sound test](https://soundtesters.com/surround-sound-test/) - [Tinnitus frequency finder](https://soundtesters.com/tinnitus-frequency-finder/) - [Hearing frequency test](https://soundtesters.com/hearing-frequency-test/) - [Subwoofer bass test](https://soundtesters.com/subwoofer-bass-test/) - [Speaker polarity test](https://soundtesters.com/speaker-polarity-test/)