liminfoTone Generator
Free web tool: Tone Generator
Presets
Waveform Info
Sine
Pure tone, single frequency. Fundamental waveform.
Square
Rich in odd harmonics. Buzzy, hollow sound.
Sawtooth
Contains all harmonics. Bright, buzzy sound.
Triangle
Odd harmonics only, weaker. Soft, mellow sound.
About Tone Generator
The Tone Generator produces pure audio tones at any frequency between 20 Hz and 20 kHz — the full range of human hearing. Select from four waveform types (sine, square, sawtooth, triangle), set the exact frequency using a number input or slider, and adjust the volume before hitting Play. The tone plays continuously until you press Stop, making it useful for extended tests without having to hold a button.
Audio engineers use tone generators to test speakers, headphones, and room acoustics. The 440 Hz A4 preset is the standard tuning reference used worldwide, while sub-bass presets (20 Hz, 60 Hz) help verify that a speaker system can reproduce low frequencies. The presence (4 kHz) and air (15 kHz) presets help identify problems in the high-frequency response of audio equipment. Musicians can use the sine wave to tune instruments by ear against a pure reference pitch.
Under the hood, the tool uses the Web Audio API's OscillatorNode connected to a GainNode. The oscillator type maps directly to the four standard waveform types defined in the Web Audio API specification. Crucially, frequency and volume can be updated in real time while the tone is playing — the frequency value and gain value are updated on the existing nodes without stopping and restarting, ensuring a smooth transition. All audio is generated algorithmically in your browser; no audio files are downloaded.
Key Features
- Generates continuous audio tones from 20 Hz to 20 kHz
- Four waveform types: sine (pure), square (buzzy), sawtooth (bright), triangle (soft)
- Precise frequency input via number field and range slider
- Volume control from 0% to 100% via slider
- Live frequency and volume update while tone is playing
- 8 frequency presets from sub-bass (20 Hz) to air (15 kHz)
- Waveform description panel explaining the harmonic character of each wave
- 100% Web Audio API — no audio files downloaded, no server needed
Frequently Asked Questions
What is the Tone Generator?
It is a free browser-based tool that generates audio tones using the Web Audio API. You choose a frequency, waveform type, and volume, then click Play to hear the tone. It is useful for audio testing, instrument tuning, hearing tests, and sound experiments.
What is the difference between sine, square, sawtooth, and triangle waves?
A sine wave produces a pure tone with a single frequency — the most basic waveform. A square wave adds rich odd harmonics, creating a buzzy or hollow sound. A sawtooth wave includes all harmonics (both odd and even), producing a bright, aggressive sound. A triangle wave contains only odd harmonics like the square wave, but they decay faster, creating a softer, mellower sound.
What frequency should I use for audio equipment testing?
Common test frequencies include 1 kHz (mid-range reference), 440 Hz (A4, standard musical tuning), 20 Hz (sub-bass, tests woofer capability), 10 kHz (treble), and 15 kHz (air, tests tweeter and hearing acuity). The tool provides all of these as preset buttons.
Can I change the frequency while the tone is playing?
Yes. You can move the frequency slider or type a new value in the number field while the tone is playing. The frequency updates immediately without any interruption or clicking sound, because the tool directly updates the oscillator frequency parameter in real time.
What is the 440 Hz preset for?
440 Hz corresponds to the musical note A4 — the A above middle C on a piano. It is the international standard tuning reference used by musicians and instrument makers worldwide. Playing a 440 Hz sine wave lets you tune instruments like guitar strings by listening for beats (interference) as you tighten or loosen the string.
Can I use this to test my hearing?
Yes, in a general sense. You can sweep through frequencies to identify the upper and lower limits of what you can hear. Note that this is not a calibrated clinical audiogram — professional hearing tests require calibrated equipment and controlled conditions. But for a quick informal check, it works well.
Why does the tone sound harsh at high volumes?
Square and sawtooth waves contain many harmonics and can sound harsh even at moderate volumes. Try using a sine wave for a cleaner, smoother tone, especially for speaker testing where you want to isolate specific frequencies without adding harmonic distortion.
Does this work offline?
Once the page is loaded in your browser, the tone generator works without an internet connection. The Web Audio API generates sound entirely within the browser using your device's audio hardware — no server communication is needed to produce tones.