Tone Generator

How Does the Tone Generator Work?

The Tone Generator uses the Web Audio API's OscillatorNode to produce continuous audio signals at precise frequencies. When you click "Play Tone," the tool creates an AudioContext, instantiates an oscillator node set to your chosen frequency and waveform type, and connects it through a GainNode that controls volume. The oscillator generates a mathematically perfect periodic waveform that repeats at the specified number of cycles per second (Hertz). A 440 Hz sine wave, for example, completes exactly 440 full cycles every second, producing the A4 note used as the universal tuning standard.

The four available waveform types each have distinct characteristics. A sine wave is the purest tone with no harmonics — it contains only the fundamental frequency. A square wave contains the fundamental plus all odd harmonics (3rd, 5th, 7th, etc.), producing a hollow, buzzy sound. A sawtooth wave contains all harmonics (both odd and even) at decreasing amplitudes, creating a bright, rich tone. A triangle wave contains only odd harmonics like the square wave, but at much lower amplitudes (falling off as 1/n squared), resulting in a softer, flute-like quality.

Understanding Frequency and Human Hearing

Frequency, measured in Hertz (Hz), determines the pitch of a sound. The human hearing range spans approximately 20 Hz to 20,000 Hz (20 kHz), though this range narrows with age. Most adults over 25 cannot hear frequencies above 15,000 Hz, and by age 50, the upper limit often drops to around 12,000 Hz. This age-related hearing loss (presbycusis) primarily affects higher frequencies. You can use this tone generator to test your personal hearing range by gradually increasing the frequency until you can no longer hear the tone.

Musical notes correspond to specific frequencies defined by the equal temperament tuning system. The standard reference pitch is A4 = 440 Hz, adopted internationally in 1955. From this reference, every note is spaced by a ratio of the twelfth root of 2 (approximately 1.05946). This means each octave doubles in frequency: A3 is 220 Hz, A4 is 440 Hz, and A5 is 880 Hz. Middle C (C4) is 261.63 Hz, and the lowest note on a standard piano (A0) is 27.5 Hz.

Speaker and Headphone Testing

This tone generator is valuable for testing audio equipment. Sweep through the frequency range from low to high to check if your speakers or headphones reproduce all frequencies evenly. Small speakers and earbuds often struggle with frequencies below 100 Hz, while damaged tweeters may fail to reproduce high frequencies above 10,000 Hz. Listen for rattling or buzzing at specific frequencies, which can indicate loose components, damaged drivers, or resonance issues in your speaker enclosure. A clean sine wave should sound smooth and pure at all volumes — any distortion indicates a problem.

Tinnitus Frequency Matching

People experiencing tinnitus (ringing in the ears) can use the tone generator to identify the frequency that matches their tinnitus tone. Start at a low frequency and slowly increase until the generated tone matches what you hear. Common tinnitus frequencies range from 2,000 Hz to 8,000 Hz. Knowing your tinnitus frequency can be helpful when discussing treatment options with an audiologist, as some sound therapy approaches use the specific tinnitus frequency for notched sound therapy or tinnitus retraining therapy (TRT).

Audio Equipment Calibration

Sound engineers use tone generators for calibrating audio systems, testing signal chains, and setting reference levels. The 1,000 Hz sine wave is the standard calibration frequency used to set unity gain across audio equipment. When setting up a PA system, monitor speakers, or recording chain, a 1 kHz tone at a known level helps ensure consistent gain staging from input to output. The quick-select buttons below include this standard calibration frequency for convenient access.