What is a sine wave tone used for?

A sine wave produces the purest possible tone — a single frequency with no harmonics. It is used as a reference tone for tuning instruments (440 Hz = concert A), calibrating audio equipment, conducting hearing tests, and testing speaker frequency response. Because it contains no harmonics, any distortion or resonance is immediately apparent.

What is the difference between sine, square, sawtooth, and triangle waveforms?

A sine wave contains only the fundamental frequency — pure and smooth. A square wave contains the fundamental plus all odd harmonics (3rd, 5th, 7th...) — bright and buzzy, like a clarinet. A sawtooth wave contains all harmonics (odd and even) — very bright and brash, like a violin bow. A triangle wave has odd harmonics that fall off faster — softer than square, resembling a flute.

Can I use this as a hearing test?

Yes. Play tones at different frequencies to check your hearing range. Human hearing spans roughly 20 Hz to 20,000 Hz, though the upper limit decreases with age — many adults over 40 cannot hear above 14,000–16,000 Hz. Use headphones for best results, keep the volume low, and start at mid-frequencies before testing the extremes. This is not a medical test — consult an audiologist for clinical hearing assessment.

Tone Generator | CodeLint.Dev

The four waveforms

Wave	Harmonic content	Sounds like	Used for
Sine	Fundamental only	Pure, hollow, flute-like	Frequency response tests, hearing tests, reference tones
Triangle	Odd harmonics, falling steeply	Soft, slightly reedy	Mellow synth tones, sub bass
Square	Odd harmonics, falling gently	Hollow, buzzy, clarinet-like	Chiptune, testing amplifier clipping
Sawtooth	All harmonics	Bright, buzzy, brass-like	Classic subtractive synthesis, the richest raw source

A sine wave is the only one with no harmonics — it is a single frequency by definition. Every other waveform is a sum of sines, which is Fourier’s result and the basis of all spectral analysis.

Useful test frequencies

Frequency	What it tests
20–30 Hz	Subwoofer extension. Most speakers produce nothing usable here — if you feel rather than hear it, that is correct
60 Hz / 50 Hz	Mains hum. If you hear this in a recording, it is electrical interference — 60 Hz in the Americas, 50 Hz elsewhere
100–200 Hz	Room modes. Walk around the room: large volume changes indicate standing waves
440 Hz	A4, the standard tuning reference
1 kHz	The reference frequency for most audio measurements and level calibration
3–4 kHz	Peak human sensitivity. Also where sibilance and listening fatigue live
8–12 kHz	Presence and air. Age-related hearing loss shows here first
15–20 kHz	Upper limit. Most adults over 40 hear little above 15 kHz, and that is normal

About

The Tone Generator produces pure audio tones using the Web Audio API. Choose from sine, square, sawtooth, and triangle waveforms at any frequency between 20 Hz and 20 kHz. It is useful for hearing tests, tinnitus masking, speaker testing, music tuning (440 Hz reference tone), and audio engineering experiments.

How to use

1 Use the slider or type an exact value to set the frequency.
2 Select a waveform: Sine (pure tone), Square (buzzy), Sawtooth (bright), or Triangle (soft).
3 Adjust the volume slider and toggle the mute button as needed.
4 Press the Play button to start the tone. Press Stop to silence it.
5 Use the preset buttons to jump to common test frequencies.

What is a sine wave tone used for?: A sine wave produces the purest possible tone — a single frequency with no harmonics. It is used as a reference tone for tuning instruments (440 Hz = concert A), calibrating audio equipment, conducting hearing tests, and testing speaker frequency response. Because it contains no harmonics, any distortion or resonance is immediately apparent.
What is the difference between sine, square, sawtooth, and triangle waveforms?: A sine wave contains only the fundamental frequency — pure and smooth. A square wave contains the fundamental plus all odd harmonics (3rd, 5th, 7th...) — bright and buzzy, like a clarinet. A sawtooth wave contains all harmonics (odd and even) — very bright and brash, like a violin bow. A triangle wave has odd harmonics that fall off faster — softer than square, resembling a flute.
Can I use this as a hearing test?: Yes. Play tones at different frequencies to check your hearing range. Human hearing spans roughly 20 Hz to 20,000 Hz, though the upper limit decreases with age — many adults over 40 cannot hear above 14,000–16,000 Hz. Use headphones for best results, keep the volume low, and start at mid-frequencies before testing the extremes. This is not a medical test — consult an audiologist for clinical hearing assessment.

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