Online tone generator

What a tone generator is actually for

Music is dozens of frequencies at once, which makes it useless for diagnosis — when something sounds wrong you cannot tell which part is at fault. A pure tone is one frequency and nothing else, so anything you hear that isn't that tone is a property of your equipment or your ears.

• Testing speakers. Rattles, buzzes and dropouts appear at specific frequencies. A sweep finds them; music hides them. Our sound test runs that sweep for you.
• Checking your hearing range. Raise the frequency until it disappears. Most adults lose the top of the range with age — see the table below.
• Tuning. 440 Hz is A4, the concert-pitch reference. The note name updates as you change pitch, so any note is a few keystrokes away.
• Masking tinnitus. Some people find a tone at or near the pitch of their tinnitus makes it less intrusive. This is symptom management, not treatment.
• Finding resonance. Sweep slowly near a rattling panel or cabinet and it will sing at its resonant frequency.

Which waveform to use

Waveform	What it contains	Use it for
Sine	One frequency, nothing else	Hearing tests, clean speaker testing, tuning
Square	Odd harmonics — bright and buzzy	Making faults audible; hearing the top of the range
Sawtooth	All harmonics — the richest	Filter and equalizer testing
Triangle	Odd harmonics, but soft	A gentler alternative to square

Because square and sawtooth carry more total energy than a sine at the same nominal level, they sound louder. Drop the level when you switch to them.

What lives where in the frequency range

Range	What it is
20–60 Hz	Sub-bass. Felt more than heard. Most speakers cannot produce it; phone speakers definitely cannot
60–250 Hz	Bass. Kick drums, bass lines, the warmth in a voice
250 Hz–2 kHz	Midrange. Most of the energy in speech and instruments
2–6 kHz	Presence. Consonants and attack — where intelligibility lives
6–20 kHz	Air and detail. The first range to go with age

If a low tone is inaudible on a phone, that is the speaker rather than your hearing. Phone drivers roll off steeply below roughly 300 Hz — which is also why bass boost does very little on a phone speaker and a great deal on headphones. The full explanation is in best EQ settings for bass.

On 432 Hz and 528 Hz

Both are here as presets, because a tone generator plays whatever frequency you ask for and these are among the most requested.

432 Hz is an alternative concert pitch, slightly lower than the 440 Hz standard most orchestras and instruments use. Some listeners prefer how it sounds, which is a legitimate preference. 528 Hz comes from a set of "solfeggio" frequencies that circulate widely online.

Claims that either frequency produces specific physical or biological effects are not supported by controlled evidence. We are not going to tell you otherwise to get the search traffic — play them, decide whether you like how they sound, and treat the rest with the scepticism you would apply anywhere else.

Listening safely

Sustained pure tones are more fatiguing than music at the same level, and high frequencies get uncomfortable faster. Start low and raise gradually. The usual guidance applies: sustained exposure above roughly 85 dB carries a hearing-damage risk, and iOS tracks your headphone exposure in the Health app. More on that in is a volume booster safe.