Generators · attention signals
Alarm Generator
Build the tones that wake people up: single beeps, double beeps, sirens, urgent warbles, a stutter pulse train or a plain continuous tone. Pick a pattern, set the pitch and tempo, and the browser schedules every pulse precisely on the audio clock. Save the result as a WAV file.
This is a test signal, not certified alarm equipment. Alarms are loud by design - start with the level low and wear headphones at a distance when experimenting. Nothing here is rated for life-safety use.
Short pulses of one tone.
Used by siren and warble.
At 120, one pulse lands every 0.5 s.
Length of each pulse in the pulsing patterns.
Ready. Press play to sound the pattern.
The timeline is drawn from the same scheduled events the audio engine plays - one vertical bar per pulse, or a line tracing the rise and fall for siren and warble. It is a static drawing, not a live analyser.
An alarm has to beat whatever noise it competes with and pull attention without warning. Three properties do most of the work.
Pitch in the sensitive band
Human hearing is most sensitive between roughly 2 and 5 kHz, and the ear canal resonates near 3 kHz. A tone in that band needs far less energy to seem loud, which is why smoke alarms and reversing alarms cluster around 2–4 kHz. This generator caps the base tone at 4 kHz and defaults to a mid-range 800 Hz you can raise.
Repeated rhythm
A steady tone is easy to ignore; pulses are not. The brain treats a repeating on/off pattern as an event and keeps re-orienting toward it. Faster repetition reads as more urgent, and the classic alarm trade-off is between urgency (fast) and annoyance (too fast, for too long, at the wrong time).
Rise time and sweep
A slow rise and fall - the siren - is one of the most attention-grabbing shapes there is, which is why it signals emergency vehicles the world over. A sharp attack with a short decay, in contrast, gives the crisp “beep” of a device that wants a quick acknowledgement rather than sustained alarm.
Safety: this page exists to design and test alarm sounds, not to replace a certified alarm. Keep the level moderate, and never leave a loud repeating tone running near your ears or anyone else’s.
What is the difference between pulses-per-minute and BPM?
For the pulsed patterns (beep, double beep, pulse train) one cycle contains the pulse or pulses, so the rate is pulses per minute - 120 means two pulses per second. For siren and warble the rate is cycles per minute: one full rise-and-fall, or one complete back-and-forth, each cycle. The unit label next to the slider changes with the pattern so the number always means the same thing to you.
Why are the rate controls greyed out for continuous?
A continuous tone has no pulse to repeat and no rise and fall to cycle, so there is nothing for a rate to control. Only the base tone and the level apply. The page says so explicitly rather than leaving dead controls on screen.
How is the WAV export made?
The Save WAV button renders roughly ten seconds of the pattern in an OfflineAudioContext - the same pulse scheduling the live engine uses, just rendered faster than real time - then encodes it to a 16-bit PCM WAV at 44.1 kHz. The export is the exact signal, not a recording of your speakers.
Can I use these tones as a real alarm?
No. This is a browser test-signal generator. It stops if you close the tab or the browser suspends audio, it has no redundancy, no power-fail behaviour and no certification. Use it to design, demonstrate or test an alarm idea, then build the real thing with certified equipment.
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The full telephone keypad, A–D columns, dial tones, busy tones and SIT patterns.