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Sound Alerts: See the Sounds You Cannot Hear
A knock at the door, the doorbell, a baby crying in the next room, a dog barking at the gate. If you are Deaf or hard of hearing, these sounds pass you by. Sound Alerts keeps one ear open for you: it listens through your device's microphone for four everyday sounds and flashes a big, unmissable visual alert on your screen the moment it hears one, with a vibration on phones that support it.
Sound Alerts is a free web app that watches for four sounds: doorbell (including a ding-dong), knocking, a baby crying, and a dog barking. When it hears one, it shows a full-screen alert naming the sound, so you see it even with the phone across the room. You can teach it your own doorbell's exact chime in about ten seconds, and a built-in test mode plays sample sounds through the real detector so you can judge honestly what it catches and what it misses. Everything runs on your device: no audio is recorded, uploaded, or sent anywhere. It is a home convenience tool, not a safety device: never rely on it for smoke alarms, carbon monoxide alarms, or any emergency.
Open Sound Alerts
The four sounds
Each sound has a clear, published rule, and the app rejects near misses with a named hint instead of guessing:
- Doorbell: two clear chimes, the second the same pitch or lower (ding-dong). A single chime does not count: the app tells you "That was a single chime. Doorbells ring twice."
- Knocking: two or more short, sharp thumps close together. A single thump does not count.
- Baby crying: a sustained voiced sound whose pitch wobbles up and down in a regular rhythm. Steady talking is rejected: "That sounded like talking, not crying."
- Dog barking: two or more short, rough bursts with gaps between. One long rough sound does not count.
Because the rules are explicit, the app is testable: the built-in test mode feeds synthesized versions of each sound, plus the tricky wrong versions, through the real detector, so you can watch it catch the right ones and stay silent on the wrong ones.
Teach it your doorbell
Every home's doorbell sounds different. On the Teach screen, hold your phone near the doorbell, have someone ring it once, and the app records three seconds and learns the exact chime pattern: the pitches, the lengths, the gaps. Only the pattern is stored, as numbers, on your device: the audio itself is discarded. Afterwards, listening uses your recording instead of the generic ding-dong detector, and a Test button lets you check the match score any time.
How the listening works
Sound Alerts uses a small hand-written sound analyzer, not a neural network. It measures pitch, noisiness, and timing directly from the microphone signal, 16,000 samples a second, and checks each sound event against the four rules. The whole detector is a few kilobytes of plain code: no model download, no cloud, nothing to phone home to. That keeps it fast on old phones and fully explainable: the About page lists every rule, and the test suite proves each one with synthesized audio.
The microphone runs only while you are on the listening screen. Leave the screen, hide the tab, or close the page, and the mic turns fully off: your browser's mic indicator is the proof, and a page cannot hide it.
Alerts and history
When a sound is caught, a full-screen card names it in large type ("Doorbell", "Knocking", "Baby crying", "Dog barking", or "My doorbell"), with a vibration where your device supports it. Every alert is logged to an on-device history list with the time, so you can check what happened while you were in another room. The history, the taught doorbell, and your progress are stored only in your browser, and the Offline proof panel deletes them all with one button.
Practice and progress
The test mode is also a learning tool: eight rounds, each playing a sound through the real detector while you pick what it was from labeled options. Wrong picks always show the named hint, never just a score. Points, day streaks, levels, and badges (first sound caught, 50 sounds, taught my doorbell, perfect round, 7-day streak) keep it engaging, with confetti and chimes on wins that you can switch off. Practice stays the core: the game elements are seasoning.
Your audio never leaves your device
Microphone audio is measured and immediately discarded. Nothing is recorded, uploaded, or shared. The page security policy blocks connections to every outside server, and the built-in Offline proof panel shows a live log of every network request the page makes, lets you simulate a fully offline session, shows exactly what is stored on your device, and deletes it all with one button. The app works offline after your first visit.
Start listening
Training something else? Fingerspell teaches the ASL alphabet, Mandarin Tone Trainer coaches tones, and Face Switch teaches hands-free face control, all the same private, on-device way.
This is a home practice and convenience tool, not a teacher, therapist or safety device. Everything runs on your device: no audio is sent anywhere. Feedback is automatic and can be wrong. For real support, learn from the Deaf and hard-of-hearing communities linked on the Resources page. Sound Alerts is not a substitute for certified visual or vibrating smoke and carbon monoxide alarms. Never rely on it for any emergency.
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Frequently asked questions
What is Sound Alerts?
A free web app for Deaf and hard-of-hearing people that listens for four everyday sounds, doorbell, knocking, a baby crying, and a dog barking, and flashes a big full-screen visual alert naming the sound when it hears one. It is a home convenience tool, not a safety device.
Which sounds does it detect?
Four: doorbell (two clear chimes, ding-dong), knocking (two or more sharp thumps), a baby crying (a sustained wail with a regular pitch wobble), and a dog barking (short rough bursts). Each has a published rule, and near misses get a named hint instead of an alert.
Can it learn my own doorbell?
Yes. The Teach screen records three seconds while someone rings your doorbell, extracts the chime pattern (pitches, lengths, gaps), and stores only those numbers on your device. The audio is discarded. A Test button reports the match score any time.
Is this a safety device?
No, emphatically not. Sound Alerts is a home convenience tool. Never rely on it for smoke alarms, carbon monoxide alarms, or any emergency. It can miss sounds and misidentify them, and it only works while the app is open and listening. Use certified visual or vibrating alarms for safety.
Does it record or upload my audio?
No. Microphone audio is analyzed on your device and immediately discarded. Nothing is recorded, uploaded, or shared. The page security policy blocks connections to every outside server, and the Offline proof panel shows the live request log to prove it.
How does it tell the sounds apart?
A small hand-written analyzer measures pitch, noisiness, and timing from the microphone signal. A doorbell is two clear chimes; knocking is two or more sharp thumps; crying is a sustained voiced wobble; barking is rough bursts. Talking, background noise, single thumps, and single chimes are all explicitly rejected.
What happens when it hears something?
A full-screen card names the sound in large type, your phone vibrates where supported, and the alert is logged to an on-device history list with the time. Dismiss it with one tap.
When does the microphone run?
Only while you are on the listening screen. Leaving the screen, hiding the tab, or closing the page turns the mic fully off. Your browser's mic indicator shows whenever it runs, and a page cannot hide that indicator.
Does it work offline?
Yes, after your first visit. The app and the detector are saved on your device, so it works with no network at all. The Offline proof panel even lets you simulate a fully offline session.
What is the test mode?
Eight rounds where the app plays synthesized sounds through the real detector, mic bypassed, and you pick what was played from labeled options. Four rounds are tricky wrong versions (talking, noise, a single clap, a single chime) where the right answer is none of these. Wrong picks always show the named hint.
Can I delete my data?
Yes. Open Offline proof on the home page and press Delete all my data, or clear history and progress separately from the home and dashboard screens. Everything is stored only in your browser, on your device.
Who is it for?
Deaf and hard-of-hearing people who want a free, private convenience for everyday sounds at home: hearing the door, the baby, or the dog without wearing a hearing device every moment. For real support and community, the app links to the National Association of the Deaf and the Hearing Loss Association of America.