Just a meter.
Nothing more.
Real-time decibel readings, A-weighted dBA aligned with NIOSH guidance. The microphone stays off until you tap Start, and stops the moment you leave the app.
One-time purchase. No subscription. No account. No analytics. No backend.
What we promise
- The mic is off until you say so.
- Readings live on screen. Then they're gone.
- Nothing leaves your phone.
- There is no account.
- One purchase. Forever.
How it measures
Honest Decibel turns the iPhone microphone into a real-time sound level reading. It shows dBA, A-weighted decibels, because that is the scale built around human hearing and the one health agencies use for noise-safety guidance. Here is exactly what happens between Start and Stop.
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Microphone, on demand
The mic stays off until you tap Start. There is no background audio session, no startup popup, and the mic is released the moment you tap Stop or leave the app.
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Sample on device
The signal is read in real time and converted to a sound pressure level locally. No reading is uploaded; nothing is recorded or stored.
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A-weighting (dBA)
An A-weighting filter de-emphasises the very low and very high frequencies the ear is less sensitive to, so the number tracks perceived loudness. This aligns with NIOSH occupational noise guidance, which uses dBA and an 85 dBA / 8-hour exposure limit.
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Level, peak & haptics
The current level shows on one screen with a peak-hold marker for the loudest moment, and a haptic tick confirms each band crossing so you don't have to stare at the screen.
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Calibration offset (Pro)
Phone mics are tuned for voice and vary by device, so an optional calibration offset lets you nudge readings to match a reference meter. dBC and dBZ scales for low-frequency and venue work are part of the same one-time Pro purchase.
A phone is not a certified sound meter, for the science behind these limits see CDC / NIOSH, the WHO on hearing loss, and the OSHA occupational noise standard.
What it does, and doesn't
It does
- Show real-time dBA, A-weighted for hearing safety
- Hold a peak marker for the loudest moment
- Tick haptically as you cross noise bands
- Offer dBC / dBZ scales and a calibration offset (one-time Pro)
- Run fully offline, on iPhone
It doesn't
- Replace a calibrated Type 1/2 meter for legal or compliance use
- Record, store, or upload any audio
- Subscribe you, nag you, or run an expiring trial
- Create an account or phone home, no analytics, no SDKs
- Run on Android or the web (iOS only)
Questions people ask
How accurate is a phone sound level meter?
A phone is not a calibrated Type 1 or Type 2 sound meter. Its built-in microphone is tuned for voice, can compress very loud sounds, and varies by device, so treat readings as a good indication rather than a legally precise measurement. Honest Decibel applies A-weighting and offers a calibration offset to align it with a reference meter, but for compliance or legal work you still need certified hardware.
What is dBA and why does it matter?
dBA is the A-weighted decibel. The A-weighting filter reduces the weight of very low and very high frequencies the ear is less sensitive to, so a dBA number tracks perceived loudness, and it's the scale agencies like NIOSH use for hearing-safety guidance. Honest Decibel shows dBA by default for this reason.
What sound level is dangerous to hearing?
NIOSH recommends keeping exposure at or below 85 dBA over an 8-hour day, and the safe time roughly halves for every additional 3 dB. Sustained sound above about 85 dBA can damage hearing over time, and very loud events above ~120 dBA can harm hearing almost immediately.
Does Honest Decibel work offline?
Yes. The reading is calculated entirely on device, with no network required. There's no server call, no account, no analytics and no third-party SDKs, it works the same in airplane mode as online.
Is Honest Decibel a subscription?
No. It's a one-time purchase. The optional Pro tools (dBC and dBZ scales and a calibration offset) are also one-time, never an auto-renewing subscription or expiring trial, and future Pro tools are included for owners.
When is the microphone on, and does the app record me?
The microphone is on only while you're actively measuring, it turns on when you tap Start and off the moment you tap Stop or leave the app. Honest Decibel does not record or store audio; it computes a level in real time and nothing leaves your phone.
Make sense of a reading
Short, practical guides on what decibel numbers actually mean, from everyday sounds to concerts, headphones, and the nursery.
- Decibel Levels of Everyday Sounds: A Real-World dBA Chart (and When Each One Is Risky)
- How to Measure Neighbor Noise on Your iPhone (and What a Reading Can and Cannot Prove)
- How Loud Is a Concert in Decibels, and How Long Before It Damages Your Hearing?
- How Loud Is Too Loud for a Baby? Safe Decibel Levels for White Noise Machines
- Are My Headphones or AirPods Too Loud? How to Check Your Listening Volume in dB
Honest Decibel is one of the small, private iOS tools in the Keltek apps studio.