About
About City Hum Daily
Small, free tools for the noise of everyday life: how loud it is, how long is too long, and how decibels add up.
What is here
- A sound level meter that reads your microphone, with A, C and Z weighting, Fast and Slow response, octave bands, a history graph and a CSV log.
- A noise exposure calculator for allowed time, daily dose and 8-hour TWA under the NIOSH and OSHA limits.
- A decibel calculator for adding, subtracting and averaging levels and for distance.
- A sound level chart of everyday sounds, with a hearing protector estimate.
- A tone generator with sweeps and WAV downloads.
How it works
Everything runs in your browser. The meter uses the Web Audio API to filter and measure the microphone signal a few times a second; the tone generator builds its sound the same way. Nothing you measure, type or play is uploaded, and the site has no accounts. Settings such as your calibration offset are kept in your browser's local storage.
Where the numbers come from
Exposure limits follow the published NIOSH criteria document (1998) and OSHA's noise standard, 29 CFR 1910.95. Safe-listening figures come from WHO and ITU, typical sound levels from WHO, the US National Institute on Deafness and Other Communication Disorders, and NIOSH. Each tool page lists its sources. The frequency and time weightings follow IEC 61672-1.
Limits
A browser and a phone or laptop microphone are not a calibrated sound level meter, so readings are estimates at best. The calculators apply formulas to the numbers you give them. Nothing here is medical, legal or safety advice: for workplace noise, ask a qualified occupational hygienist, and for hearing concerns, an audiologist or doctor.
The Recommended section on the home page and the footer also link to two other free tools, CleanTempMail and WebTraceCheck.