No claimed acoustic accuracy tolerance
Decibel Reader has not been validated as a sound-pressure-level instrument against an acoustic standard. We do not claim an error bound such as ±2 dB, a Type 1 or Type 2 classification, or professional certification. Calculation tests can verify our arithmetic; they cannot establish the response of your microphone in a real sound field.
The live unit is Estimated dB. This tool does not implement A weighting, so the result is not dBA. It must not be substituted for an A-weighted exposure reading.
What can change a reading
- Microphone sensitivity and input gain. Different devices can deliver different digital amplitudes for the same sound.
- Frequency response. A device may respond differently to a low hum and a high-pitched sound even when a reference meter gives similar levels.
- Audio processing. Automatic gain, noise suppression, echo cancellation, or hardware processing can alter the signal. Requests to disable them are not guarantees.
- Placement. Distance, orientation, a covered microphone, reflections, wind, and handling noise affect what reaches the input.
- Signal limits. Electronic noise can dominate quieter sounds; loud sounds may overload the microphone or input before the browser sees them.
- Observation gaps. A suspended page or disconnected input leaves missing data. A short session may also miss an intermittent event.
What an offset can fix
A manual offset changes the display scale. Reference alignment calculates an offset to match a supplied reference reading under one condition. Neither changes the microphone's frequency response, noise floor, overload behavior, or browser processing.
We retain the Reference aligned label because the procedure depends on the reference you supply. A match at one condition is not validation at every level or for every source. The alignment guide explains how to perform and recheck it.
What other validation does not prove
NIOSH publishes tested specifications for its own iOS sound-level app, including requirements tied to a calibrated external microphone. This demonstrates why defined software, hardware, and test conditions matter. That validation does not apply to Decibel Reader or to your browser microphone.
Useful tasks and decisions that need more
Relative comparisons can be useful when you keep the device, orientation, gain, source conditions, and observation duration consistent. Repeat the comparison and describe it as an estimate on that setup.
For workplace exposure, a legal threshold, product certification, medical questions, or impulse noise, choose an appropriate calibrated instrument and measurement procedure. A browser report does not certify safety, establish compliance, or diagnose a hearing condition.
Reports keep the limits visible
Reports include the estimated or reference-aligned status and the applied offset. Keep that information attached when sharing a result. Add your own notes about the device, placement, reference settings, and conditions. Read the calculation method or make a repeatable room comparison.