Questions
How accurate is a decibel meter on a phone or laptop?
Built-in microphones are not calibrated, so a reading can be off by 10 dB or more. If you need real numbers, set the offset against a calibrated sound level meter.
What is dBA?
dBA is the level with A-weighting, a filter that counts very low and very high frequencies less, close to how the ear hears. Most noise limits are given in dBA.
How loud is too loud?
Long exposure above 85 dB can damage hearing. At 100 dB the safe time drops to about 15 minutes a day.
How loud is a normal conversation?
About 60 dB at one meter. A whisper is around 30 dB, busy traffic about 80 dB and a rock concert 100 dB or more.