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akofman / cordova-plugin-dbmeter

:microphone::mega: Cordova plugin to get decibels from the microphone
Apache License 2.0
34 stars 29 forks source link

DBMeter counting limited to 90 #13

Open caiocssta opened 5 years ago

caiocssta commented 5 years ago

Hey!

I noticed that the counter is limited to 90 for me, and when the dB is higher than that, it just freezes at 90. Is that a bug, or some proposital thing?

Thanks anyway, love that plugin!

nexorianus commented 5 years ago

getting max 91 on iOS and Android

patrik1470 commented 5 years ago

Anyone found out?

albernaz commented 5 years ago

I've found this: Most microphones are aligned to human voice (300-3400Hz, 40-60dB). It is enough for voice calls. But it occurs an issue of 16 bits microphone limitation.

Look at sound pressure in calibrate menu. It'll stop at 32767 (32767=2^15-1). Therefore, 16 bits microphones cannot measure above 96 dB (more link).

And more, the max becomes 80-90dB due to calibration. Galaxy S3-S5(81-84db), HTC Desire HD(85db), Galaxy Note(81/91db).

※ Examples of sound pressure 20dB : Rustling leaves, Ticking watch 30dB : Quiet whisper at 3 ft, Library 40dB : Quiet residential area, Park 50dB : Quiet office, Quiet street 60dB : Normal conversation at 3 ft 70dB : Busy traffic, phone ringtone 80dB : Busy street, alarm clock 90dB : Factory machinery at 3 ft 100dB : Subway train, Heavy snoring(2ft) 110dB : Rock music, Screaming child 120dB : Threshold of pain, Thunderclap 130dB : Jet engine at 100 ft 180dB : Space shuttle lift-off