CODEWITHSUNDEEP
androidaudiodecibel
Sandeep Manne
Sandeep Manne

Reputation: 6092

Calculate Decibel from amplitude - Android media recorder

How to calculate decibel from maxAmplitude, I wrote an android application to get maxAmplitude at regular interval, I need to show the o/p to the user in decibels.

Upvotes: 5

Views: 34905

Answers (2)

Nick H
Nick H

Reputation: 11535

Regular phone microphones aren't calibrated to measure absolute loudness, so it's not possible without also having a sound meter to initially calibrate the phone. As Oli mentions, you may be able to calculate a relative change in loudness, but I expect you want to replicate a real sound level meter.

Upvotes: 7

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272467

Decibels are a relative unit, they express the power of your signal relative to some reference power.

If you are working with amplitudes, then the formula is:

power_db = 20 * log10(amp / amp_ref);

(See http://en.wikipedia.org/wiki/Decibel#Field_quantities).

Note also that maximum amplitude is not usually a very good indicator of loudness (or even of power). More typically, you should measure the RMS power of your signal, and convert that to dB instead.

Upvotes: 12

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