decibel

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. 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

The AVAudioRecorder in the iPhone SDK can be used to get the peak and average power for a channel, in decibels. The range is between 0db to 160db. What is the calculation used to convert this into a scale between 0 - 10 or something similar that can be used for an audio level meter? The range is from -160 dB to 0 dB. You probably want to display it in a meter that goes from -90 dB to 0 dB. Displaying it as decibels is actually more useful than as a linear audio level, because the decibels are a logarithmic scale, which means that it more closely approximates how loud we perceive a sound. That

I am new to Android and looking to write an app for measuring decibel sound level . The idea is that when a sound reaches a certain level the user gets a alert. That's it. Can anyone help me out with this. Can I do this using HTML5/Javascript ? any help will be appreciated. Soham Taken from Android Media Player Decibel Reading For native android/java based decibel calculation for a MediaRecorder: mRecorder = new MediaRecorder(); mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mRecorder.setAudioEncoder(MediaRecorder

The Android MediaRecorder has a function .getMaxAmplitude(); which, as the API tells me, "Returns the maximum absolute amplitude that was sampled since the last call to this method." but I can't find what amplitude this is? Is it in pascal or watts? I have found on several pages on the web that you can calculate a value closely corelated to decibels using (as suggested here ). double db = (20 * Math.log10(amplitude / REFERENCE)); which would let me assume that the returned value is in some linear scale (probably something like milipascal...) REFERENCE=0.1 (I am aware that this should be