android: Detect sound level

Question

Using MediaRecorder I capture sound from device\'s microphone. From the sound I get I need only to analyze the sound volume (sound loudness), without saving the

Answer 1

If you want to analyse a sample of sound taken directly from the microphone without saving the data in a file, you need to make use of the AudioRecord Object as follows:

int sampleRate = 8000;
try {
    bufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_IN_MONO,
        AudioFormat.ENCODING_PCM_16BIT);
    audio = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate,
            AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT, bufferSize);
} catch (Exception e) {
    android.util.Log.e("TrackingFlow", "Exception", e);
}

Then you have to start recording when ready:

audio.startRecording();

Now it's time to start reading samples as follows:

short[] buffer = new short[bufferSize];

    int bufferReadResult = 1;

    if (audio != null) {

        // Sense the voice...
        bufferReadResult = audio.read(buffer, 0, bufferSize);
        double sumLevel = 0;
        for (int i = 0; i < bufferReadResult; i++) {
            sumLevel += buffer[i];
        }
        lastLevel = Math.abs((sumLevel / bufferReadResult));

The last code combines all the different samples amplitudes and assigns the average to the lastLeveL variable, for more details you can go to this post.

Regards!