Volume Control

Sound is propagating in the form of waves. When talking about sound waves, the volume is the perception of loudness from the intensity of a sound wave. The higher the intensity of a sound, the louder it is perceived in our ears, and the higher volume it has.

If you represent the sound with an int16_t then at maximum volume the values as oscillating between +-32767. To decrease the volume you can just decrease this amplitude by multiplying it with a value < 1.0. If you multiply with 0.0 you have no sound - if you multiply by 0.5 you have halve the volume.

You can use the ConverterScaler class to set the volume. Here is an example sketch which just sends the output :

#include "AudioTools.h"

using namespace audio_tools;  

uint16_t sample_rate=44100;
uint8_t channels = 2;                                      // The stream will have 2 channels 
SineWaveGenerator<int16_t> sineWave(32000);                // subclass of SoundGenerator with max amplitude of 32000
GeneratedSoundStream<int16_t> sound(sineWave);             // Stream generated from sine wave
CsvStream<sound_t> printer(Serial, channels);              // ASCII stream 
StreamCopy copier(printer, sound);                         // copies sound into printer
ConverterScaler<int16_t> volume(1.0, 0, 32767);            // volume control

// Arduino Setup
void setup(void) {  
  // Open Serial 
  Serial.begin(115200);

  // Setup sine wave
  sineWave.begin(channels, sample_rate, N_B4);
}


// Arduino loop - repeated processing 
void loop() {
  copier.copy(volume);
}

You can adjust the volume now dynamically by calling volume.setFactor(0.0) to mute the output or volume.setFactor(0.5) to halve the volume...