i need to generate pure tone开发者_如何学Gos with different levels of decibels (dB) in java. is there any example of how to do this?

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Tones with midi Synth

You can generate tones with the synth :

import javax.sound.midi.*;

public class MidiSynthesizerSample {
  public static void main(String[] args) {
      int[] notes = new int[]{60, 62, 64, 65, 67, 69, 71, 72, 72, 71, 69, 67, 65, 64, 62, 60};
      try {
          Synthesizer synthesizer = MidiSystem.getSynthesizer();
          synthesizer.open();
          MidiChannel channel = synthesizer.getChannels()[0];

          for (int note : notes) {
              channel.noteOn(note, 50);
              try {
                  Thread.sleep(200);
              } catch (InterruptedException e) {
                  break;
              } finally {
                  channel.noteOff(note);
              }
          }
      } catch (MidiUnavailableException e) {
          e.printStackTrace();
      }
  }
}

Where you can set up the volume of the channels, with

getSetChannelVolumeMessage(int, int)

http://www.springworldgames.com/rmleditor/javadoc/com/springworldgames/music/MidiUtils.html#getSetChannelVolumeMessage(int, int)

I don't know how to convert it to decibels, maybe it depends on your sound-card's volume level.

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This http://jsresources.org/examples/OscillatorPlayer.html shows how to create pure sinusoidal (or pretty much any other) waveforms and play them. As for decibels, their relation to amplitude is db ~ 20 * log10 (amplitude), i.e. amplitude ~ 10 ^ (dB/20), so just calculate from that.