How to get timestamps of "noise" in an audio file

[freakalot]

Hi,

I have a recording of some radio traffic where there is something spoken from time to time. I want to find an efficient way to get the timestamp of the start and end of any activity on this audio file. I was able to do it successfully by using a WaveOutEvent and SampleAggregator by init and play the WaveOutEvent. In my case it is not necessary to play the audio file so I would like to avoid the play call and just read the file as fast as possible.

This is the current state:

AudioFileReader audioFile = new AudioFileReader("path/to/my.wav");
SampleAggregator aggregator = new SampleAggregator(audioFile);
aggregator.NotificationCount = audioFile.WaveFormat.SampleRate / 100;
aggregator.MaximumCalculated += Aggregator_MaximumCalculated;

WaveOutEvent playbackDevice = new WaveOutEvent { DesiredLatency = 200 };
playbackDevice.Init(aggregator);
playbackDevice.Play();

private static void Aggregator_MaximumCalculated(object? sender, MaxSampleEventArgs e)
{
    bool isActive = false;
    
    if ((e.MaxSample > 0.001 || e.MinSample < -0.001) && !isActive)
    {
      isActive = true;
      playbackDevice.GetPosition();
    }
    if ((e.MaxSample < 0.001 || e.MinSample > -0.001) && isActive)
    {
      isActive = false;
    }
}

And on top of this, how can I detect noise on a selected channel of the wave file and not in general?

I hope anyone here has an idea or even implemented something similar and can help.

Cheers,
Frank