Estoy usando el siguiente código para crear dinámicamente un tono de frecuencia en la memoria y reproducir el tono de forma asincrónica:

public static void PlayTone(UInt16 frequency, int msDuration, UInt16 volume = 16383)
{
    using (var mStrm = new MemoryStream())
    {
        using (var writer = new BinaryWriter(mStrm))
        {
            const double tau = 2*Math.PI;
            const int formatChunkSize = 16;
            const int headerSize = 8;
            const short formatType = 1;
            const short tracks = 1;
            const int samplesPerSecond = 44100;
            const short bitsPerSample = 16;
            const short frameSize = (short) (tracks*((bitsPerSample + 7)/8));
            const int bytesPerSecond = samplesPerSecond*frameSize;
            const int waveSize = 4;
            var samples = (int) ((decimal) samplesPerSecond*msDuration/1000);
            int dataChunkSize = samples*frameSize;
            int fileSize = waveSize + headerSize + formatChunkSize + headerSize + dataChunkSize;

            writer.Write(0x46464952);
            writer.Write(fileSize);
            writer.Write(0x45564157);
            writer.Write(0x20746D66);
            writer.Write(formatChunkSize);
            writer.Write(formatType);
            writer.Write(tracks);
            writer.Write(samplesPerSecond);
            writer.Write(bytesPerSecond);
            writer.Write(frameSize);
            writer.Write(bitsPerSample);
            writer.Write(0x61746164);
            writer.Write(dataChunkSize);

            double theta = frequency*tau/samplesPerSecond;
            double amp = volume >> 2;
            for (int step = 0; step < samples; step++)
            {
                writer.Write((short) (amp*Math.Sin(theta*step)));
            }

            mStrm.Seek(0, SeekOrigin.Begin);
            using (var player = new System.Media.SoundPlayer(mStrm))
            {
                player.Play();
            }
        }
    }
}

El código funciona bien. El único problema es, ¿cómo sé cuándo dejó de sonar el tono? No parece haber un evento Completado en la clase SoundPlayer al que me pueda suscribir.