WP7 SoundEffect volume decreases - windows-phone-7

Question

I can't figure this one out. If I click on a textbox, it sets up a timer to fire x number of times a minute. The timer seems to work fine, but the lower the cycles per minute, the lower the volume that the sound affect plays. I must not be understanding how the XNA framework works.
private System.Threading.Timer tmrMetronome_m;
private void tbTempo_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
TextBlock tb = (TextBlock)sender;
int iBeatsPerMinute = int.Parse(tb.Text);
int iMS = 1000 * 60 / iBeatsPerMinute;
if (this.tmrMetronome_m != null)
{
this.tmrMetronome_m.Change(new TimeSpan(0), new TimeSpan(0, 0, 0, 0, iMS));
}
else
{
this.tmrMetronome_m = new System.Threading.Timer(MetronomeTick, null, new TimeSpan(0), new TimeSpan(0, 0, 0, 0, iMS));
}
}
private void MetronomeTick(object state)
{
using (System.IO.Stream strWAV = TitleContainer.OpenStream("wav/Beat.wav"))
{
SoundEffect effect = SoundEffect.FromStream(strWAV);
FrameworkDispatcher.Update();
effect.Play();
}
}

Answer 1

Are you sure there isn't some other issue at play here? Could the beats possibly be overlapping to create the impression of being louder when they occur more often?
I recreated pretty much your exact code above in a quick XNA project, and did not experience the loudness issue. I was not -- obviously -- using the same audio sample though.

Answer 2

You may want to try moving that Stream reading out to the initialization somewhere. Store the sound effect contents into a SoundEffect variable during your app loading time and then call Play() on this variable during the MetronomeTick.
Depending on your wants, an alternative is to only store a SoundEffectInstance variable, and then during load time, load it up like so:
using (System.IO.Stream strWAV = TitleContainer.OpenStream("wav/Beat.wav"))
{
SoundEffect effect = SoundEffect.FromStream(strWAV);
soundInstance = effect.CreateInstance();
}
To play it, just call Play() on the SoundEffectInstance object.
Of course, because you're only keeping one instance, two of these sounds will never overlap (not sure of what you want). Either way it's worth trying if this problem still persists.