Sound instead of light?

Hi everyone,

LaBerge in his book "Exploring the World of Lucid Dreaming" and various posts here confirm that a light can elicit lucid dreaming, by acting as a clue for the sleeping subject. One sees the light, s/he remembers that this is a signal and s/he attains lucidity.
I guess this is the basis of the equipment developed by LaBerge and handicrafted masks.

If I remember well, LaBerge himself demonstrated that light is more efficient than other signals.

My question is: may sound be used as well? I mean, a sound signal instead of a light.

I tried some months ago with an alert system of my cell phone. I registered no success, but I am a bad lucid dreamer, so my experience is not reliable. Moreover that sound compelled me to wake up; since sleeping well is more important for health than having lucid dreaming, I stopped the experiment.

Any thoughts on sounds instead of light?

eXistenZ