My old guy Kima seems to have hearing loss also...and yet certain "sounds" can give him small seizures and if they are repetitive he will have a grand mal seizure. If he is sleeping the sounds do not seem to "register" with him. He sleeps on my pillow at night and I can feel his little jumps...
My 21 year + old cat started having seizures last April (2013). The first one that I witnessed was definitely triggered by the sound of the computer mouse and/or keys clicking. It was a Grand Mal seizure and I immediately took him to the vet. They found nothing wrong with him except slightly...