My mother in law works with deaf and hard of hearing children between 0-3 years. One thing they use for sensory play with infants is mylar balloons which are deflated.

I kept a balloon from when my little one was born and now, at three months, he is CRAZY about playing with it. He loves to hold it, taste it, and listen to the sounds. This is obviously a play object to supervise. I recommend trying it with your little one. They seem to love the feel and sound of it!