Okay then Steve do silent farts smell?
If you are interested I will give you my amateur science answer. Since energy cannot be created nor destroyed then whatever energy would have gone to producing that which our auditory senses would turn into a sensation of sound (though relatively little energy is involved compared to that released by a falling tree) would be changed into another form of energy such as the force of pounding an imperceptively larger crater.
Kate (of the Newton was a fig class)