EPUB 3.0 has support for Media Overlays, which allows you to synchronize text and audio.
My first Ebook reader had audio support, but my newest (bought 5+ years later) doesn't. It is not a feature that plays a part in selecting a device which is primarily for reading. Although there might be some novelty in having sound snippets in a particular book, in general it would probably be like 3D and Movies: it doesn't make the story any better and the effect doesn't compensate for the headache that it gives.
If I really wanted to read/listen to such a book I would probably such a book out on my PC.
If it makes sense completely depends on the added value. If it is just for novelty I would definitely say "no". Please also consider that apart from the people which do not have a device capable of rendering the audio, there are those who might happen to have such a device, but are not able to use it: the audio impaired part of the population (who are more dependent on book entertainment than others who can listen to radio/television).
If the audio is spoken text, another group that will not be able to fully appreciate the addition are those non-native speakers, capable of reading the book in the language it is written in, but not fluent enough to understand the spoken word.
A last comparison you might do for yourself: how many websites which support audio do you visit? (I am not talking about YouTube which is more just a wrapper around video/audio). That might be an indication of how useful adding audio to reading material is considered by you (and the general public if you observe the number of web sites with audio support).