The thing to keep in mind with AdWords display ads is that there is a serious file size limitation. For example, a 200 x 200 ad has a limitation of around 150 K. They don’t support streaming from a third party site, so the limit is what it is.
About audio in an ad - even it the audio does fit (and you are talking about not one but three audio files for browser compatibility) )people tend to really, really hate having audio in an ad unless they initiate the audio by clicking on a play button or something.
My advice for AdWords display ads: (1) Keep it simple and attention-getting. (2) Mind your file sizes. (3) Remember that the ad is meant to generate a click, not deliver a pitch.