Dolby. That's all I have to say and you think of "audio" and "surround sound". What's that company up to recently? Dolby Volume: a technology that equalizes the volume across all audio coming out of your TV. The system aims to deliver consistent volume for TV channels, programs, and commercials.
Dolby Volume models how "humans perceive audio" to eliminate variable loudness in the audio stream, automatically. Dolby claims user intervention completely is unnecessary (aside from the initial setup). The system handles up to a 30dB in reduction or amplification. Ars Technica mentions that Dolby did not address what Dolby Volume does when explosions or other sudden noises are meant to happen.
Dolby Volume is an innovation on technology already present in some television sets, DVD players, TiVos, and even digital music players. Dolby claims, and reporters at a demonstration have confirmed, that the idea is to adjust volume quickly without any delay or drop in audio quality. Although pricing has not been released by Dolby, the company hopes that television makers will be able to incorporated the technology into their products by the end of 2007.
News source: Ars Technica