Cirrus Logic DSP Uses Dolby Volume for Steady Sound Levels

By incorporating Dolby Volume controls on its new CS48DV2 digital sound processor (DSP), Cirrus Logic adds technology to keep sound levels steady to its product offerings. The Dolby Volume control lets users establish a sound level for listening that remains steady even when commercials come on (a favorite time for broadcasters to boost volume levels), when changing channels, or when switching from one signal source to another (from set-top box to DVD player, DVR, media PC and so forth).

DSPs may not look like much, but they carry plenty of processing power.

The Dolby Volume technology rides on a sound processing engine that exploits Dolby Labs’ 20-plus years of research into how the human ear works and processes sound. Whereas old fashioned gain controls or gain limiters take a more brute force approach to managing signal strength, the Dolby technology takes a more organic approach designed around human hearing and sound perception. In fact, because of loss of detail at low sound levels in the human hearing apparatus, various subtleties are often lost when sound goes quiet. Dolby uses two volume control technologies in the Dolby Volume implementation. Its Volume Modeler technology to perform continuous audio analysis and modification based on current sound content and playback levels, to render it as much like reference playback levels as possible. This is what lets the circuitry react to changes in volume levels without over-reducing spikes, or under-representing valleys. The Volume Leveler, on the other hand constantly measures perceptual loudness, and applies multi-band gain modifications using a perceptual processing engine. This is what permits audio to manifest approximately equal sound levels from all kinds of sources. The CS48DV2 DSP is available in a 48-pin QFP package, and is priced at $4.78 per unit in quantities of 10,000. This adds very little to the cost of a television set, so it’s not unreasonable to expect many new 2008 models, especially HDTVs, to begin incorporating and touting Dolby Volume control. To us, it certainly sounds like an excellent chip, especially for those who like to watch late-night TV in environments where volume spikes are likely to disturb sleeping dogs, neighbors, or children. For more information, see this Cirrus Logic press release.