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New Dolby Sound for Mobile Devices

Dolby Digital Plus Aims To Create Better Personal Audio


New Dolby Sound for Mobile Devices
Dolby Labs

As more people turn to mobile players like phones and tablets for their movies, TV and music, the limitations of playback quality on those devices become ever more clear. 

On the video side, the improvements are there, and with good bandwidth, and a nice HD screen, you really can see a pretty good picture.  But in most cases, the sound on these devices has lagged far behind.  It isn't just a question of headphone quality, or even the output quality of the device itself, which if you're listening through headphones is usually nothing more than a few cents worth of 1/8" analog jack anyway -- hardly hi-fi.

The real problem is that the original audio you're listening to -- particularly for movies and TV shows -- was never recorded or mixed to be a headphone experience.  Think of the last blockbuster movie you saw in the theater or listened to through your home theater.  Think of all the big dynamics, the loud sounds of things blowing up, the soft surround sounds that put you in the scene. 

To get the Dolby Digital sound experience in a movie theater, there are often a dozen or more speakers at work.  To get it in your home theater, there are six at least, and sometimes eight or more.  When you try to listen to the same material through headphones -- two speakers, left and right -- there's a tremendous disconnect, both technologically and perceptually. 

Dolby Labs has come up with a new audio treatment called "Dolby Digital Plus" which has been designed specifically to take the multi-channel movie experience and re-cast it for headphone (or sound dock, etc.) audio playback and other applications of what Dolby calls "evolving media."

The Listener's Problem

From an audio perspective, movies -- so far -- are not recorded or mixed to create a personalized listening experience.  Nor are they designed for the tiny and tinny speakers featured on virtually every tablet (make that speaker singular for the iPad), or for the tiny, barely powered amplifiers built into these devices.

This is why loud passages in movies badly distort when you watch on a mobile device.  It's also why dialogue often gets lost in a personal listening environment; in the intended context, that all-important audio gets assigned it's own dedicated speaker(s).  It's also why many people end up watching their movies with one finger on the volume control, so you can turn down the crazy loud parts and then bring up the soft parts enough so that you can follow the dialogue and the story.

Dolby's Solution

What Dolby Digital Plus does is run the movie's audio through a series of algorithms that tailor the sound to a small-speaker environment (think headphones or built-in tablet speakers), taming the broad dynamics and wide frequency range of a true Dolby Digital movie and making it more palatable for miniaturized speaker playback.

Specifically, Dolby Digital Plus performs some fancy tricks with dynamic compression, intelligent equalization and spatial cues, such as:

A Volume Maximizer function that brings up soft signals but restricts the loudest audio peaks so they don't overload and distort (or annoy you);

A Volume Leveler that lets you set a "master" volume to your preference and then adjusts your content to play back at that relative volume, so you're not constantly riding the volume control;  

A Regulator feature that compensates for the expected distortions when tiny speakers receive audio signals that are louder than they were designed to play;

A Dialogue Enhancer that better separates dialogue from background sound to make dialogue more intelligible;

Enhanced surround simulations that try to expand the 2-channel headphone experience to something that sounds like a larger space;

And a few other secret ingredients that Dolby intends to license to as many hardware partners as it can. Dolby Digital Plus technology has already found its way into the Amazon Kindle Fire HD.  Expect many others to follow by the time the holidays roll around.

Dolby isn't the first to understand that headphones are the new speakers.  Beats technology, for example, was once relegated strictly to a line of upscale headphones.  Now, with the company being purchased by phone maker HTC, Beats "sound" will show up in millions of mobile devices. 

Better sound is a good selling point for devices that people listen to music and movies through.  Dolby figures that between its name recognition and its audio innovations that it's got a good chance to be the marquee name on your tablet as well as your home theater.

There are demos of Dolby Digital Plus available on the Dolby web site.  Check them out and hear for yourself the next big thing in personal movie playback.

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