LAS VEGAS -- The connected car brings many advantages to the driver, but will also mean degraded music quality as people increasingly use streaming audio-services. At CES 2014, Harman announced Signal Doctor, a digital signal processor technology that attempts to restore fidelity to compressed audio.
Typical digital audio tracks bought from Amazon and iTunes are compressed to 128 or 256Kbps, and streaming audio from the likes of Pandora and Spotify is often down to 64 or 96Kbps. That much compression means a lot of lost information from a music track, which diminishes the sound quality.
Signal Doctor analyzes the audio signal in real time, and attempts to predict and restore the part of the signal that was lost.
The technology restores peak levels and high frequencies, all of which compression technology tends to discard. It also isolates vocals and enhances them.
During a demonstration here at CES, Harman played a variety of low-bit-rate tracks, including AC/DC's "Back in Black" and Sarah McLachlan's "Building a Mystery," using a graphic audio analyzer to show where compression had cut off the frequencies. When the Signal Doctor bypass was switched on, areas that appeared flat in the original graphic analysis were filled in.
The listening experience was greatly improved. The unprocessed compressed tracks often sounded muffled and lifeless. Signal Doctor added richer tones to the music. When played in a, the soundstage for the music widened considerably.
Signal Doctor is a software algorithm that Harman can load into digital signal processor hardware. It dynamically scales itself depending on how much music is compressed, applying its full capability to the most compressed music, and letting uncompressed audio, such as from a CD, play through without interference.
Currently, the Signal Doctor technology is available in the JBL Authentics line of powered speakers. Harman, as a major automotive supplier, will also make the technology available to automakers.