Consumer audio products have always held a special fascination for me. Indeed, it was my childhood interest in audio gear that largely motivated my pursuit of an engineering career. But during most of my career, mainstream consumer audio technology has been pretty staid territory.
More recently, though, I've been delighted to see what I believe is the beginning of a revolution in consumer audio. The emergence of low-cost chips with heavy-duty digital signal processing capabilities is making it possible to bring new levels of quality, convenience and functionality to consumer audio products.
Some of the most interesting work is in sound reproduction: specifically, using sophisticated signal processing to overcome limitations in listening spaces and loudspeakers. At the recent Audio Engineering Society conference in Denmark, Bang and Olufsen demonstrated high-end speakers that compensate for imperfections in a room's acoustics. When first installed, they use sensors to gather information about acoustical properties. Processors in each speaker then run filter-design software to create filters that compensate for defects in the room's response. The resulting filters process audio signals before they are sent to the speakers' built-in amplifiers. In this way, the speakers eliminate certain unpleasant effects such as the "boominess" that can occur at low frequencies when a speaker is placed in a corner of a room.
Today this capability is available only in B&O's top-of-the-line, superexpensive speakers, but it is likely to trickle down into mainstream systems in the not-too-distant future.
Another promising application of signal processing in consumer audio is compensating for imperfections in the speaker driver itself. For decades, manufacturers have worked to improve loudspeakers through better electromechanical design, more advanced materials and tighter manufacturing tolerances. But for applications where costs must be tightly controlled and where weight and size are highly constrained, it may be more practical to use relatively poor transducers and correct their defects with signal processing.
Imagine coaxing acceptable sound out of the coin-size speakers in your laptop or symphonic sound from a $100 boom box. One day, inexpensive signal-processing chips will enable these and many other breakthroughs.
Jeff Bier is the general manager of Berkeley Design Technology Inc. (www.BDTI.com), a DSP technology analysis and software development company. Jennifer Eyre of BDTI contributed to this column.
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