How test answers the audio boom

Bruce Hofer Chairman and Co-founder Audio Precision Beaverton, OR Bruce Hofer co-founded Audio Precision in 1984 with a group of audio engineers from the labs of Tektronix. In addition to serving as board chair, Hofer remains technically active as the company's principal analog design engineer. He has received 12 patents and has written many articles and papers, and in 1995 he received the Fellowship Award from the International Audio Engineering Society (AES). Hofer earned his BSEE degree from Oregon State University in 1970. Contributing editor Larry Maloney spoke with Hofer about trends in the audio test market in a recent telephone interview. Bruce Hofer comments on ease-of-use challenges, audio products, new application support programs, and other issues in the continuation of this interview.

Q: This year, your company surveyed engineers on the “future of audio.” What did you find?

A: Probably the most significant finding was confirmation of an emerging multichannel market that we’ve been sensing for years. The survey showed that the percentage of engineers needing audio analyzers with only two channels is expected to drop from 62% today to about 37% five years from now. For the same period, the percentage of those who require six channels or more is expected to rise from 16% to 33%.

Q: What are the biggest changes in audio, and how are they affecting test?

A: Over the last decade, we’ve seen a progressive increase in digital content in audio products, and I don’t mean just analog-to-digital converters. Signal processing has moved almost entirely from the realm of analog design to digital. Among the benefits are greater versatility and accuracy, and the implementation of audio features that were impractical with analog, such as very sharp bends, limiting filters, and artificial reverberation.

But there’s a dark side, too, in that the audio contains digital artifacts that we call out-of-band noise. This energy is well above the audio band, and while it will never get to your loudspeaker, it can have some very interesting effects on the next device that you hook it to, as well as to your test instruments. We need to use very sharp bandwidth-limiting filters to exclude the effects of this out-of-band noise.

Q: How about the evolution in audio products?

A: Audio devices deliver an increasing level of functionality, often in very compact packages. We’re witnessing a fusion of what were once distinctive or classic products, such as the cell phone. Now, the cell phone is being merged with a digital camera, and how long will it be before we see the cell phone merged with an MP3 player? Audio products are growing more sophisticated, more multipurpose, and more portable. All this influences the features that engineers will want to test. At the same time, we see high-end, multichannel audio systems for home theater and for automotive. It’s not uncommon for cars to have 10-, 12-, or even 14-channel systems.

Q: How are these developments affecting your instrument offerings?

A: To address this growing multichannel market—from autos to Dolby 7.1 to traditional mixing consoles—we introduced our APx585. This analyzer, which comes with easy-to-use PC-based software, features eight analog audio inputs and eight analog outputs. It also supports eight channels of digitized audio. This ability to test more than two channels at any one time has obvious throughput benefits for test engineers and their companies.

Q: Do you see a greater need to serve engineers who don’t have a strong audio background?

A: A very strong “yes.” Many technical schools are focusing more and more on digital technology, and less on analog. Many R&D facilities also are designing consumer products that need to be mass-produced, typically offshore, by contract manufacturers. In those locales—China, Southeast Asia, and so forth—you find a wide variety of backgrounds in production test engineers. Many of them have not been exposed to some of the specialized parameters that we measure in audio, such as distortion or signal-to-noise ratio. So, a growing part of our job is providing the training and support that these engineers need.