TI embraces digital mics

PORTLAND, Ore. — Digital microphone pioneer Akustica Inc. said it has gained a design win in Texas Instruments' latest stereo audio codec chips.

Dallas-based TI claims to be the first to add a digital microphone input to its codecs used in cellphones and other consumer audio devices. TI's TLV320 includes a I2S (Integrated Interchip Sound) pin enabling Akustica's digital microphone to bypass the usual analog-to-digital converter.

Akustica introduced what it claims is the world's first digital microphone in 2006. Texas Instruments "recognizes that digital microphones are becoming more commonplace," said Kaigham (Ken) Gabriel, co-founder of Pittsburgh-based Akustica. "We just sold our two-millionth digital microphone. It took us 15 months to sell our first million, but only three months to sell the second million."

Akustica's tiny digital microphone can now directly connect to TI's codecs.

Gabriel claimed that digital microphones are emerging because they deliver a discernible difference in audio in consumer devices by using the entire 20 Hz-to-20 KHz audio spectrum. Analog mics use only 5 KHz. For services like voice-over-Internet Protocol, the extra bandwidth may be the key to broader user acceptance, Gabriel argued.

"When you use a digital microphone, or better an array of them, it just sounds remarkably better compared to what we are used to hearing over the telephone," said Gabriel.

Using arrays of digital microphones would enable sophisticated noise cancelling as well as beam forming that could track a users' voice as their head moves relative to the microphone.

Along with Akustica, other suppliers include Knowles Acoustics (Itasca, Ill.), Sonion MEMS A/S (Roskilde, Denmark) and MEMS Technology Bhd of Singapore. Market researcher Yole Development recently counted 20 companies currently developing digital microphones. Any of these microphones could make use of the new digital input to TI's TLV320.