Remember what a big hit Guitar Hero was when it came out? All of us air guitar amateurs were able to justify and perfect our skills at playing in a rock band -- all in the comfort of our family rooms. If you are a MEMS nerd like me, you may recall MEMS played a significant role in the success of Guitar Hero. (Without the tilt motion sensing provided by the MEMS accelerometer inside, we might as well be playing "Kumbaya" instead of "Walk this Way.")
After hearing the beautiful sound achieved with the high-performance MEMS microphone that Rob O'Reilly of Analog Devices demonstrated at Sensors Expo 2012, I have the same kind of anticipation for what kind of rock stars this device might unleash. What makes this MEMS mic so different is that the sound is so clear and perfect that it can make anyone sound like a rock star, sans the million-dollar recording studio. What's more, my sources at Analog Devices tell me this "smart" device is also a lower-cost one.
What makes it smart? According to the folks at Analog Devices, the MEMS microphone's technology provides a higher signal-to-noise ratio for better near- and far-field performance, as well as flatter frequency response and noise rejection. This ultimately produces higher-quality sound. Throw beam forming, directionality, and proximity response into the mix, and you have a microphone for a wide range of applications.
With all deference to the Walt Disney Company, I asked O'Reilly how ADI makes the magic. "With our MEMS microphone, we integrate more of the signal chain than any other MEMS mic by integrating a MEMS transducer with a proprietary audio ASIC that leverages our decades of audio signal-processing experience." (In the video below, you can learn more about the MEMS mic from my interview with Jerad Lewis, microphone applications engineer at Analog Devices.)
There are several manufacturers in the MEMS microphone space, including Akustica (part of the Bosch Group), Knowles, STMicroelectronics (whose technology was jointly developed in a partnership with OMRON), and a few smaller players. I don't want to start a contest of whose MEMS mic is better. I happened to hear O'Reilly's demo, and I was astounded by the sound quality. I am all ears if anyone else wants to demonstrate the amazing qualities of a competing microphone. Or you can hire me to record a little something for the Grammys. That would be good, too!
Why is a smart mic important? For starters, in the consumer market, a smart MEMS mic is optimal for high-end audio capturing applications/products like conference phones, studio mics, DSLR cameras, smartphones, tablets, and headsets. The smartness of a MEMS mic will differentiate these products from their low-end (and low-intelligence) counterparts. But let's not stop with the consumer applications. Smart MEMS mics can find themselves in other markets, including industrial, health/medical, military/public safety, security systems, and you can take it from there. (I actually encourage you to let your imagination run with it -- going along with my mantra and vision of "MEMS everywhere.")
The most significant aspect of this device is processing the data at the sensor. This is becoming viable with integration of the ASIC and the MEMS sensor. Until recently, wireless mics used analog signals to the receiver because the delay introduced by signal processing would be noticeable. This is similar to the situation with smart cameras. With the amount of processing available in embedded SOCs, much of the signal work can be done without transmitting the data. This also allows, as in the case for the mic, real time correction of the signal, if required. The significance of MEMS is that it can more easily be integrated with circuitry than other types of sensors. This is the way to go.
naperlou thanks for your post on the blog - I totally agree that "this is the way to go" and I look forward to seeing how more and more processing will be done at the sensor. I hope that more folks (like you) will read this blog and get inspired with how to integrate and design in these smart MEMS sensors into more and more applications. Thanks again! Karen
The thing that makes music what it is comes from the distortions provided by the instrument. Otherwise we get somethng like the electronic music of the 1960's era. So it is not clear just exactly is meant by making things sound better through processing. Perhaps itwill be possible to compensate for the distortion from the microphone element, which could indeed offer an improvement, and it should certainly be easy to shape the frequency response to just about any curve desired. But eliminating noise without the ability to know what the noise is at any particular instant will probably have some unintended results.
The biggest advantage will be in reduced cost and smaller size, followed by a reduction in the installed cost.
Chuck, you are correct! What is interesting about these sensors is that they perform basic DSP functions right on the chip. While many microcontrollers have built in DSP hardware these days, it is still more efficient to have that function performed at the sensor.
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