What`s Doing with Microphones?

ALMA
The Association of Loudspeaker
Manufacturers & Acoustics International
What’s Doing With Mic’s?
Sunday morning January 6, 2013
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Mic capsules are everywhere
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Speaker engineering is increasing becoming system engineering.
Wireless Bluetooth speakers include amplification, speakerphone
function, battery power management and so on. Most consumer
electronics that contain speakers also contain mic(s)… such as your
cellphone, laptop, webcam, camera, Bluetooth earphone and car kit.
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you might think the mic industry has become a mature commodity
business. Yet mic arrays, active mics (embedded preamps and codecs),
low-noise mics for active noise canceling, silicon MEMs mics are just a
few of the disruptive technologies shaking up the mic industry.
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This tutorial will review microphone technology such as the various
types including ECM and MEMs, the different types of active mics
including analog and digital outputs, active arrays, and embedded
signal processing. Recent trends in the industry, performance
breakthroughs, and key players and pricing will also be discussed.
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Topics for Mic Seminar
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ECMs mic capsules – what’s new
MEMs mics – what’s new
Active microphones – history and future
Signal Processing for active mics
What’s coming in 2013?
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ECMs – what’s new
• Super low noise
– ANC 70 dB+ S/N
• Matched mics
- Mic arrays
• Super small ECMs
- MEMs footprint
• Waterproof
– Sports earphones
• Shielded, filtering
caps
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Knowles dominated MEMs
mic market for many years
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Silicon MEMs
Micro Electro-Mechanical Systems
• MEMs mics are omni
pattern – directional
when used in arrays
• Today many MEMs Mic
competition and
choices on all fronts
• All MEMs Mics have
ASIC and many have
digital outputs
• Top mic port and
bottom mic port styles
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Lower cost MEMs
• Many Chinese ECM mic
vendors (Goertek, Horn,
AAC, etc.) now expanding
into Mems
• Most Chinese vendors buy
“kits” for assembly
- buy micro-machined
MEMs mic elements
- buy ASICs
then do the internal wiring and
chip packaging themselves
Pricing still above ECMs
because of ASIC cost
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High performance MEMs
• Akustica (Bosch)
and Knowles legacy
leaders
• ADI and ST now
low-noise leaders
• 65 dB+ s/n
• Good enough for
hearing aides and
anc
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ECM Active Mics
•2005 - National Semi introduced
preamp for ECM mic capsule
(analog) – ADI, Ti and others
follow… time to market reduced,
less surprises when the proto turns
on…
•Active mic = ECM + ASIC
•ASIC = application specific
integrated circuit
• active mic + embedded codec for
digital output
•Active mic + embedded smart
codec (miniDSP processing)
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ASIC mic preamp vendors
1.
2.
3.
4.
TI Texas Instruments -TLV1012, TLV1018
NS National Semi - LMV1012, LMV1032
Sanyo EC4K14MF
Fairchild (had the quietest) but they pulled
out of the codec business
5. Maxim-IC MAX4465-MAX4469
•ASIC - around 10 cents in big quantity…
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Some Signal Processing providers
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Forte Media
Noise Free Wireless
Acoustic Tech
Audience
CVC group at CSR
SRS (group of DTS)
Waves (Maxx Beam) Nuvoton
Iridium (voice recognition)
Typically offer ASIC or embed their algorithms (such as SRS and
CVC on CSR bluetooth ICs
• trend is for signal processing houses to move to offering their
algorithms to run on smart codecs
• Another trend is for signal processing licensers to be bought by
the big fish;
– Soft Max now part of Qualcomm
– Both Sonaptic and Dynamic Hearing now part of Wolfson Microelectronics
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Why active mics?
• ECM mics are “dry” = low level analog signal – 10 mv
average
• Low output of ECM mic is analog and can easily pick
up interference and needs external filtering
components
• Mic output signal path on circuit board is critical and
sometimes requires another layout of the board to
keep noise down – or even another layer on the
board for better grounding
• Active mics have the preamp gain right inside the mic
capsule case – preamp closeness to mic plus some
shielding of mic case minimizes noise pickup
• Output can be digital
• Much more likely to work first time
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ASICs – Plain and Fancy
• Analog mic preamp ASIC
• Mic preamp + codec A/D
• dual-mic ASIC analog signal processing
(Gtronix – National- Ti)
• Mic preamp + super codec with limited
signal processing and limited memory –
but low latency (Ti smartCodec or ADI
sigmaDSP)
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“Smart mics” ASIC processing
– use for what?
• Uplink and/or downlink signal
processing (talking/listening)
• Wind noise suppression
• Crowd babble (restaurant, open plan
office, audience noise)
• Intelligibility enhancement
• mic array beam forming (ADI 1772
has 4 mic inputs, 2 outputs
• active noise canceling
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“Active” mics and smart mic modules
• Specific markets…..
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Cellphones
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Bluetooth earphones and car kits
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speakerphones
Mic boom
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ODM sound pickup Zoom module
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for cameras and camcorders
smartphones
hands free car kits
bluetooth earphones
teleconferencing products
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National (Gtronix) dual mic module
•Original (Gtronix) System did
not work!
•Used the same miniscule bias
as ECM capsule alone
•Up to 20 dB noise reduction
•Programmable null
•Very low power consumption
•Appears like a 2-wire or 3-wire
mic to system
•Natural voice
•Wind noise alert and protection
• Actual implementation had high
noise floor
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Maxx Beam
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What to expect in 2013
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MEMs 67dB s/n
Lower MEMs pricing
Matched mic array modules
Dynamic tracking mic arrays of talkers
Enhanced water resistance
More Mic signal processing “on-board”
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