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Microsoft Windows Logo Program System and Device Requirements  —  85

Audio subsystem supports AEC reference inputs. Built-in or external audio devices that support full-duplex, stereo playback and record for speakers and microphone must support simultaneous capture of microphone and one or more AEC reference inputs.

At minimum, the audio device must support capture of microphone input in the left channel and a monaural output mix in the right channel, where the monaural output mix is the left and right channels of the main output merged into a single channel. This 1+1 channel interleaved format (similar to stereo) will be referred to as “mic+ref”, and can be easily achieved using existing stereo ADCs.

B3.1.4.12.1 Supports acoustic echo cancellation reference inputs.

See B3.1.4.12

B3.1.4.12.2 Does not rely on analog mixing.

See B3.1.4.8.4

B3.1.4.13 Headset microphone used for speech recognition meets performance requirements

The following requirements are for close-speaking headset microphones intended for use in speech-recognition applications. These requirements are compatible with most of the installed base of sound cards and audio-enabled system boards.

The requirements for a speech-recognition microphone are:

Close-speaking headset design positions microphone within 1.5 inches of the corner of the speaker’s mouth.

FSOV: 100 mV (0 dB FS).

Microphone connector meets requirements.

Operating bias voltage from 2.0–5.0 volts direct current (VDC) with a maximum current drain of 0.8 mA.

Capable of sustaining a maximum voltage of 10 VDC on tip or ring without damage.

Frequency response: ±3 dB from 100 Hz to 10kHz 0 dB at 1 kHz

Minimum sensitivity of –44 dB relative to 1 volt per pascal.

Maximum 2 percent THD+N 100 Hz to 10 kHz at 94 decibel sound pressure level (dBSPL).

Noise cancellation null sensitivity at 90 degrees and 270 degrees, ±10 degrees, with the following minimums: 20 dB at 100 Hz 20 dB at 400 Hz 20 dB at 1000 Hz 20 dB at 4000 Hz 10 dB at 10 kHz

Maximum wind noise sensitivity of –65 dB with 0 dB = 1 V (measured with wind speed of 1 meter per second at the 0 degree axis of microphone).

Maximum output impedance of 1 kilohm (using a 1-kHz full-scale test tone with 2.0 VDC bias).

B3.1.5 General Audio - FAQs

B3.1.5.1 Current related Audio FAQs

See http://www.microsoft.com/winlogo/hardware/.

© 1999-2002 Microsoft Corporation. All rights reserved.

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