How ClearOne MicrophoneTechnology ImprovesSpeech Recognition Results

SpeechTEK 2007

Kurt OlsenDirector of Product MarketingClearOne

©2007 ClearOne Communications. Confidential and proprietary.

Topics

+ Why the microphone is so important in speech recognition

+ ClearOne audio devices: Chat 50 & Chat 150

+ ClearOne microphone technologies> Mic pickup patterns> Noise cancellation> Automatic level controls> Echo cancellation

©2007 ClearOne Communications. Confidential and proprietary.

Why the microphone is

so important in the

speech recognition equation

©2007 ClearOne Communications. Confidential and proprietary.

The challenge

“Hello”

“Hello”

Low volume level

Human hearing

©2007 ClearOne Communications. Confidential and proprietary.

The challenge

“Hello”

Low volume level

Human hearing

©2007 ClearOne Communications. Confidential and proprietary.

The challenge

“Hello”

“Hello”

Low volume level

Speech recognition

©2007 ClearOne Communications. Confidential and proprietary.

The solution:

ClearOne audio devices

Chat 50 & Chat 150

©2007 ClearOne Communications. Confidential and proprietary.

Chat 50

+ What is it? Multi-use personal speaker phonewith microphone, speaker, volume & mute

buttons

+ What does it connect to? PCs & Macs

Cell phones

Telephones

©2007 ClearOne Communications. Confidential and proprietary.

Chat 50

+ Features Full duplex audio (two-way)Rich audio with full bandwidth frequency response (20Hz – 20kHz)Echo cancellationNoise cancellationAutomatic level controls

©2007 ClearOne Communications. Confidential and proprietary.

Chat 150

+ What is it? Multi-use group speaker phonewith 3 microphones, larger speaker, volumecontrols

+ What does it connect to? PCs, enterprise telephones, videoconferencing systems

©2007 ClearOne Communications. Confidential and proprietary.

Chat 150

+ Features Full duplex audio (two-way)Rich audio with full bandwidth frequency response (20Hz – 20kHz)Echo cancellationNoise cancellationAutomatic level controlsAutomatic microphone gating technology

©2007 ClearOne Communications. Confidential and proprietary.

ClearOne microphone technologies: mic pickup patterns

+ Directional pickup pattern> Makes speech clearer by removing unwanted noises coming from sources

around the talker> Also attenuates (reduces) reflections in the room, eliminating the “bottom of

the barrel” effect> Goal: deliver an audio waveform that only contains speech – improves

speech recognition results

+ Chat 150 – has automatic microphone gating techniques

Cardioid microphone120-degree pickup pattern

©2007 ClearOne Communications. Confidential and proprietary.

ClearOne microphone technologies: noise cancellation

+ Removes ambient (constant) background noises> Air conditioner> Projector fan> PC fan> Fluorescent light hum

+ Detects constant state of noise, digitally removes from the outgoing audio stream

+ Increases the speech-to-noise ratio> How loud is my speech level compared to my noise ratio> The bigger the gap, the cleaner audio, and better speech recognition results

Noise floor level

Speech level

©2007 ClearOne Communications. Confidential and proprietary.

ClearOne microphone technologies: automatic level controls

+ Automatic level control> Adjusts loudspeaker volume up for soft talkers> Adjusts loudspeaker volume down for loud talkers

+ Automatic gain control> Adjusts microphone level up for soft talker> Adjusts microphone level up as distance increases between mic & talker> Adjusts microphone level down if too loud

+ Goal is to deliver intelligible audio that is loud enough to be understood by far-end listener or speech recognition engine

©2007 ClearOne Communications. Confidential and proprietary.

ClearOne microphone technologies: echo cancellation

+ Echo:> Outgoing audio is returned back to the listener> For open-air, two-way communications, echo cancellation is essential> Most devices just suppress outgoing or incoming audio

- Half-duplex – very difficult to carry out a meaningful conversation

+ ClearOne is a pioneer and industry leader in full-duplex performance with excellent echo cancellation technology

+ Speech recognition: audio bursts from PC (e-mail chimes, etc.) can result in interruption to speech audio and false recognition results

+ Our technology eliminates this problem – only audio coming into microphones from local room gets passed through, not audio from speakers

©2007 ClearOne Communications. Confidential and proprietary.

The bottom line

+ ClearOne’s advanced audio processing technologies deliver crystal-clear audio for audio conferencing applications, and also for speech recognition applications

+ Result: better translation of audio streams by speech recognition engines