Speech Technology Magazine


Clear As A Bell

Have you ever tried to hold a phone conversation at the office when the people in the adjoining office are doing the same thing? Noise is the enemy of voice communication at work, at home or on the road. Although noise is merely an annoyance during an ordinary phone conversation - you just speak a little louder, or repeat yourself when the din subsides - in some communications, it goes far beyond mere inconvenience.
By Greg Wright - Posted Jan 31, 1998
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Have you ever tried to hold a phone conversation at the office when the people in the adjoining office are doing the same thing? Noise is the enemy of voice communication at work, at home or on the road. Although noise is merely an annoyance during an ordinary phone conversation - you just speak a little louder, or repeat yourself when the din subsides - in some communications, it goes far beyond mere inconvenience. Aural pollution can cause crucial breakdowns in computer audio applications such as speech dictation, videoconferencing, Internet telephony and computer telephony integration (CTI). Muddy sound is particularly troublesome for Internet telephony and speech recognition. Specifically designed for computer audio applications, special headsets can dampen and even eliminate the clatter of the outside world. Free hands and privacy are side benefits. Computer headsets from Telex Communications, Andrea Electronics, Knowles Electronics and other manufacturers range in price from $30 to $240. The most advanced models, such as the Telex Nomad and Andrea ANC 100, feature noise-canceling microphones that, like those installed in airline cockpits and military vehicles, filter out background noise. Noise cancellation plays a vital role in speech recognition, a technology that is transforming the way humans interact with computers. The latest speech dictation programs (IBM VoiceType and ViaVoice, Dragon NaturallySpeaking, Kurzweil Voice for Windows) can convert speech into written text at up to 200 words a minute-a boon for those who can speak much faster than they can type. But the software still isn't smart enough to distinguish words from noises in the background (a creaking chair, a co-worker's cough). "It's these intermittent, extraneous noises that can throw off the recognizer and cause an error" said Taylor Norenberg, director of market development for Telex's Computer Audio Group. Acoustic clarity also enhances the performance of applications such as Internet telephony and videoconferencing. Long-distance callers on the Internet need all the help they can get to converse intelligibly in a medium struggling to overcome bandwidth limitations. Stripping out background noise allows users of Internet conferencing programs such as Microsoft NetMeeting and CoolTalk (a plug-in for Netscape Navigator) to concentrate on the conversation at hand. The same goes for desktop videoconferees, who gain an additional benefit: freedom from the screech of electronic feedback through satellite speakers. For example, the Nomad-NC computer headset supports environments such as Internet telephony, speech dictation and desktop conferencing - where a headset-mounted microphone is preferable and background noise poses a problem. Nomad's microphone relies on passive noise cancellation to screen out water-cooler conversations, the hum of computer fans, piped-in music and other extraneous sounds. A diaphragm inside the bi-directional microphone senses pressure differences between sounds emanating from the mouth and those originating from farther away. "Far-field" sounds are canceled out, leaving only unadulterated speech to travel down the headset cord into the PC. The headset, which retails for about $30, has been approved for use with IBM's Voice Type and ViaVoice, Microsoft's NetMeeting and Kurzweil's Voice for Windows.
Comparison of Noise Canceling Microphone Technologies
  Passive Noise Cancellation Active Noise Cancellation
Number of Microphones One Two
Microphone Element Type Bidirectional Omnidirectional
Frequency Response Pattern Same Same
Noise Cancellation Approach Acoustic Electronic
Noise Cancellation Performance Stability + + + + + +
  Single element has inherent balance over all frequencies, temperature and time. Dual elements and electronics susceptible to system imbalances over changing frequencies, temperatures and time.
Susceptibility to Electronic Noise None Moderate
Voice Recognition Performance + + + + + + +
Cost $ $$
Price/Performance + + + + + +
Andrea Electronics Corp. has also moved into the computer audio arena with a line of computer headsets adapted from communications devices used by the military. "We think we are on the verge of a marketplace that offers opportunity, particularly with the coming of the Internet, the mainstreaming of the PC," says John Andrea, co-president of the Long Island City, N.Y.-based firm. Andrea headsets such as the ANC 100 and ANC 500 employ active (electronic) rather than passive (acoustic) noise cancellation; a powered amplifier cancels the signal difference between two opposing omni microphones. Active-noise canceling microphones work just as well as the passive variety under most operating conditions, but cost more because of the extra electronics packed inside; the ANC 100 retails for $59.95. Those electronic components also make active mics more susceptible to electronic interference and fluctuating temperatures, which can degrade performance. Demand for computer headsets-and noise-canceling microphones in particular-is sure to rise as speech, telephony and PCs continue on their collision path. Yes, computer-aided communication will become relatively static-free as bandwidth swells (ATM is already replacing today's T1 and ISDN connections) and codes become more refined. But improved performance and lower prices inevitably bring technology into the mainstream. Within a few years, millions of people will be using Internet phones, desktop videoconferencing, voice dictation and other voice applications. And they'll still need a little help to make themselves heard in a noisy world. "The PC has become the preferred communications appliance," says Norenberg of Telex. "It's your phone, it's your e-mail, it's your fax, it's your videoconferencing link, it's your voice dictation station. Telex plans to supply the audio input/output devices that are required to enable these voice applications." Greg Wright is the director of product development and engineering at Telex. The company can be reached by phone at (612) 884-4051 or on the web at http://www.computeraudio.telex.com.
Comfort Headset
Comfort Telecommunications recently introduced the Comfort Aries Headset, which won Call Center Magazine's product of the year award. "The Comfort Aries combines the best technology of today with advancements that will service well in the future. The lightweight comfort, durability and affordability are all important factors in making the headset a superior product. The Comfort Aries also features advancements of superior sound quality, noise cancelling microphone, flexible spring boom, variable transmit volume control, dual mute switches, automatic gain control, "safety first" hearing protection, universal telephone interface and more," John Minto of Comfort said recently. Comfort also offers their repair service, which includes 24 hour repair turnaround, six month unconditional warranty, complete diagnostic testing on all equipment, original replacement parts and accessories, complete external polishing and sanitizing all at a low cost. For more information, call Comfort at (800) 399 3224. Andrea Headsets at SpeechTEK
Andrea Electronics announced at SpeechTEK that it will bring to market the first consumer PC headset which incorporates Active Noise Reduction earphone technology and Active Noise Cancellation microphone technology into a single unit, the QuietWare(tm) 1000/ANC. "We are proud to bring to market the first PC headset with ANR and ANC technology combined into a single unit," said Douglas J. Andrea, co-president of Andrea Electronics Corporation. "Our new advanced peripherals will become a key component in real-world desktop computing environments, especially with the growing acceptance and popularity of speech recognition, Internet telephony and all other voice-based PC applications." During SpeechTEK, Andrea also showcased for the first time its full line of patented, high-performance PC peripherals, designed to significantly enhance all voice-driven, PC and Internet applications in real-world, noisy environments. For more information contact Andrea at http://www.AndreaElectronics.com. Headsets from Shure
Shure offers a line of microphones designed specifically for computer applications. The microphones are of professional quality and feature tight frequency responses and true noise-cancelling polar patterns. The HW505, unidirectional electret microphone provides the perfect combination of comfort and quality at an affordable price. It features a unique light-weight, over-the-ears wire frame design with a high-quality stainless steel microphone boom. The HW505 is designed to provide optimum voice pick up and a higher recognition rate for computer speech input applications. The VR250B unidirectinal electret microphone with single earphone speaker features return audio and is the company's recommended choice for computer telephony and speech recognition programs with audio confirmation. The VR250B features a cushioned over-the-head design with twin earpads for wearer comfort and an adjustable high-quality stainless steel microphone boom. The HW501 unidirectional dynamic microphone is designed for software developers. It was the top choice of major software developers when they created the voice models for their speech recognition systems. The VR230D unidirection dynamic microphone with single earphone speaker is designed for users with a sound card that is non-powered and yet who require return audio. For more information,. Contact Shure at 222 Hartrey Ave., Evanston, Ill, 6002-3696; by phone at 800 25SHURE or at http://www.shure.com. Telex headsets at SpeechTEK
Telex Communications announced the first UHF wireless microphone for PC-based speech recognition applications at the SpeechTEK show recently. When used with a Telex Nomad-NC computer headset, the ProStar/PCWireless System provides users with an untethered, hands-free voice input device with the clarity and voice quality to support the latest speech dictation applications. For more information about Telex Computer Audio, visit the company's web site at http://www.computeraudio.telex.com.
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