UmeVoice, Inc.Vikas Rangarajan, Sr. Software EngineerAdithya M.R. Padala, President & CEO.

Noise cancellation technology for delivering clear audio

Introduction

• Speech recognition in mission-critical application environments: Wall Street trading floor: BUY 10000 IBM at 93-1/4

• Problem of successful speech recognition in highly noisy environments

• Searched the world for best noise-cancelling solution

• Serendipitously led us to the development of our own noise-cancelling technology to effectively provide clear audio while eliminating 100+dB of background noise

• Use of this technology to develop products for clear communication and accurate speech recognition.

• theBoom

Why Audio Clarity is Crucial

• High signal-to-noise ratio: amplitude of desired signal (speech) is much higher than the noise

• Flat frequency response: the speech signal is passed through with minimal change to the frequency spectrum

• Face to face human communication is more tolerant to noise mixed with speech

• For long-distance human communication, audio clarity is more important

• Imperative for speech recognition

Importance of clear audio for VoIP

• Increasing mobile usage of VoIP applications• Noisy environments are typical (airports, conferences, cafes)• A clear speech signal enables applications to use Variable Bit-

Rate (VBR) and Average Bit-Rate (ABR) more effectively• Elimination of background noise improves VAD (Voice Activity

Detection)• Improved bandwidth utilization by effective silence detection

using techniques like Discontinuous Transmission (DTX)

The passive approach and its benefits

• Prevention of noise from entering an audio signal without using a feedback mechanism

• The mechanism is based on acoustic principles of sound waves

• Real-time information about the noise or the desired sound signal is not used by the mechanism performing the noise-cancellation. This eliminates the need both for a processor and therefore a power supply.

Electronic noise cancellation

• Digital Filters: Signal enhancement using digital signal processing

• Active Noise Reduction: Noise is reduced by generating a cancelling anti-noise signal which is equal to, but 180 degrees out of phase with the noise.

• Techniques are all frequency dependant, which impacts frequency response negatively since there is inherent overlap in frequencies between desired speech and undesired background noise. Sometimes speech signals are incorrectly recognized as noise and vice versa.

• Additional constraints: Need processor and power supply

Our Approach is Passive

Noise rejection

Average Noise Rejection

Inside a Blackhawk Helicopter

Summary

• Noise cancelling technology adaptable to different form factors of handsets and headsets (theBoom, theBoom Quiet)

• Noise cancellation technology being used in US Military, Dept. of Homeland Security and Car Racing (UmeCobra)

• Noise-Robust speech recognition applications used on trading floors

• Development of desktop and handheld applications with noise-robust speech recognition capabilities with the help of noise-cancellation technology

Vision of the Future

The freedom to communicate wherever you are and the ability to whisper and be heard.

www.umevoice.com