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Requirements for Acoustic Echo Cancellation and Noise Reduction

VOCAL’s acoustic echo cancellation (AEC) and noise reduction (NR) algorithms are well suited for noisy environments, such as automobile, transportation or healthcare ¬†environments. Road noise, engine noise and wind noise and other noise sources can make communication uncomfortable for the remote party. The noise reduction techniques used by VOCAL are very efficient at eliminating these noise sources.

VOCAL has various software modules that significantly improve the audio quality when using in-car audio systems, personal tablets or intercoms. Our noise reduction software can enhance the signal-to-noise ratio of a far distance speaker. In addition, our acoustic echo canceller is robust in high intensity echo environments, and environments in which double-talk detection is difficult. Once the signal-to-noise ratio has been enhanced and the echo signal has been removed, software automatic gain control, parametric equalization, and audio level compression can be used to further improve the overall sound quality of the communication.

One challenge in achieving full-duplex audio in these systems is the acoustic coupling between the loudspeaker and microphone. This creates an echo that is sent back to the remote party. The annoyance level of the echo is a function of the delay and the amount of echo loss. The roundtrip delays are usually at least 100ms. Thus, acoustic echo cancellers need to achieve at least 35 dB worth of attenuation, in order for the quality of the communication to become acceptable.

One acoustic environment that presents some obstacles are intercom systems in healthcare settings. In these environments, the near-end talker is far away (distances greater than 6 feet) from the microphone and loudspeaker. This distance creates two problems. First, the signal-to-noise ratio for the near-end speaker is low. The second, loudspeaker signal, is often amplified so it can be heard clearly from a distance. This high intensity loudspeaker signal creates a larger intensity acoustic echo in the microphone signal. The combination of these two problems creates a low near-end to echo ratio, which makes achieving full-duplex audio a difficult problem because during periods of doubletalk the echo signal signal swamps the near-end signal.

Contact us to discuss your specific requirements for voice quality enhancement; our team of engineers have the experience and expertise to develop a solution that will meet your telecommunications needs.

More Information

VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Amherst New York 14228
Phone: +1-716-688-4675
Fax: +1-716-639-0713
Email: sales@vocal.com