How does DFS Ultra Feedback Cancellation Affect Telephone Use?

Question

Answer

DFS Ultra is ReSound’s adaptive feedback cancellation system. This advanced system ensures that the feedback path is as accurate as possible for each microphone on the hearing instruments and also places limitations on how much it can adapt to changes in the feedback path.  In situations with large changes in the feedback path, such as holding a phone near the hearing instrument, the system incorporates an additional algorithm, Whistle Control. Whistle Control serves as an additional layer of feedback control by reducing the occurrence of feedback that arises from dynamic, transient situations such as using the telephone. Feedback that manages to elude the cancellation system is controlled via gain equalization instead of gain reduction in the frequency range of the feedback. This means that based on the individual’s target gain curves, gain is equalized to match the target curves to combat feedback in lieu of notching or fast-acting gain cuts at the frequencies of the feedback. The signal itself is unaffected while the feedback spike is equalized, thereby simultaneously maintaining audibility while eliminating feedback.  It is important to note that Whistle Control does not reduce gain below the desired response and therefore does not affect audibility. In effect, DFS Ultra restores or equalizes the correct gain and maintains the sound quality, while eliminating feedback.

For more information on ReSound Verso, visit www.gnresound.com or the ReSound Expo Page on Audiology Online.