DFS™ digital feedback suppression

Role
Reduces feedback while preserving amplification without compromising sound quality.

End user benefit
User is not bothered by feedback or by sudden reduction of volume, which some other hearing aids do to prevent feedback.

When feedback is detected, a phase-inverted signal is applied, which cancels out the whistling. ReSound’s DFS applies two individual control systems that work together to provide maximum comfort with feedback-free hearing.

Static control

The system analyzes the calibration signal during fitting and neutralizes feedback with a static control signal. This accounts for the unchanging contributors to feedback such as venting, ear geometry, and hearing aid components.

Dynamic control

The dynamic control system includes two parts. One is a dynamic filter that changes to eliminate feedback via phase cancellation when wearing the hearing aids. In extreme situations where the feedback cancellation may be overwhelmed, dynamic gain restoration layers on top to ensure comfortable listening.

Dual Stabilizer II DFS with Whistle Control

Feedback suppression system follows the same principle as the DFS Ultra, but with simpler algorithms.

Auto DFS

This DFS option learns the feedback path of the individual to efficiently cancel feedback. Whistle Control is not built in to Auto DFS.

Whistle Control

As part of the dynamic control system, Whistle Control is used only in extreme cases, when DSF alone cannot cancel feedback completely. In such cases, it lowers the gain to the prescribed level of frequencies affected by feedback until feedback is eliminated.

Music Mode

Music is typically difficult for feedback cancellation systems to process, as it is difficult to distinguish true feedback from other tonal input sounds. Music Mode uses the same processing as DFS Ultra II, but slows down feedback cancellation to ensure that tonal sounds are not adversely affected. Rich sound quality for music is preserved.

DFS OVERVIEW
SETTING	AUTO DFS	ADVANCED DETECTION ALGORITHM	WHISTLE CONTROL	MUSIC MODE
DFS UltraTM II	*	*	*	*
DFS UltraTM		*	*
Dual StabilizerTM II			*

RESOUND MODEL	TYPE OF DFS	SETTING
LiNX Quattro 9, LiNX Quattro 7, LiNX Quattro 5 / LiNX 3D 9, LiNX 3D 7, LiNX 3D 5 / ENZO² 9, ENZO² 7, ENZO² 5 / ENZO 3D 9, ENZO 3D 7, ENZO 3D 5 / Up Smart 9, Up Smart 7, Up Smart 5	DFS Ultra™ II	Mild, Moderate, Strong, Music mode
Enya 4, Enya 3 / Magna 4	DFS Ultra™ II	Mild, Moderate, Strong
Enya 2	DFS Ultra™ II	On
Magna 2	Dual Stabilizer™ II DFS	On

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