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NoiseTracker™ II 

The goal of fitting prescriptions is to provide amplification for optimum speech understanding while ensuring comfort for loud sounds. Even if achieved for a particular individual, this would not take into account that the wearer might want to enhance or diminish different aspects of the amplified sound in different situations.

The combination of NoiseTracker™ II and Environmental Optimizer™ II in ReSound's newest hearing aids solve this issue.

Individually tailored adaptive noise reduction 

The Environmental Optimizer™ II allows for seamless changes to hearing aid function in order for the user to adapt to the many listening situations one could potentially encounter. Although situation dependent preferences for both volume and noise reduction have been demonstrated15,16, clinical experience with environmentally dependent changes in hearing instrument settings indicates that wearers prefer changes in hearing instrument settings to be small and gradual for acoustically similar environments.


However, in the many cases where the environment does not clearly fall into one category or when the environment rapidly changes, an algorithm steers the volume and NoiseTracker II settings to a continuously changing linear combination of the prescribed settings for the three most probable categories.

Because of the hearing aid’s continuous ability to access combinations of classifications, gradual behind the scenes changes to the hearing instrument function allow for the wearer to experience transparent sound transitions.

NoiseTracker II
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Unique use of spectral subtraction 

Environmentally dependent noise reduction settings make little sense unless the algorithm offers benefit in environments where speech is present. The NoiseTracker II system uses spectral subtraction17, one of the most widely used methods for enhancement of noisy speech in audio applications. The concept of spectral subtraction is to subtract the short-term noise spectrum from the total signal, leaving only the speech portion. Although the concept is easy, the implementation is not. The success of this strategy hinges on being able to identify speech and to precisely characterize noise. An additional challenge is to keep up with the dynamic speech and noise make-up of real listening environments. Finally, it is important for hearing instrument users that not all noise be removed from the signal, and that the noise characteristics be preserved. If all ambient noise were removed or if the spectrum of the noise background was altered, this would create an unnatural-sounding experience. Background sounds do need to be audible to the degree that users can recognize and orient themselves in their listening environments. Ultimately, the goal is undistorted speech at the prescribed gain, and undistorted noise at lower gain.