For directional programs in Aventa, clinicians have the option of adjusting the Directional Mix (or crossover frequency) between omnidirectional and directional processing. Why and when would they want to do this?
The Directional Mix in Aventa software sets the point at which frequencies will be processed as either omni-directional or directional through split-band directionality. Split-band directionality is incorporated into all of ReSound’s directional technology, and separates or splits frequencies for directionality according to what the normal, unaided outer ear does. Low frequencies are processed in an omni-drectional mode, with directionality in the higher frequencies. Directional Mix settings are calculated automatically based on the individual patient’s hearing thresholds and the model of hearing instrument. In typical clinical practice, it is seldom necessary to make changes to this setting.
Increasing the “Directional Mix” setting results in shifting the crossover frequency to allow more low frequencies to be processed in the directional beam. This typically results in an increase to overall loudness or loudness perception for the directional beam. Some people find it easier to think of this increase to the Directional Mix as a “Bass boost” for directionality, however it is important to note that ReSound instruments do not roll off low frequencies in the directional mode. Rather, low frequencies are intact but processed in an omni-directional mode similar to the normal ear.
By increasing the directional mix setting, more low and mid frequencies are pulled into the directional beam. If a patient complains of persistent difficulty understanding conversation in noisy surroundings or hearing the person speaking from the front, the Directional Mix setting can be increased as a possible solution. If the patient complains that the hearing instrument is too noisy in quiet situations, the Directional Mix setting can be decreased.