Ask the Audiologist

Phonak Claro™

The Phonak Claro™ digital signal processing hearing aid is one of the first multi-channel digital aids from the scientists who brought us the AudioZoom™ directional microphone hearing aids. The challenge for the Phonak scientists was to come up with an improvement on the very successful AudioZoom™. They believe they have done it.

The feature that distinguishes the Claro™ from all of those that came before it is its Digital Perception Processing™, or DPP for short. DPP will take a little explaining to make it understandable, so let’s step back a little.

The satellite TV industry, along with anyone who needs to send a lot of bandwidth over a limited bandwidth channel, needs to get rid of all unnecessary information. One such bandwidth reducing technique contained in the MPEG (Motion Pictures Experts Group) encoding technique, is to throw away any signals that would not be used by the receiver. In the case of sound, the ultimate receiver is the human hearing system. One little known fact about our hearing is that louder, low frequency sounds mask, or cover up, quieter higher frequency sounds. This means, that the timpani can cover up the violins, or rather, do cover up the violins, when the sound levels and frequencies are right. The MPEG coding system leaves out the violins during the “boom” from the timpani. It does this continuously, dropping information whenever it is not needed. The MPEG standard can achieve tremendous savings in bandwidth and is widely used by the video and audio industries.


Phonak illustration
What does this have to do with hearing aids, you ask? Well, many of the newer hearing aids are able to boost low amplitude sounds to make them audible, even when you have a substantial hearing loss. Since these sounds are boosted to your “comfortable listening level”, independently of each other in some multiple frequency band hearing aids, you may find that some sounds that you would hear with normal ears, will be masked by those boosted quieter sounds. This may make it harder to understand in some situations than it would be with the older simpler hearing aids.

Phonak noticed this effect and applied a processing technique that makes sure that lower, quieter sounds, don’t get amplified up enough to interfere with louder sounds that you would normally hear. This Digital Perception Processing™ is applied in 20 overlapping frequency bands. This controls the perceived loudness rather than the amplitude of each frequency band. Because of the very large number of bands, broad band signals are correctly amplified and not summed up to fool the hearing aid gain control circuits.

But there’s more to the Claro™. Like several other digital signal processing hearing aid circuits, the Claro™ can tell the difference between speech and non-speech signals. Claro's Fine-Scale Noise Canceler™ analyzes the signals in each of the 20 frequency bands, automatically reducing gain in the bands where a poor speech to noise ratio is detected, and leaving it alone in other frequency bands. Also, the noise canceler makes allowances for where the noise is and applies less gain reduction at those frequencies important for speech understanding. Thus, if you have a narrow band noise signal, the Claro™ circuits can reduce its amplitude without bothering the other nearby frequencies.

Remember the Phonak AudioZoom™ hearing aid, with its dual microphones? Well, the Claro™ also has dual microphones in those models with enough exposed surface area for the proper spacing of the microphones (not in the Canal or Completely in the Canal models). This time, however, the antenna patterns of the microphone array can be digitally adjusted for maximum usefulness in noisy situations. These adaptive digital array patterns are automatically adjusted to locate the loudest noise source and suppress it.

Claro™ applies these signal processing tricks on the incoming signal one at a time for maximum effect. First it applies the Adaptive digital AudioZoom to reduce the noise coming into the circuitry. Then it uses the Fine-Scale Noise canceler to reduce the gain of those frequency bands where noise is present. Then it applies the Digital Perception Processing to amplify just those bands needed to provide adequate sound levels for the hearing aid user, without upward frequency masking.

So, what if you don’t want all this intelligent stuff happening while you are in a concert and not trying to carry on a conversation with someone? The Claro™ has user controls, either a push button on the case, or a small remote control. The Claro™ has four programs: QuietAdapt, NoiseAdapt, AutoSelect, and telephone coil. It is expected that most users would operate the Claro™ in the AutoSelect mode most of the time. The Claro™ BTE instruments also have a volume control, although it is not expected that the user would adjust the volume very often.

Phonak Photo The Hearing Center Photo

A remote control is not required to operate these Claro™ hearing aids, but it is available as an option. The remote can adjust volume and change programs on both ears simultaneously. The remote control is not necessary to operate the hearing aids, so you can leave it home when you don’t plan to use it. A wrist watch version of the remote control is also available. It comes in two men's versions and two women's versions.

Phonak Photo

The Claro is available in all styles from CIC to BTE, including a Power version.

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