Technology

One, two, three …analog-to-digital converters

Not one, not two, but three analog-to-digital converters (ADCs) in a hearing aid give listeners access to speech via a remote Roger microphone while the hearing aid remains in directional mode. Naida B has three ADCs. Here is the story.

It was a full force delegation. Matthias Latzl (Clinical Research Manager at Phonak), Bernadette Fulton, (Audiology Manager for Severe to Profound Hearing Losses) and I went to Oldenburg in the north of Germany in January 2016. We would see Dr. Kirsten Wagener and Dr. Matthias Vormann of the Hörzentrum Oldenburg, a world-class facility for audiological research. We had a plan, or better put, we needed a plan. That was the plan. To make a plan.

Step one – make listening difficult

It was all about one of the most challenging listening situations imaginable. What makes listening difficult? Noise! So, we had that. A lot of it, coming from 8 loudspeakers in the room. What else? Distance! For that, we placed a loudspeaker generating speech signals at 6.4 meters from the listener. Just a loudspeaker, so no lipreading or other visual cues. But how could we make it really difficult? What is the icing on the cake of audiology?… If another person starts talking at the same time! Don’t you hate that? I do. So we added another loudspeaker generating more speech at 1.4 meters from the listener.

It was all about quite common situations actually — Someone on stage gives a lecture and a member of the audience nearby makes a comment…The best man gives a funny speech and your partner at your table adds comments to the jokes….A colleague presents results at a meeting and another colleague next to you gives his judgment to the data. For normal hearing persons, it is impossible to fully trace all simultaneous audio-streams, but with some luck you pick up something of both. How is that in noise? How is that if you have a severe hearing loss? How is that if you use the latest hearing technology? We wanted to find that out.

Step two – bridge the gap, remove the noise

It was all about the combination of the best products and technology from Phonak. For the remote talker, you need a Roger microphone to bridge the gap in distance and take out the noise. But for the talker close by, you would need the most trusted power hearing aids, Naída, with directional microphones. Now, almost all hearing aids on the market do not support the combination of using a remote microphone for the distant speakers and directional microphones for the near speakers. For that you need three analog-to-digital convertors (ADCs) in the hardware of the hearing aid. The remote microphone signal needs one ADC, and for a beam former in the hearing aid you need two omnidirectional microphones in the hearing aid, each with its own ADC, to create a beam. That makes three ADCs in total. That is not standard hardware. In Phonak Naída hearing aids, we have three ADCs, the feature is called Roger and directional.

Step three – define an innovative test

It was a full day with Kirsten and Matthias, defining a new innovative test, set-up how to measure the audiological performance of such a hearing system in a controlled and repeatable way. This test would entail something other than having listeners repeat back words in a test booth. One of the decisions we made was to investigate speech intelligibility using a dual task test paradigm, where the tasks were presented from either the near field or the far-field loudspeaker. The primary task, identifying a name in a sentence, and secondary task, repeating a full sentence, were presented simultaneously with background noise. This was a dynamic set-up. Luckily, we had kale for lunch, a typical northern German and Dutch winter dish. It gave us energy.

Findings – more than we imagined

It was rewarding to see that a group of 15 listeners with severe hearing loss could perform the task and performed significantly better with Naída’s directional mode than omnidirectional mode. The third ADC pays off. Surprisingly, the directional microphone in the hearing aid also improved speech perception for the distant speaker transmitted to the Naída via Roger. This improvement occurs because the directional microphones in the Naída hearing aids provide further noise suppression.

It is published now, we are happy to share our findings in a peer-reviewed publication. Now you know a bit the history behind it all.

 

 

And if you would like to watch Dr. Cliff Olson’s review of Naída hearing aids, his video is below.

Previous comments
  1. This is fantastic, and particularly inspiring as the listeners in the study had severe hearing loss. Thanks for sharing.

  2. Actually, Hans, this statement is only partially correct:
    For that you need three analog-to-digital convertors (ADCs) in the hardware of the hearing aid. The remote microphone signal needs one ADC, and for a beam former in the hearing aid you need two omnidirectional microphones in the hearing aid, each with its own ADC, to create a beam. That makes three ADCs in total. That is not standard hardware. In Phonak Naída hearing aids, we have three ADCs, the feature is called Roger and directional.

    The Roger Pen has two ADC’s for it’s directional mic, so the article should be titled “One, two, three, four …analog-to-digital converters.”

    The Roger Select has six ADC’s, so the title should be “One, two, three, four, five, six, seven, eight …analog-to-digital converters.”

    But Wait, There’s More!
    There are also three ADC’s for the gyros for the orientation sensor (roll, pitch, yaw), and three more for the accelerometers!

    Tallying all that up, we have 10 ADC’s for the Naida+Roger Pen and 14 for the Naida+Roger Select!

    Isn’t engineering fun?!

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