How the Phone Clip+ Helps You To Not Annoy People On The Phone

J-GrothBy Jennifer Groth

Back in January, I posted here on how the Phone Clip+ provides much improved sound quality over its predecessor for the listener on the far end of the call. To review, the Phone Clip+ provides excellent noise reduction so that the voice quality for the call recipient is clear and pleasant even when the hearing instrument wearer is in noisy surroundings, like in the car. Since then, there have been numerous questions about how that noise reduction actually works. Are we applying NoiseTracker II noise reduction? Is it our Adaptive Directional algorithm? Did we drop in something from our colleagues at Jabra? The answer to all these questions is no.

The engineers at ReSound developed a new noise reduction algorithm specifically for outgoing calls from the Phone Clip+. This noise reduction method requires two microphones, which the original Phone Clip does not have. Well-known (at least in the engineering world) adaptive filtering techniques are used to subtract the noise from the output of the front microphone1.

This noise reduction algorithm makes the assumption that the front microphone picks up both the signal of interest, which in this case is the voice of the hearing aid user, and the interfering background noise. A further assumption is that the rear microphone only picks up the interfering noise. Then, adaptive filtering is applied to make the noise from the rear microphone equivalent to the noise from the front microphone. This filtered noise is subtracted from the front microphone signal, leaving a clear signal of interest.

Obviously, the assumption that the rear microphone only picks up noise is not true. The way this issue is solved is by estimating direction of arrival of sounds, similarly to what directional hearing aids are able to do. Using this information, the filter applied to the rear microphone noise is only updated in the frequency bands where sound is estimated to come from the rear. As a consequence, the filter can “tune in” to noise sources from the rear and remove them, but leave signal sources from the front intact.

We have already reported on the perceptual improvements for call recipients with Phone Clip+, but what is the measured improvement in signal-to-noise ratio? This was tested by placing a phone accessory (Phone Clip, Phone Clip+ with and without noise reduction, and other manufacturer’s streamer) on a Head and Torso Simulator (HATS) in the position a hearing aid user would wear it. The HATS includes a speaker in the mouth of the manikin which can be used to present the signal-of-interest. The HATS was placed in varying noise backgrounds, and the signal received from the phone accessory by a Bluetooth compatible device was analyzed at a remote location from the test room. The following graph shows results for “Pub noise” background noise.

SNRBluetooth

First of all, it is obvious that any of the noise reduction processing provided by the devices tested provided a signal-to-noise ratio benefit compared to no noise reduction. However, the Phone Clip+ provided an additional 3 dB improvement in SNR over both the Phone Clip as well as another manufacturer’s streamer.

Wireless streaming of the phone signal to both ears has been shown to be an unbeatable way for hearing instrument users to hear on the phone2. But phone calls are two-way communication. It’s not much help if you can hear the person you are calling but they can’t hear you well. The Phone Clip+ takes the benefit of a phone accessory a step further by ensuring the best possible quality for the person on the other end of the call.

REFERENCES

  1. Haykin S. Adaptive Filter Theory, 4th edition. Prentice Hall, New Jersey, 2002.
  2. Picou E, Ricketts T. Efficacy of hearing aid based telephone strategies for listeners with moderate-to-severe hearing loss. Ear & Hearing 2013; 24:59-70.
This entry was posted in Noise & Feedback, ReSound Newsletter, Sound Quality and tagged , , . Bookmark the permalink.

15 Responses to How the Phone Clip+ Helps You To Not Annoy People On The Phone

  1. Pingback: Hearing Aids Made for iPhone – guest post by Jennifer Groth | A.U. Bankaitis's Audiology Blog

  2. Edward says:

    Helpful article to me as knowing how something is designed to work, helps me work with the device in a way that might maximize its usefulness. In this regard, the mic on the back is critical to the noise cancelling strategy, where is it located? In certain noisy environments, I wonder whether a good strategy (though not necessarily a convenient one) would be to hand hold the PC+ at about chin level and orient the back of the device toward the source of the ambient noise? Also, I had one person I called who complained that they heard an echo of their own voice, but this disappeared when I disconnected the PC+ and just continued the call on iPhone. Not sure that the PC+ had anything to do with this, and it has not recurred with same person or with different calls, however I have only had the PC+ a few days and am making peace with the device.

    • gnresound says:

      Hi Edward, both the mics are on the front on the Phone Clip+. When you are wearing the Phone Clip+ as intended, the microphone ports will be oriented correctly to cancel ambient noise. Please let us know if you have any other questions!

  3. Steve Ranner says:

    I like the sound of this phone clip+
    Not sure if it’s available via the VA (Who supplied my hearing aids)
    Are they available to purchase from an independent supplier?

    • gnresound says:

      Hi Steve, the ReSound Phone Clip+ is available through the VA so you can definitely ask your audiologists there about it. If you have additional questions, please let us know!

  4. Steve Ranner says:

    Many thanks, will check them out.

  5. Divinea Almoradie says:

    Hi, I have a Clearsounds Qh2 bluetooth phone amplifier connected to my work phone, but it will not pair with my Linx aids. Do I need the Phone Clip to be able to stream directly to my Hearing aids? If not, what do I need to stream my workphone to my Hearing aids?

    • gnresound says:

      Hi Divinea, According to product reviews for this particular Bluetooth hub it appears that people have been using it and the Phone Clip+ together successfully. We have not been able to test this particular device officially for compatibility but we have seen the Phone Clip+ pair with similar products. Your ReSound LiNX hearing aids will connect directly to iPhone, iPod and iPod touch for direct audio streaming. You will need a PhoneClip+ to stream to any other Bluetooth phone. If you have any further questions please feel free to contact our Consumer Technical Support Team by email at consumersupport@gnresound.com or by phone at 1-888-735-4327 and press option 1.

  6. Hiya, I have Danalogic Ifit CS71 aids and a Phone clip+. I have no trouble getting both aids paired but I can only actually get audio through one side – It only plays through whichever one pairs first. I’ve tried doing them at exactly the same time but one always comes out ahead. Any suggestions? Thanks, Michele

  7. mridland says:

    Additionally, I can’t work out how to make an outbound call on my Bluetooth enabled landline phone – I can take incoming calls but not make outbound ones – am I missing something?
    Thanks,
    Michele

  8. mridland says:

    I have Danalogic Ifit CS71 hearing aids and a PhoneClip+. I can pair both aids at the same time but only get audio through one at a time, which one depends on which one was paired first. I’ve tried pairing them at the same time but one always comes out ahead. I’ve tried with audio from my landline, mobile and with an audio book and it’s always the same. Any recommendations?
    Thanks,
    Michele

  9. Luc LEDENT says:

    Hello, I have been using phone clip and phone clip + for many years with different handsets: not problem at all, it definitely improved my life. Recently, the company where I am working switched to ShoreTel systems and I was given a IP 8830 M handset with BT functionalities. Impossible to pair it with the Phone Clip + while I had never experienced any problem with any handset so far. Is Phone Clip + compatible with this device ? Do we need an accessory ? Who could help ?
    Many thanks in advance

    • gnresound says:

      Hi Luc, thank you for contacting ReSound. The IP address of your post is indicating you’re located in Belgium. This blog is monitored by the US subsidiary of ReSound. We recommend contacting our Global Headquarters in Denmark at phone number +45 4575 1111 to ensure you get accurate information.

      • Luc LEDENT says:

        Can you give me an e-mail address for the customer service in DK, it is easier for me to communicate in writing

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