Getting Rid of Noise with a Cochlear Implant

A few posts ago we talked a bit about what sound and noise are. Noise can be a big issue for any listener and especially for someone with a cochlear implant.

In that article about noise, we briefly mentioned some of the ways that an audio processor can make it easier to hear in noisy situations. Now, we’ll go into depth about what these are and what they mean for a MED-EL cochlear implant recipient.

Getting Over Noise

Quick recap: Noise is any sound that you as a listener don’t want to hear. The same sound could be considered both noise and not noise, depending on the context. Do you want to hear the wind blowing through the autumn leaves? Then, in this situation, the wind would be not-noise. Do you want to avoid hearing the wind as you ride in the car? Then, in this situation, the wind would be noise.

If you’ve got a cochlear implant, this applies to you just as it would for someone with natural hearing. Your audio processor’s microphone will still pick up the sounds in your environment, and your brain will still try to gauge what you’re interested in and what you want to hear.

Your brain has a natural ability to focus in on the sounds you want to hear; this is something called “listener intent.” Just like the brain of someone with normal hearing, your brain does a lot of work to determine what you want to hear—and to help you hear this better.¹

Reducing Noises with Your Audio Processor

Your brain is amazing at focusing in on the sounds you want to hear. That’s why it’s important that your audio processor gives your brain as much sound as possible, so that your brain can do what it does best: thinking.

Your audio processor can’t and shouldn’t think for you. If it works too hard to reduce sounds that it thinks are noise, then this can keep you from hearing the sounds you want to hear.

This doesn’t mean an audio processor is totally useless at filtering out a certain amount of noise. Right now, there are two ways that a processor can help your brain to reduce unwanted noise: Wind Noise Reduction, and Microphone Directionality.

Wind Noise Reduction

Wind Noise Reduction concentrates on lowering the ‘buzz’ sound of wind passing over your audio processor’s microphone. It uses software algorithms to figure out if you’re in an environment where there’s wind that could make it harder to hear other sounds. Almost all wind creates sound in a specific frequency range, so the algorithm focusses in on this specific range of sound. Then, it slightly reduces the volume of any sound in this range—usually the sounds of wind. This doesn’t completely turn off the wind, but it can make it easier to hear the sounds you want to hear like voices or music.

Microphone Directionality

Microphone directionality is another way that your audio processor can help zero in on the sounds you want to hear. It works by using the SONNET Audio Processor’s two microphones to listen in one of three specific patterns:

• Omni, which picks up sounds equally from all directions
• Natural, which focusses on sounds to the front just like the human pinna does
• Adaptive, which adapts to help focus on sounds to the front by reducing the volume of sounds that are behind you or to the side of you

A study of 10 SONNET users compared the natural and omni modes, and found that the natural mode leads to significant improvement in hearing when there was noise behind the listener.² That means that instead of picking up all the sound, including the noise behind you, it focusses on the sounds that come from where you’re looking and lowers the volume of those that are behind you.

What You Can Do

But like we said, an audio processor can’t know what your brain is thinking. That’s why there are also some behavioral ways to focus in on the sounds you want to hear. Largely, they have to do with that bit about listener intent we talked about above.

Pay Attention

Paying attention to what you’re listening to has been shown to enhance brain activity and can lead to better understanding.³

At the same time, you don’t need to always stare at whoever’s speaking. Another study found that following a speaker’s gaze can help listeners to better understand what’s being said;⁴ seeing what’s being talked about makes it easier for your brain to make sense of the sounds it’s hearing.

Reduce the Noise

Background noise isn’t always inevitable. There are lots of ways that you can reduce or even eliminate common background noises:

• Turn off the TV, or appliances like dishwashers, if they’re distracting
• Move closer to whoever is speaking to you
• Close the windows to block out sound from the outside
• Close the room’s door if someone outside is is making noise.

Hear Your Best

Cochlear implants are amazing bits of technology, and your brain is an amazing bit of biology. When they work together, you can help overcome the noise that gets in the way of hearing your world.

References

1. Moberly A.C., Lowenstein J.H., Nittrouer S. (2015). Word Recognition Variability With Cochlear Implants: “Perceptual Attention” Versus “Auditory Sensitivity”. Ear Hear, [Epub ahead of print].
2. Wimmer, W., Weder, S., Caversaccio, M., Kompis, M. (2015). Speech Intelligibility in Noise With A Pinna Effect Imitating Cochlear Implant Processor. Otol Neurotol, [Epub ahead of print].
3. Schröger E., Marzecová A., SanMiguel I. (2015). Attention and prediction in human audition: a lesson from cognitive psychophysiology. Eur J Neurosci, 41(5):641-64. doi: 10.1111/ejn.12816.
4. Staudte M., Crocker M.W, Heloir A., Kipp M. (2014). The influence of speaker gaze on listener comprehension: contrasting visual versus intentional accounts. Cognition, 133(1):317-28. doi: 10.1016/j.cognition.2014.06.003.