- In this video, I'm talking about that static hiss
that you might be hearing inside of your hearing aids,
and what a feature called expansion can do about it,
coming up.
(upbeat music)
Hi, guys, Cliff Olson, Doctor of Audiology
and founder of Applied Hearing Solutions in Phoenix, Arizona
and on this channel I cover a bunch
of hearing-related information
to help make you a better informed consumer.
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make sure you hit that subscribe button
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Hearing aids are specifically designed to amplify things
that you want to hear like speech and music
or some other desirable sounds
like birds chirping or a baby laughing.
However, hearing aids can also inadvertently
over-amplify certain soft sounds
that you don't necessarily want to hear
like the drone of the refrigerator
or the washing machine or the air conditioner
and even the circuit noise of the hearing aid itself.
And this is often perceived as a hissing sound
and this hissing sound can be perceived
for a variety of different reasons.
First is your residual hearing ability.
The likelihood that you will actually hear this static hiss
depends a lot on what your low-frequency hearing is like.
Take a look at this audiogram.
Most individuals with presbycusis
or age-related hearing loss have good low-frequency hearing,
but bad high-frequency hearing.
The better your low-frequency hearing ability,
the greater the likelihood
that you will perceive this static hiss,
because your hearing is already sensitive
to softer level sounds in those ranges.
Second, is the use of compression.
Now compression is used for two different reasons.
Number one is to reduce the amount of amplification
given to really loud sounds
to make them more comfortable for you,
and to increase the amount of amplification
given to soft sounds to make them audible to you.
Now you can get a more detailed understanding
of what compression is by watching my compression video
that I will link in the description of this video,
but sometimes compression can actually over amplify some
of these softer sounds that you may not want to hear.
And the third factor is how quiet your environment is.
If you happen to be in a very quiet room
and the only thing running is your air conditioner,
there's no other types of sounds
that can mask over your perception
of that soft-level amplification,
which means that you'll perceive it even more.
Now if you're hearing that static hiss,
there are a few things that can be done to get rid of it.
The first thing that you can do is just adapt to it.
Over time your brain tends to get used
to certain levels of input,
and once it determines that that input
is not necessarily important,
it has the ability to start tuning it out
to the point where it doesn't even distract you anymore.
Second is reducing the amount of amplification
that the hearing aids are giving you.
If you actually turn down the amount
of amplification overall in the hearing aid,
of course it's also going to reduce down the amount
of amplification that's given to these softer sounds.
Now I don't typically recommend this,
even though this is probably one of the main ways
that a hearing care professional will reduce the amount
of static hiss that you hear,
because it can actually reduce down your audibility
for these soft level sounds that you do want to hear,
like someone who's talking really softly to you.
The third approach to reducing this hissing sound
is enabling a feature called expansion.
Now expansion is a lot like compression
only instead of where compression increases the amount
of amplification given to softer level sounds,
expansion actually reduces the amount
of amplification given to softer level sounds.
Now soft level speech tends to hover around 50 to 55 dB SPL,
which you absolutely wanna make sure
that you're amplifying appropriately
with the use of compression to make sure
that the soft speech is audible to you.
The problem like I mentioned before is
that compression can have the unintended consequence
of over-amplifying these other soft level sounds
like the refrigerator or the air conditioner
or your circuit noise inside of your hearing aid,
that is, unless you use expansion.
With expansion we can program a hearing aid
to give less amplification to these really soft level sounds
and here's an example of how to do this
inside of the programming software for Phonak Hearing Aids.
With the expansion feature, we can reduce the amount
of amplification given to 35 dB SPL inputs
by increasing the Threshold Kneepoint,
otherwise known as TK, at specific frequency ranges.
This typically takes away that hissing sound
without negatively impacting soft level speech
that is in that 50 to 55 decibel range
that I mentioned before.
Now here's another example of how to use expansion
inside of the programming software for ReSound Hearing Aids.
ReSound gives mild, medium,
and strong expansion setting options
which reduce amplification given to soft sounds
at varying levels of reduction.
The stronger the setting,
the less amplification is given to soft level sounds.
The higher levels of technology allow for a greater range
of reduction using expansion
while the lower levels of technology only allow
for a small reduction to these soft level sounds.
Overall, having a deep understanding
of how expansion works isn't necessarily critical,
as long as your hearing care professional
knows how to use it, knows how to implement it correctly,
and you have hearing aids
that actually give it as an option.
So if you are having the perception of this static hiss
in a quiet environment and you can't get used to it,
then expansion is the feature that you're looking for.
That's it for this video,
if you have any questions
leave them in the comments section below.
If you like the video, please share it,
and if you wanna see other videos just like this one,
go ahead and hit that subscribe button.
Also feel free to check out my website drcliffaud.com.
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