Can DSP be programmed to help with my hearing problem ?

Can a DSP system help me? ...  I have been diagnosed with severe tinnitus
(ringing in the ears) and hyperacusis (sensitive to loud noises).  After
attending a play last night with earplugs in to prevent further injury and
pain, and not being able to hear anything anyone was saying, I thought there
must be a better way.

I have some experience with microcontroller programming and with simple
audio circuits and understand the concept of digital processing, but am
certainly not up to speed on it.  This all leads me to ask and start the
research ...

Can a DSP device be programmed to simultaneously provide :  ???
    - Compression - To amplify low level a bit and bring down the high-level
    - Absolute max noise limiting - To protect from further damage
    - white noise generation (2 or 3 seperate, tuneable white-noise
generators would be desired. One way to deal with severe tinnitus is to
"mask" the noise with white noise of matching frequencies, then use sound
augmentation, "a-la-hearing aid" to bring the normal sound up a few db to
make it heard.  These are used long-term in an effort to retrain the ear to
ignore the tinnitus noises.
    - multi-frequency equalization (6 band or so) - to adjust for limited
range hearing damage.

I cannot find a device out there that contains all of these components in a
single headphone and I need to know if I should pursue building my own.  I
have had this problem for many years and it is getting worse, so I don't
mind putting a bunch of time, money and learning into this project to help
myself.

Thank you in advance for any comments, tips, or suggestions you might offer.

Jim
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Jim Frohoff, jfroh_NO_SPAM_@_NO_SPAM_earthlink.net

Jim Frohoff wrote:
> Can a DSP system help me? ...  I have been diagnosed with severe tinnitus
> (ringing in the ears) and hyperacusis (sensitive to loud noises).  After
> attending a play last night with earplugs in to prevent further injury and
> pain, and not being able to hear anything anyone was saying, I thought
> there must be a better way.
>
> I have some experience with microcontroller programming and with simple
> audio circuits and understand the concept of digital processing, but am
> certainly not up to speed on it.  This all leads me to ask and start the
> research ...
>
> Can a DSP device be programmed to simultaneously provide :  ???
>     - Compression - To amplify low level a bit and bring down the
> high-level

Easy.

>     - Absolute max noise limiting - To protect from further damage

Easy - a non-linear version of the above can do this.

>     - white noise generation (2 or 3 seperate, tuneable white-noise
> generators would be desired. One way to deal with severe tinnitus is to
> "mask" the noise with white noise of matching frequencies,

That wouldn't work, since white noise is random.  Hmm, or would your brain
just learn to ignore that frequency band?  If it does, then why can it not
ignore the tinnitus?  My undrstanding of the ear and related systems falls
down here :-)

> then use sound
> augmentation, "a-la-hearing aid" to bring the normal sound up a few db to
> make it heard.  These are used long-term in an effort to retrain the ear
> to ignore the tinnitus noises.

Ahh - I see :-)

>     - multi-frequency equalization (6 band or so) - to adjust for limited
> range hearing damage.

Yep.  This can be easily achieved in the fourier domain.

> I cannot find a device out there that contains all of these components in
> a single headphone and I need to know if I should pursue building my own.
> I have had this problem for many years and it is getting worse, so I don't
> mind putting a bunch of time, money and learning into this project to help

> myself.

I can't see any fundamental problems with this approach - I suspect that the
tweaking to make it just right would be hardest.

Anyway - those in the know will follow this up with more detailed and
positive advice, I suspect.

Ben
-- 
I'm not just a number. To many, I'm known as a String...

"Ben Pope" <spam@hotmail.com> wrote in message
news:blqc2m$f8d15$1@ID-191149.news.uni-berlin.de...
> Jim Frohoff wrote:
> >     - white noise generation (2 or 3 seperate, tuneable white-noise
> > generators would be desired. One way to deal with severe tinnitus is to
> > "mask" the noise with white noise of matching frequencies,
>
> That wouldn't work, since white noise is random.  Hmm, or would your brain
> just learn to ignore that frequency band?  If it does, then why can it not
> ignore the tinnitus?  My undrstanding of the ear and related systems falls
> down here :-)
>

I believe he means that the white noise only needs to be around the
frequency he is trying to mask.  I believe it would be white noise band
passed filtered to the size of what's called a critical band (roughly
1/3-octive) with the center of the band matching the frequency of the ring
he's trying to mask.  This way other sounds of different frequencies aren't
affected anyway near as much.

So I believe the answer is that you need to filter the white noise source to
a tunable bandwidth.  (Filtered 'white noise' I believe is referred to as
'pink noise', but I digress).  This should be very doable.

In general what you're asking for probably couldn't be home-made as a normal
sized hearing aid.

Good Luck.

> That wouldn't work, since white noise is random.  Hmm, or would your brain
> just learn to ignore that frequency band?  If it does, then why can it not
> ignore the tinnitus?  My undrstanding of the ear and related systems falls
> down here :-)

Thanks for the reply -

Here's a ref to TRT treatment for tinnitus that utilizes the white noise
masking : http://www.epleyclinic.com/trt.htm

I have located several references to generating white or pink noise with
DSP, so it looks do-able, though this will obviously be a huge amount of
learning ahead for me.  My guess is that I just create the white noise and
then setup my two or three bandpass filters to let through what I need to
mask the tinnitus frequencies.

Any suggestions to DSP kits / software that come with some of the code
libraries I will need to start learning how to do the compression, limiting,
eq and white noise generation?  I have just spent the afternoon hours
reading everything I can find on the TI dspvillage.com site.

Jim

> I believe he means that the white noise only needs to be around the
> frequency he is trying to mask.

Precisely

> > So I believe the answer is that you need to filter the white noise
source to
> a tunable bandwidth.  (Filtered 'white noise' I believe is referred to as
> 'pink noise', but I digress).

Pink noise has even power distribution per octave.  So I guess what I need
is just a small bandwidth of "random" noise, whether it's pink or white
probably won't matter. I will be doing some testing shortly, but I believe I
only need 1/3 octave centered on the tinnitus frequencies, as you described
above.

> In general what you're asking for probably couldn't be home-made as a
normal
> sized hearing aid.

No doubt impossible for "normal sized" hearing aid.  What I have in mind is
a pocket module that can help make my life a bit more normal again  :-)

> Good Luck.

Thanks, I'll need it.  Jim

Jim Frohoff wrote:

>>I believe he means that the white noise only needs to be around the
>>frequency he is trying to mask.
> 
> 
> Precisely
> 
> 
>>>So I believe the answer is that you need to filter the white noise
> 
> source to
> 
>>a tunable bandwidth.  (Filtered 'white noise' I believe is referred to as
>>'pink noise', but I digress).
> 
> 
> Pink noise has even power distribution per octave.  So I guess what I need
> is just a small bandwidth of "random" noise, whether it's pink or white
> probably won't matter. I will be doing some testing shortly, but I believe I
> only need 1/3 octave centered on the tinnitus frequencies, as you described
> above.
> 
> 
>>In general what you're asking for probably couldn't be home-made as a
> 
> normal
> 
>>sized hearing aid.
> 
> 
> No doubt impossible for "normal sized" hearing aid.  What I have in mind is
> a pocket module that can help make my life a bit more normal again  :-)
> 
> 
>>Good Luck.
> 
> 
> Thanks, I'll need it.  Jim
> 
> 
I think you're on the right track. First make it work, then make it 
pretty. If I wanted to do that -- and one of these days I might -- I'd 
start with a low-power stereo board and headphones that look like 
gun-range ear protectors (and act like them when unpowered), with 
microphones mounted right on them. Once you get it tinkered with enough 
to be worth using, you can power the board from three sealed lead-acid C 
cells at least long enough to enjoy a play or a movie. If you decide 
it's worth doing, you could miniaturize it later. You might want to talk 
to the people at Songbird. They're always looking for new niches for 
their products. If you were one of their guinea pigs, you'd get their 
aids free. If it solved only one of your problems, it could still be 
worth while. http://www.songbirdhearing.com/

Several people who make boards you can use read and post here. I would 
use a 'C33 DSK because I already have one and I don't think it would 
compromise what I could achieve. I like the idea of floating point for 
one-offs and prototypes, even where fixed point might be better in 
production. There are likely to be fewer gotchas for a beginner. If you 
want to break down the design into parts, write about here. You'll get 
plenty of advice, and maybe even a degree of consensus.

Jerry
-- 
"I view the progress of science as ... the slow erosion of the
  tendency to dichotomize."                    Barbara Smuts, U. Mich.
���������������������������������������������������������������������

Jim Frohoff wrote:

>>That wouldn't work, since white noise is random.  Hmm, or would your brain
>>just learn to ignore that frequency band?  If it does, then why can it not
>>ignore the tinnitus?  My undrstanding of the ear and related systems falls
>>down here :-)
> 
> 
> Thanks for the reply -
> 
> Here's a ref to TRT treatment for tinnitus that utilizes the white noise
> masking : http://www.epleyclinic.com/trt.htm
> 
> I have located several references to generating white or pink noise with
> DSP, so it looks do-able, though this will obviously be a huge amount of
> learning ahead for me.  My guess is that I just create the white noise and
> then setup my two or three bandpass filters to let through what I need to
> mask the tinnitus frequencies.
> 
> Any suggestions to DSP kits / software that come with some of the code
> libraries I will need to start learning how to do the compression, limiting,
> eq and white noise generation?  I have just spent the afternoon hours
> reading everything I can find on the TI dspvillage.com site.
> 
> Jim
> 
> 
> 
> 
> 
There are a lot of ways to do this. Analog Devices makes an analog 
volume compressor that has nice features. It can be made to output a 
maximum level without much distortion. A very fast attack time can 
simulate a clipper without generating harmonics the way a clipper does. 
The gain for low levels can be limited, so ambient noise isn't amplified 
to a distracting level. The noise generators can be analog too, and 
summed in, at a point to keep them unaffected by the input level, ot to 
rise and fall with it. You can do all of that with the DSP too, but it 
may not be as easy for you to tweak: you decide. Start with one channel, 
then go DSP stereo once you know what's wanted. It's possible to twist a 
pot while you keep listening. With a reasonable program, you have to 
recompile or at least load a new table to do the same thing, and A-B 
comparison becomes hard.

Jerry
-- 
"I view the progress of science as ... the slow erosion of the
  tendency to dichotomize."                    Barbara Smuts, U. Mich.
���������������������������������������������������������������������

"Jim Frohoff" <jfroh@earthlink.net> wrote in message news:<dl2gb.3523$Qy2.1014@newsread4.news.pas.earthlink.net>...
> Can a DSP system help me? ...  I have been diagnosed with severe tinnitus
> (ringing in the ears) and hyperacusis (sensitive to loud noises).  After
> attending a play last night with earplugs in to prevent further injury and
> pain, and not being able to hear anything anyone was saying, I thought there
> must be a better way.

You could try to talk to some people I know, who have developed an 
active earplug for use in severely noisy environments. 

You find them like this:

- Go to www.sintef.com
- Enter "acoustics" in that search box in the upper righ hand side 
  of the page
- High among the hits (no. two or three this morning) is a link called
  "Advanced hearing protection" or something like that. 

Go to that page, and you can contact the people mentioned there. I am sure 
they would be very helpful in pointing you to resources or references that 
you may find useful. 

Rune

On Mon, 6 Oct 2003 01:13:08 +0100, "Ben Pope" <spam@hotmail.com>
wrote:

>Jim Frohoff wrote:

>>     - white noise generation (2 or 3 seperate, tuneable white-noise
>> generators would be desired. One way to deal with severe tinnitus is to
>> "mask" the noise with white noise of matching frequencies,
>
>That wouldn't work, since white noise is random.  Hmm, or would your brain
>just learn to ignore that frequency band?  If it does, then why can it not
>ignore the tinnitus?  My undrstanding of the ear and related systems falls
>down here :-)

This is one of those areas where the effectiveness of the treatment
depends a lot on the individual, but this sort of thing has been used
with some success on a lot of folks.   It doesn't work for everybody,
and some people do self-mask tinnitus without any training (I fall in
that category, fortunately).

Apparently the noise helps to decorrelate the tinnitus in the brain,
which for some people otherwise locks to it like a PLL and amplifies
it (kinda like the "don't think of a purple elephant" trick).  Once
the brain gets the hint that the tinnitus can be ignored (after it's
masked with noise for a while), it doesn't have as much trouble doing
it.   At least that's my simplified take on what is most likely a very
complex neural processing problem in our wetware.   There are some
well-known Tinnitus researchers who claim to know relative
sensitivities, etc., well enough to know exactly how much noise to
apply, etc.  It's pretty interesting stuff, but the need is real and
this sort of treatment with level-controlled noise in the frequency
region of interest seems to work for a lot of people.


Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

Jim Frohoff wrote:
...
> Can a DSP device be programmed to simultaneously provide :  ???
>     - Compression - To amplify low level a bit and bring down the high-level
>     - Absolute max noise limiting - To protect from further damage
>     - white noise generation (2 or 3 seperate, tuneable white-noise
> generators would be desired. One way to deal with severe tinnitus is to
> "mask" the noise with white noise of matching frequencies, then use sound
> augmentation, "a-la-hearing aid" to bring the normal sound up a few db to
> make it heard.  These are used long-term in an effort to retrain the ear to
> ignore the tinnitus noises.
>     - multi-frequency equalization (6 band or so) - to adjust for limited
> range hearing damage.

Hi Jim,

a while back I toured the production floors of a hearing aid 
manufacturer here in Switzerland (this tour was organized by the local 
section of the AES, the Audio Engineering Society).

They produce devices with microscopic-sized battery-powered 
A/D-DSP-D/A-Amp units (about the size of a chick pea) - unbelievable 
when compared to what we are used to in pro-audio. The DSPs have a fixed 
processing path (something like frequency-crossover, multiband 
compressor, 5-band eq and limiter) with programmable coefficients which 
should cover your points 1, 2 and 4. It is taylor programmed to your 
needs at one of their distributor's lab.

They are also very active in psycho-acoustic research, and each semester 
   they organize, together with University of Zurich, a course in 
psycho-acoustics.

The company's name is Phonak.

Regards,
Andor