Frequently
Asked Questions
Dear Sir
Let me introduse myself - my name is Radovan Wiecek and
I work in Czech Metrology Institute (CMI), Brno, Czech
Republic, Europe. I'm Director of Regional Branch Brno
and the Head of laboratory of acoustics. More
information http://www.cmi.cz/index.php?act=159&lang=1
(I'm very sorry but it's just in Czech)
Now I'm working at NPL, Teddington, England for 3
months.
I try to compare standards which deal with the backround
noise levels in audiometric test rooms or booths.
In Europe we use standards ISO
8253-1,2 and 3, you
know them.
I've found ANSI S3.1 tables
in your website.
I've found somewhere that in that
"new"
ANSI standard are values for 31.5 Hz and 63Hz and also
for high frequency, above
8000Hz.
May I ask you for sending me of those values?
You
know, there won't be any demands for calibration
according
to ANSI standard in the Czech Rep., so therefore
I do not want to buy this one.
And
I want to finish that comparison this week....
In
the Czech Rep. we measure speech audiometry in the
sound field. And our standard is really very
strict.Especially at the low frequencies.
I'm
very sorry to bother you but I'm very interested in this
field because I'm
preparing some
national regulation for calibration of speech
audiometers. And
one of the most important thing is to measure background
noise.
Thank
you very much in advance
With
best regards
------------------------------------------------------------------
Michael Der replied:
Thank you for your question. I
will do my best to provide you with the information
you requested during the next few days.
Sincerely,
Michael Der
Audiologist
-------------------------------------------------------------------------------
Dear
Michael,
Thank
you for your email.
I
must say your website inspired me to
prepare something similar in my language. It's really
perfect. Very fine job.
Let
me introduce myself a little more. Just very
shortly....
As I
wrote to you yesterday I worked in Czech metrology
institute. Now I'm Director
of
one of internal units. There are many laboratories in my
unit e.g. primary labs of mass,
pressure
and DC voltage with national standards,
temperature, length etc in secondary level.
And
there is acoustic department as well and I'm the head of
this one. It's secondary level laboratory and the main
work is to calibrate audiometers, Artificial Ears,
Mastoids, SLM,
microphones,
filters etc...
Our
laboratory is just one in our country which can provide
calibration of audiometers. (There
is a
law that audiometers have to be calibrated/verified
every 2 years in our lab.)
Now
I'm working at NPL, UK for 3 months to learn
more about calibration of high
frequency
audiometry, short duration signals audiometry, low-noise
background measurement etc.
I'd
like to cooperate with you, discussion, solving some
problems etc. And I want to prepare
Czech
website, similar to yours.
My
question is - may I use some information from your
website, to translate them and
to
use them in my Czech website?
Of
course, If you agree or if it seems to be good idea.
(There will be link to your website
and
acknowledgment and whatever you want.)
What
do you think about it?
Please,
let me know.
------------------------------------------------------------------
Michael Der replied:
Thank you once again for your
positive comments. The calibration website that I
created and administer is actually a project I undertook
when I was in graduate school at the University of Western
Ontario, currently the home of the National Center of
Audiology in Canada.
I think a Czech version of this type
of website would be a good idea if you believe there is an
audience for it. If you could put my link on your
website that would be wonderful. I do not have problem
with you citing my work in your future website,
however, if your site is to become a revenue
generating project, I will need to be informed.
With your permission, I would like to post your
comments and identity on my website so that readers can
see the type of audience I have captured with my
work.
My research and academic background
is more focus on clinical audiology. I am curious to
know why you are undertaking research in low and high
frequency audiometry. The clinical value of
threshold measures at frequencies below 250 and above 8000
Hz can be questionable. In terms of communicative
ability, you can appreciate there are very few sounds in
human speech that will encompass range above 8000 and
below 250 hz and when fitting amplification devices, I
have never seen hearing thresholds above even
6000 Hz to be of much value. Do the laws in
your country require you to do testing at these levels?
Looking at your question from your
previous email, you mentioned an interest in standard
ambient noise levels at 31.5 and 63 Hz. These are
extremely low frequencies to be making measurements
for clinical practice as I'm sure you are aware. You
can appreciate that to sustain a consistent sound
attenuated environment to make measurements at these
low levels, you will need a very very thick walled sound
booth. I have written an article that addresses this
issue in my website: http://members.fortunecity.com/michaelder/absorptive.html
I have been busy at work and I hope
to have a reply to your question later tonight.
Unfortunately, my website is not a revenue generating
project and I do have a full time job outside of my
interests in audiology and acoustics. Although I hesitate
to consider myself an expert in the field of acoustics
and audiology, I do have a significant background and
experience in this field. If you have any
other questions regarding the calibration of audiology and
or acoustic equipment, I will be more than happy to offer
my assistance.
Regards,
Michael Der
Audiologist
--------------------------------------------------------------------------------
Michael Der wrote:,
I do not have the most recent ANSI
3.1 - Maximum Permissible Ambient Noise Levels for
Audiometric Test Rooms. The most recent version is
1999, and i only have 1991, however, both standards should
be very similar. In your previous
question, you inquired about a test zone frequency for
31.5 Hz and 63 Hz. The ANSI standard uses 31.5 and
63 Hz as Octave band and 1/3 octave band interval
measurements and not test frequencies. I have
attached a copy of this in .jpg form for your review.
I am quite certain that the 1999 standard would follow
similar guidelines. As I indicated before, the
clinical value for test measurements at 31.5 Hz is
questionable. I will fax you the entire ansi
3.1 document tomorrow morning.
Sincerely
Michael Der
Audiologist
to view the .jpg file sent to this
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