Klarinet Archive - Posting 000086.txt from 1996/10

From: Leonardo Fuks <leonardo@-----.SE>
Subj: Re: odd comment (acoustics)- CO2
Date: Fri, 4 Oct 1996 12:20:58 -0400

Excuse-me if I am dropping on the list a little late for this discussion, I
could not make use of my net for a whole week.
I am doing research on breathing/blowing habits in reed woodwinds and this
theme interests me a lot.
I have been measuring the CO2 contents in exhaled air during playing the
oboe and I got some preliminary
ideas and data so far :

- The percentage of exhaled air during normal respiration (no instrument
connected to your mouth)
usually ranges from 2.5 % to 3.5 . If you take more time to complete the
exhalation phase, the final amount of CO2 should increase.
- As you start playing (I just measured oboe until now) the percentage of
CO2 raises continuously from the above values and depending on the duration
and remaining air volume in the lungs, being this slope positively
dependant on time (the more-the more) and negatively to instantaneous volume
(the least volume, the fastest the increase of CO2).Values close to 8% were
found while 1 subject (myself) played Schumann's 2nd Romance, during the
long phrases, without circular breathing, of course.
- A measurement with 4 subjects, showed (preliminarly) that if a small flow
of air is produced through a
small opening, at aprox. 30 cm H2O mouth pressure, the maximum bearable
condition corresponded to aprox. 8% in
all of four subjects.
-If you quickly breath in or perform a circular breath, the %CO2 quickly
returns to the low levels.
-The maximum tolerable percentage of CO2, before you faint is of about 10%
according to some sources. Of course you will die if this condition persists...

Well, as I told before, this is just a first glance on the CO2 presence and
I am planing to write a paper on that later on. I will turn to the problem
by the end of the year and would like to keep in touch with the
"green-house effect watchers" in woodwinds.

I used an equipment called "Capnograph", which measures the CO2 content
through the infra-red method. The model used was :
Capnograph , CD-3A Carbon Dioxide Analizer (I don't have the name of the
manufacturer now)

A fresh air for all,
Leonardo

Music Acoustics PhD Programme
Royal Institute of Technology
BOX 70014 , Drottning Kristinasvag 31
S-10044 - Stockholm - SWEDEN