dB SPL testing

[Barry Schaede <barrys@xxxxxxxxxxxxxxxxxxxxxxx>]

Apples and oranges.  A valved vs an unvalved diatonic. I have valved 
diatonics too, so I figured why not try one of those.  My test results were 
achieved by blowing a harmonica repeatedly to establish an average level 
then soaking the same harmonica and doing the same thing.  I used a Radio 
Shack sound level meter.  I used the A weighted scale and my range was 
set to 90dB.  I also had the response set to slow. Using the number 10 
blow hole I was unable to detect any significant difference in dB SBL 
between a wet unvalved diatonic and a dry unvalved diatonic.  In both 
instances the average reading was 92 dB SPL and the peak was 94 dB SPL.  
The unvalved diatonic I was using was a key of A Hohner Big River.   
On to the valved Suzuki I used for the experiment.  This time the key was 
D and the hole was the number 5 blow.  Again the same results.  the only 
difference I noted was that wet the harmonica seemed to rise to the peak 
earlier but that the effect diminished in the first 5 seconds or so.  I 
did these tests for an extended period of time.  5 minutes or so.  (my 
ears are still ringing) As Rick has already so sagely pointed out the 
results are subject to variation due to the pressure of breath used to 
blow the note.  Another thing I'd like to point out is that the dB meters 
on tape recorders bear little or no resemblance to a common standard.  
It's a lot like gas gauges.  A quarter tank  in my car might mean 150 
miles to go and in yours it might mean pull over and buy gas now.  
Certainly they have relevance on the particular tape recorder being used 
at the moment.  Does that mean that 5dB is really 5dB?  Maybe, but 
probably not. I'd accept an assertion that the rise time of a wet 
harmonica is quicker in the initial 5 or 10 seconds of its use.  I can 
find no evidence of my own that the actual peak is louder or that the 
effect is sustainable.  BTW I have no particular attachment to either 
result.  My motive is simply inquiry.  FJM