Hi Vicki and Paul--
I think that sound source or stimuli differences could account for
much of it. Paul used pink noise from a speaker 19" from the mic as
the sound source. In my test, the clock is 72" away in the center.
The crow call has passed through a window in the same direction about
200' beyond. The bass and lower mid-range sounds are from a
dehumidifier and fans passing through several, thick walls entering
the test room as very diffuse sound waves. The other harmonic tones
are probably from two ac power "wall warts" 21' away. My test was at
max gain in a very quiet room, so differences in the ways the mic
arrays are responding is not surprising. How the differences get
created is a question that might be worthy of exploring, but another
topic.
I did the another test outside with the same set-ups at full gain
with a din of insects. I'll take a listen to this in consideration of
the high Hz response difference Paul's test produced.
Paul, can you describe the boundary you used in more detail? One of
us could try to duplicate your results. Rob D.
=3D =3D =3D
At 5:46 PM +1000 7/16/10, vickipowys wrote:
>
>
>I agree, this is difficult! Rob's demo has one clip with more low
>frequencies than the other, while Paul's demo has one clip (free)
>with more high frequencies than the other. So I am "baffled" :-)
>
>Vicki
>
>On 16/07/2010, at 4:01 PM, hartogj wrote:
>
>> That is a tough one, Rob. There is definitely a shift in qualities
>> between the two, but one does not seem to have 6dB less noise than
>> the other. That may be because the subject clock and crow are on
>> axis to the mic capsule in both, where I would expect the biggest
>> difference would be for sounds the boundary itself is facing. I'm
>> going to guess that A is on the boundary, because it sounds like
>> the barrier shadows some of the higher frequency content heard in
>> B. Even with 50% chance to get it right, I bet I am wrong.
>>
>> John Hartog
>>
>>
>>>
>>> <http://tinyurl.com/28aqxkw>http://tinyurl.com/28aqxkw
>>>
>>> Which is the boundary mic arrangement and which is open air? Is
>>> there a significant difference in self-noise performance? Is there
>>> "awful comb filtering" in one sample that is not in the other?
>>>
> >
> >>
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