On Mar 11, 1:38*am, (Adrian
Tuddenham) wrote:
Robert Macy wrote:
Need a sound recorder for recording noise intrusion from an adjacent
tenant.

Using Sony ICD-SX700 did not achieve very good results.

What should I use?

The recorder isn't as important as the microphone and the playback
loudspeaker. *

Is the noise coming through in one place (e.g. hammer drilling or tap
dancing) or is it diffuse? *If it is diffuse, an omnidirectional mic
might work best.

If the noise is predominantly low frequency (e.g. boom box) a cheap
omnidirectional mic will generally have a better low frequency response
than a cheap cardioid. *The big problem you will have with L.F. noise is
demonstrating it realistically to someone, because loudspeakers are
rarely flat at such frequencies and the bass from headphones will depend
on their positioning on the listener's ears.

Investment in a cheap analogue sound level meter will help; then you can
calibrate the recording level and match the playback level to it when
you come to demonstrate the problem. *Use the dBC scale if the noise is
predominantly L.F.

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)www.poppyrecords.co.uk

Thank you for your reply. Curious, why dBC, not dBA?

The sounds are being transferred through above tenant's flooring and
then through our ceiling. It is possible to tell origin, but it's
like a spotlight diffused onto a sheet of paper - you can tell where
it's coming from a little.

I like the idea of calibrating to verify the recorded sound
presentation recreates EXACTLY what was there, but may be difficult in
a large courtroom...

Any recommendations for readily available sound level meters? the
Sony has vu meters on it, but I think they're relative and not
absolute.

I did notice that the low level sounds using this mike/preamp of the
Sony appear to be sitting around the last 5 to 10 levels of
digitization. I did a 'quiet' recording and was going to do a
histogram to find out. But there was just enough room noise to
prevent that. there's a spike around 100Hz and a lesser one again
near 200Hz, but don't know where that's coming from. Too high for air/
fan noise? two PC's in the room were running. on 60Hz mains.

Naive question: does quantization cause hiss? only distortion?

Not sure, but removing the low frequency spikes the noise spectral
density does appear reasonably flat, except for the what appears as 1/
f noise starting to come up around 50Hz, but who hears that, right?

Robert