Natural Science Forum / Physics / Acoustics / September 2007

Hi List,
I am planning to build a fake was to reduce noise transmission from my
noisy neighbour.
Mainly voices and TV.  Luckly not loud music - yet......

Does a Helmholz resonator have to be round and have it's port in the centre?
Is round(cylindrical) the most efficient shape?
Would putting a resonator on both sides of a speaker double the spl?
anybody?

How does ultrasound do this?
Quotes from http://en.wikipedia.org/wiki/Virtual_reality :
“On April 7, 2005, Sony went public with the information that they had
filed for and received a patent for the idea of the non-invasive beaming

Because of many inquires about the possible use of ultrasound for
different purposes I have decided to create a web site, that lists all
such cases. On this web site I will try to arrange in keywords all
know cases of use of ultrasound in science and technology. As far as I

Can anyone tell me how to calculate attenuation with distance
accurately. I am looking at a line source (i.e. a road) radiating up
to a window in a block of flats. I have measure the noise on the
carriageway side but need to model for a height on 7.5 metres. I

I am trying to understand how wolf eliminators work when a weight is
attached to the string length between the bridge and tailpiece of a cello
(the weight is vibrating as part of the string).  The behavior of this
string is more complicated that a simple vibrating string.  I have ...

Assume that there is a bead suspending in the water, and a sound
signal at certain frequency is conducted into the water.  I guess the
bead will vibrate with the same frequency. If so, can anybody tell me
how to estimate the amplitude of the vibration? thanks a million!

Assume that there is a bead suspending in the water, and a sound
signal at certain frequency is conducted into the water.  I guess the
bead will vibrate with the same frequency. If so, can anybody tell me
how to estimate the amplitude of the vibration? thanks a million!

As we discussed in a past post, acoustic metal roof decks are tested
sitting over several inches of high density fiberglass in the test
chamber.  In reality, they are installed with hard insulation board
(generally poly-isocyanurate) on top, not fiberglass.  I have proposed

Here are the plans I'm using: http://www.ehhs.cmich.edu/~dhavlena/bk.gif
Does anybody know of a formula based on volume of the box that will give me
the optimal bass response?  I want it to sound like an upright acoustic
bass, as much as possible.  Don't know if this is the forum ...

dear Friends:
I need to measure the acoustic door FSTC
on Jobsite. the building have 6 acoustic doors in conference room .
the acoustic doors area is 4m2.

Just ended up with a roll of some kind of leaded vinyl, got
to be over 50 lbs. I have used another product for speaker boxes before, but
is this stuff any good for walls, or should I toss it into the earth?
greg

    Perhaps someone knows here:
    In the area of automatic controls, or active noise & vibration control,
savants usually mirgate their analysis to condider a "Plant".
    Now you can imagine my confusion, since I know it is not a thing that

Hello! I am trying to figure something out. If I record the sound of a
car revving up its engine at a location near an interstate where
traffic is constant, would there be a way to subtract the ambient
noise due to the passing cars on the interest?