Piezo Wall Paper for Force Balance Noise Cancellation

[Bret Cahill]

Rooms or houses in neighborhoods located near practice aircraft
carrier runways contend with after burner jet noise. While new
building codes require builders to use passive sound proofing
materials it would be better to have an active system that turns on
when the outside noise exceeds a limit and/or at the flip of a switch.

Piezo would allow for much lower voltages than capacitors.

Sandwich piezo electric material between the 2 outer most layers of a
panel. If this doesn't provide enough power to drive the piezo
material in the 2 innermost panels in the reverse direction -- same
expansion or contraction -- then the output of the outer panel may be
amplified to whatever level is necessary to hold the innermost panel
still.

It may be more effective to break the panel into a lot of independent
areas. Three or more layers may be more cheaper and/or more effective
than just 2.


Bret Cahill

 

[HardySpicer]

On Sep 25, 4:43 am, Bret Cahill <Bret_E_Cah...@yahoo.com> wrote:

Rooms or houses in neighborhoods located near practice aircraft
carrier runways contend with after burner jet noise.  While new
building codes require builders to use passive sound proofing
materials it would be better to have an active system that turns on
when the outside noise exceeds a limit and/or at the flip of a switch.

Piezo would allow for much lower voltages than capacitors.

Sandwich piezo electric material between the 2 outer most layers of a
panel.  If this doesn't provide enough power to drive the piezo
material in the 2 innermost panels in the reverse direction -- same
expansion or contraction -- then the output of the outer panel may be
amplified to whatever level is necessary to hold the innermost panel
still.

It may be more effective to break the panel into a lot of independent
areas.  Three or more layers may be more cheaper and/or more effective
than just 2.

Bret Cahill

No it wouldn't. Plus, it wouldn't work very well at all.

 

[Bob Masta]

On Sat, 24 Sep 2011 08:43:54 -0700 (PDT), Bret Cahill
<Bret_E_Cahill@yahoo.com> wrote:

Rooms or houses in neighborhoods located near practice aircraft
carrier runways contend with after burner jet noise. While new
building codes require builders to use passive sound proofing
materials it would be better to have an active system that turns on
when the outside noise exceeds a limit and/or at the flip of a switch.

Piezo would allow for much lower voltages than capacitors.

I don't know about that! You may have noticed that piezo
speakers are always tweeters. That's because high
frequencies don't require much volume displacement. If you
try to generate low frequencies, you'll run into
displacement problems with the "thin film" piezo material.

Industrial piezo drivers that I have seen are ceramic tubes,
driven via a voltage on each end so the tube expands
longitudinally. They require hundreds of volts to get
millimeters of displacement.

In general, you can generate loud low-frequency sound via
lots of small low-displacement drivers moving in phase. But
for this application, each driver has to be able to cancel
the unwanted sound impinging on it, and it alone. It can't
rely on contributions from it neighbors, since they will
have the same needs.

Best regards,


Bob Masta

DAQARTA v6.02
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!

 

[Bret Cahill]

Rooms or houses in neighborhoods located near practice aircraft
carrier runways contend with after burner jet noise.  While new
building codes require builders to use passive sound proofing
materials it would be better to have an active system that turns on
when the outside noise exceeds a limit and/or at the flip of a switch.

Piezo would allow for much lower voltages than capacitors.

I don't know about that!  You may have noticed that piezo
speakers are always tweeters.  That's because high
frequencies don't require much volume displacement.  If you
try to generate low frequencies, you'll run into
displacement problems with the "thin film" piezo material.  

Enough layers ought to get the required displacement.

Industrial piezo drivers that I have seen are ceramic tubes,
driven via a voltage on each end so the tube expands
longitudinally.  They require hundreds of volts to get
millimeters of displacement.

Without the numbers to compare piezo to caps it's hard to say but 500
V sounds better than 5 kV.

Was that for a speaker? As you mentioned on the cap thread just
holding something still doesn't require linearity.

There are all kinds of piezo materials. We need the one that,

1. has the highest expansion-contraction / voltage coefficient, and,

2. costs the same as gypsum board.

In general, you can generate loud low-frequency sound via
lots of small low-displacement drivers moving in phase.  

Producing multiple layers might not be all that more expensive than
just 2 or 3 layers.

One advantage to the piezo panel is, if necessary, it could be printed
like any MEMs device to have tens of thousands of independent "mics"
and negative speakers at a tiny fraction of the cost of other systems.

They produce 12 mega pixel cameras for $40 so this ought to be duck
soup.

But
for this application, each driver has to be able to cancel
the unwanted sound impinging on it, and it alone. It can't
rely on contributions from it neighbors, since they will
have the same needs.

The outer layer(s) receiving the noise would be wired in parallel to
all the subsequent layers, probably with amplification.

I've wandered away from a servo solution but it's hard to ignore the
fact that the mechanical energy in the noise was won at a very high
price. The re heat cycle is horrifingly inefficient. If it is so
difficult to keep the high quality energy from turning into heat
_before_ it becomes sound, how come it so difficult to turn it into
heat _after_ it becomes sound?

It doesn't seem fair.

Best regards,

Bob Masta

              DAQARTA  v6.02
   Data AcQuisition And Real-Time Analysis
             www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
    Frequency Counter, FREE Signal Generator
           Pitch Track, Pitch-to-MIDI
          Science with your sound card!