Sound cancellation technology?

Iffin eye 'member ritely, methinks i mentioned using DSPs (in opera houses and other sound stages)...

Well, a bedroom *is* slightly smaller than an opera house or airplane...

Naw..it is Gold Rueberg.

Which is why i suggested conductive pickups outside and conductive speakers/vibrators inside.

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If you can arrange things so that you sleep in a 4" Y-shaped pipe with a speaker on one leg and all of the undesired noise entering at the other leg, then it will work. Try your experiment with a one foot square box with a handful of speakers outside the box sending noise - different sources - through the box walls. (Put a microphone inside so you can tell how noisy it is.) Now try to reduce the noise with any configuration of speakers inside the box.

No they haven't.

Systems have been built in large halls to *add* reverberation, with the halls designed to start out with dead acoustics.

You cannot remove reverberation of echos using active cancellation. That can only be done with passive sound absorbers and passive helmholtz resonators.

And what happens when the listener changes position, say, rolls over or gets out of bed? What if there are two listeners? Implant transmitters in their craniums and track realtime position in 3D, adjust DSP to fit?

A pair of soft earplugs might be a -trifle- easier solution. Or better windows. Or insulation. Or moving out of the 'hood and into the 'burbs, like the rest of middle-class.

Try the active sleeping ingredient in Bacardi.

Basically undoable.

Get extra glazing installed.

Graham

As a sound engineer amongst my various skills, please note you're talking out of your arse.

Graham

You can only do it for a single point in the room ( and even that's pushing it ). Room reverberation and the indivual source locations make the concept unrealisable.

Extra glazing by comparision works and is inexpensive.

A car cabin is a much smaller environment than a room. Some success can be acheived. Lotus did a lot of early work on this but I don't think it ever went into production. I have no idea why Mercedes bothered though. The cabin in my Saab for comparison is so quiet that I find the 'tick' of the brake light relay intrusive !

They do ? You can get noise cancelling headsets ( easy to do ) but I'd like to see a link to any further use.

Graham

Considered triple glazing ?

Increasing the thickness / weight of the glass is hugely effective too. My windows are single glazed but with 6mm laminatated glass. Made an astonishing difference over the old windows.

If it's coming through the walls that's not good. What's your wall construction ?

Graham

It could only happen in the USA ! Lol ! Do they fit machine guns too on request ?

Graham

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Films on the glass could be used to reduce light, UV or for security.

Films can also stop vibrations of a glass window, like puting a finger on a pitch fork.

Films between two layers of glass or glass and plastic create an air space that acts as a buffer for the sound. The films also resonate at different frecuencies as the glass windows. They dissipate sound wave energy or they shift sound frequencies to frequencies that you can not hear.

That's fine if what you want to do is to stop a glass window from vibrating. What is being discussed is reducing the amount of sound being transmitted through a glass window, and no plastic film can possibly do that.

...has what appears to be a good design, but the web page tells lies about "stopping vibrations - like a finger on a tuning fork." If you tap your window with a rubber hammer and it rings like a bell, such dampening will help. Most windows are already well-damped by the frame. You will note that soundproofwindows.com doesn't try to sell you single-pane laminated glass for soundproofing - becuase they know that it lets as much sound through as normal glass when placed in ordinary window frames.

No it doesn't. *Air* between two layers of glass or glass and plastic creates an air space that reduces sound transmission.

Bullshit. No acoustical treatment can shift sound frequencies to frequencies that you can not hear.

Try accumulating some sleep debt.

I used to know someone who worked for Nelson Mufflers. In addition to making normal mufflers, they were also getting into sound cancellation. I had the impression from him that it ws doable, but expensive and that you could make it as quiet as you wanted, but that the weight and price went up as you demended more quiet.

In your case, where you just need the cancellation at the head of your bed (a single person?) that might not be too hard/expensive.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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With all due respect to the my esteemed colleague, I know of no evidence of anyone removing reverberation or echos using active cancellation. It may be that there is a technology that I am unaware of, but I rather suspect that no such technology exists.

You can design a directional speaker system that puts less energy into the reverberant field, or use a filter to put less energy into frequencies that reverberate especially well in a particular room. You can even amplify early reflections and thus mask some of the reverberation. What you cannot do is remove reverberation with any sort of active cancellation. Once energy is put into the reverberant field it can only be passively absorbed.

I should add that I believe it is also true that it is easier/cheaper at lower frequencies (longer wavelengths.)

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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