The concept was used for the Shadow, marketed by
Threshold under the Phantom Acoustics label.
Worked pretty well, but was poorly understood and
expensive.
pass/ - still got a pair of those.
Threshold under the Phantom Acoustics label.
Worked pretty well, but was poorly understood and
expensive.
pass/ - still got a pair of those.
The same principle is used in noise cancelling Safety Ear Muffs to null out constant machine noise, but enable the user to hear some calling for them.
Hey, if your Misses nags repeatedly these would be handy
Ian
Hey, if your Misses nags repeatedly these would be handy
Ian
This principle is also heavily researched and implemented in various forms in road noise reduction techniques in the automotive industry.
Rodd Yamashita
Rodd Yamashita
It was also the reason behind the NEXT panel speaker, it was developed by the British MOD for noise cancelling in helicopter cockpits.
ANTIPHASE.
Hi,
It would be interesting to use this to cancel room resonances amongst other things.
Maybe Nelson would be so kind as to shed some light on how Treshold implemented this interesting theory.
Cheers, 😉
Hi,
It would be interesting to use this to cancel room resonances amongst other things.
Maybe Nelson would be so kind as to shed some light on how Treshold implemented this interesting theory.
Cheers, 😉
Phantom Acoustics!
I ran those beasties for a trial run years ago! Nelson's right, they were pretty amazing. Actually on par with the cost of RPG or similar baffling of the listening room. I liked them, and they did look very cool.
It played tricks on the mind to shut them down and note the subtle differences! I think such a device is the ticket for difficult situations.
The Pacific Symphony Orchestra benefitted immensely from this method (active suppression) in the fitting of the OC Performing Arts Center. Before it, I was being bombarded with stray reflections...actually nasty like a pair of those Bose thingies hanging from the ceiling.
(I think some die hard fans might get their feathers ruffled at that...but I experimented for weeks with those things. Give me a proper array of speakers any day...like a set of Rushmores to sit with!)
Bob
I ran those beasties for a trial run years ago! Nelson's right, they were pretty amazing. Actually on par with the cost of RPG or similar baffling of the listening room. I liked them, and they did look very cool.
It played tricks on the mind to shut them down and note the subtle differences! I think such a device is the ticket for difficult situations.
The Pacific Symphony Orchestra benefitted immensely from this method (active suppression) in the fitting of the OC Performing Arts Center. Before it, I was being bombarded with stray reflections...actually nasty like a pair of those Bose thingies hanging from the ceiling.
(I think some die hard fans might get their feathers ruffled at that...but I experimented for weeks with those things. Give me a proper array of speakers any day...like a set of Rushmores to sit with!)Bob
An April Fool's Day joke. Amazing.
It's worth noting that we are talking about 2 different
approaches. The standard noise cancelling stuff used
in industry and headphones is generally done by digital
circuitry and is used to remove repetitive waves by analyzing
them with DSP and creating their opposites. This doesn't
work with non-repetitive signals. It's great for noise
reduction, but not suitable for music.
The acoustic feedback as described by Olson and used in
the Shadow is direct: microphone to amplifier to speaker,
and works on instantaneous signals. It's great for audio,
but not as effective for noise reduction.
The patent cover page for the Shadow can be seen at the
www.passlabs.com web site. You can get the full text and
drawing version elsewhere.
By the way, it may be that the original concept was from
Arthur C. Clarke, in his story "Silence Please" / Tales from
the White Hart
pass/ - listening to Zappa's "The Orange County Lumber Truck"
of which he has 4 versions.
approaches. The standard noise cancelling stuff used
in industry and headphones is generally done by digital
circuitry and is used to remove repetitive waves by analyzing
them with DSP and creating their opposites. This doesn't
work with non-repetitive signals. It's great for noise
reduction, but not suitable for music.
The acoustic feedback as described by Olson and used in
the Shadow is direct: microphone to amplifier to speaker,
and works on instantaneous signals. It's great for audio,
but not as effective for noise reduction.
The patent cover page for the Shadow can be seen at the
www.passlabs.com web site. You can get the full text and
drawing version elsewhere.
By the way, it may be that the original concept was from
Arthur C. Clarke, in his story "Silence Please" / Tales from
the White Hart
pass/ - listening to Zappa's "The Orange County Lumber Truck"
of which he has 4 versions.
Zappa - isn't he dead in cancer
Seems some Persons are hard to Silence.
My Father died 2000 - also in prostate cancer. Rest in Peace!
An Example of Zappa's Ironcal Lyrics
Oh God I am the American dream
I do not think I'm too extreme
An' I'm a handsome sonofabitch
I'm gonna get a good job 'n' be real rich
-----------------------
Oh God I am the American dream
---- censored ---------
And my name is Bobby Brown
Watch me now, I'm goin down,
And my name is Bobby Brown
Watch me now, I'm goin down
/halo - not "Goin Down" - yet
Zappa - isn't he dead in cancer? 😱
Seems some Persons are hard to Silence.
My Father died 2000 - also in prostate cancer. Rest in Peace!
An Example of Zappa's Ironcal Lyrics
Oh God I am the American dream
I do not think I'm too extreme
An' I'm a handsome sonofabitch
I'm gonna get a good job 'n' be real rich
-----------------------
Oh God I am the American dream
---- censored ---------
And my name is Bobby Brown
Watch me now, I'm goin down,
And my name is Bobby Brown
Watch me now, I'm goin down
/halo - not "Goin Down" - yet
Re: Zappa - isn't he dead in cancer
Sad it is... he has place of honour in my LP collection (an entire milk crate for himself...
Going to Montana soon, going to be a dental floss tycoon...
dave
planet10/has many Zappa records
halojoy said:
Sad it is... he has place of honour in my LP collection (an entire milk crate for himself...
Going to Montana soon, going to be a dental floss tycoon...
dave
planet10/has many Zappa records
You could use a differential amplifier like an opamp and in the case
of a helicopter pilot you could have a small microphone on the
helmut that picks up the noise and goes through one half of the
opamp and the voice signal going through the other, which also
contains the same noise and the output will be the voice
minus the noise. Common mode rejection.
of a helicopter pilot you could have a small microphone on the
helmut that picks up the noise and goes through one half of the
opamp and the voice signal going through the other, which also
contains the same noise and the output will be the voice
minus the noise. Common mode rejection.
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