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y8s 05-17-2015 08:52 PM


Originally Posted by triple88a (Post 1231984)
So i want to use my computers speakers and microphone to lower the noise in my room. Any ideas on software that does that?

Basically i'm looking for a program that will use the microphone to record the sound, invert it 180 degrees and play it again through the speakers.

It doesn't really work that way. There's circuitry involved that does noise cancellation. It also has some specific tuning requirements to make it work in a room rather than, say, right on your ears or in a car where the factory made it work.

I guess you can look for "noise cancellation software" and hope you have some luck.

Joe Perez 05-17-2015 09:32 PM


Originally Posted by y8s (Post 1232190)
It doesn't really work that way. There's circuitry involved that does noise cancellation. It also has some specific tuning requirements to make it work in a room rather than, say, right on your ears or in a car where the factory made it work.

^ This.

Noise-cancelling headphones work because:
  • The spatial relationship between the microphone, the speaker and your ear is fixed, and
  • There aren't a lot of surfaces inside the headphone cup for the sound to bounce around off of.

In a room, you might be able to tune the system so as to achieve cancellation at one particular spot, but then as soon as you moved, not only would the cancellation cease to be effective, you'd start hearing echoes as well.

sixshooter 05-18-2015 07:58 AM

Naturally aspirated 944's were fairly high compression and required premium fuel and were knock limited with regard to spark timing without forced induction. I don't recall what the metering and timing system behind the Bosch fuel injection was. The timing belt had a short interval for changing and also drove the counter-rotating balance shafts beneath the crankshaft, which made it difficult to replace and tough to time properly, from what little I can recall.

shuiend 05-18-2015 08:36 AM


Originally Posted by sixshooter (Post 1232269)
Naturally aspirated 944's were fairly high compression and required premium fuel and were knock limited with regard to spark timing without forced induction. I don't recall what the metering and timing system behind the Bosch fuel injection was. The timing belt had a short interval for changing and also drove the counter-rotating balance shafts beneath the crankshaft, which made it difficult to replace and tough to time properly, from what little I can recall.

Interesting to know.. Unfortunately the add was deleted by the time I got some free time on Sunday and was about to shoot the guy an email. So I guess I am sticking with miatas for a while longer.

Joe Perez 05-18-2015 10:09 AM

1 Attachment(s)

Originally Posted by sixshooter (Post 1232269)
I don't recall what the metering and timing system behind the Bosch fuel injection was.

Motronic DME, which used a distributor and a mechanical AFM like the 1.6 NA.

https://www.miataturbo.net/attachmen...ine=1431958142


From what I understand, later models incorporated a knock sensor.

triple88a 05-18-2015 06:35 PM


Originally Posted by Joe Perez (Post 1232195)
In a room, you might be able to tune the system so as to achieve cancellation at one particular spot, but then as soon as you moved, not only would the cancellation cease to be effective, you'd start hearing echoes as well.

Well yeah the plan is to have it cancel the noise at the microphone. Microphone being right behind me on the chair.

Enginerd 05-18-2015 11:53 PM

2 Attachment(s)
Speaking of 944's:

1988 GTR Widebody PORSCHE 944 LS1 v8 conversion
1988 GTR Widebody PORSCHE 944 LS1 v8 conversion - $34000

https://www.miataturbo.net/attachmen...ine=1432007603
https://www.miataturbo.net/attachmen...ine=1432007603

deezums 05-19-2015 12:04 AM

Am I the only one slightly really disturbed by the Porsche, in toyota badge script, across what looks like goat valve covers?

I'd still drive it.

18psi 05-19-2015 12:15 AM


Originally Posted by shuiend (Post 1232068)
All this makes perfect sense. Really I am considering it because it would be a nice change from a miata. Would not be looking to sink a ton of money into it, but if I could get 1000-2000 miles of driving out of the 944 over the next year or two I would consider the venture a success. I have AAA so if it does die on my I can get it towed home no problem. Looking up timing belt and water pump kits on eBay show they are about twice the price of the miata, which honestly is not to bad. A friend of mine in NoVA has a 87 944 and he told me if I can work on the miata, I can work on the 944 with no problem. He also said at that price if it does shit the bed, parting it out would be feasible and should be able to make back the cost of the car.

So the follow up question is how well do they take to boost? Is it the same motor that is used by the 944Turbo? If I was to install a MS3X, modern injectors, one of the many turbos I have sitting around, would it put a shit eating grin on my face?

as opposed to getting one of your very many miata's finally completely sorted and enjoy that?

I mean if you were like me and changed cars every couple months, I'd say go for it, but you hoarded a whole fleet of miata's, and now sound like you don't even want em anymore?

shuiend 05-19-2015 09:06 AM


Originally Posted by 18psi (Post 1232559)
as opposed to getting one of your very many miata's finally completely sorted and enjoy that?

I mean if you were like me and changed cars every couple months, I'd say go for it, but you hoarded a whole fleet of miata's, and now sound like you don't even want em anymore?

I am planning on working on my personal miata's as soon as I am done with my group buy. I should have everything ready to do 2 motor swaps and get the 2 newest miatas I have bought back on the road. It is just a time thing. Once I have them going my 92 with 336k will be used even less. So besides needing it to do 1.6 setups on, I don't have a large reason to keep it. So if I found an interesting trade I would not be opposed to it.

y8s 05-20-2015 01:22 PM


Originally Posted by triple88a (Post 1232493)
Well yeah the plan is to have it cancel the noise at the microphone. Microphone being right behind me on the chair.

If you hold your head still and the mic still then you could tune it probably, but the software is complicated. Maybe something like BruteFIR can do it. You might need a second computer to run it.

The critical thing here is that the distance from the speakers to your mic / head is going to be a problem because the speed of sound is relatively slow compared to your ability to differentiate sounds that are out of phase.

For low frequencies where the wavelengths are measured in feet it might work out ok. For high frequencies, where wavelengths are an inch or less, you're just as likely to get constructive interference as you are destructive interference.

mgeoffriau 05-20-2015 04:27 PM

I'm completely discouraged about working on my Miata in the carport. I want an enclosed garage so bad. I'm tired of having to clean up everything at the end of every day, or having the wind blow dust and crap into my work, or dealing with mosquitoes or wasps or gnats.

rleete 05-20-2015 05:47 PM

ShelterLogic Shed - In - A - Box at Blain's Farm & Fleet

I put one up around the hot tub in October of 2013, and it's been up since. Plenty roomy for the tub, but may be a bit of a squeeze for working on a car.

triple88a 05-20-2015 09:17 PM


Originally Posted by y8s (Post 1233140)
If you hold your head still and the mic still then you could tune it probably, but the software is complicated. Maybe something like BruteFIR can do it. You might need a second computer to run it.

Thats the thing i dont get. A tiny littl echip in headphones can do it but for some reason a computer program cant? I'm also looking for whatever spectrum i can get, no need for full range noise cancelation.

Joe Perez 05-20-2015 09:24 PM

[QUOTE=triple88a;1233314]Thats the thing i dont get. A tiny littl echip in headphones can do it but for some reason a computer program cant?/QUOTE]

The tiny little chip in the headphones has a very easy job. The spatial relationship between the mics, the speakers and your ears is fixed, there's only a few cm of distance between them, and there aren't any obstacles in the path for sound to reflect off of. Most of the difficult math has been done ahead of time during the design of the headphones.

Doing this same job in a large open space, with variable distances between everything and lots of surfaces for sound to reflect off of is many orders of magnitude more complex.

Schuyler 05-20-2015 11:13 PM

How about my bank did a hard inquiry when I opened a savings account? Since when is that a thing?

deezums 05-20-2015 11:29 PM

Bank of America tagged me with chexsystems with "account abuse" with a outstanding balance of 0, or something along those lines.

They won't tell me why it's there, all I know is I closed an empty account with them, they won't remove it, and I can't bank as freely as I'd like since lots of them use chexsystems.

Banks do what they want.

sixshooter 05-21-2015 06:59 AM

LOL at using the #1 worst bank in the country for customer service, and then complaining about customer service.

1. Find a local-ish bank with good customer service
2. get better rates on EVERYTHING
3. ????? (wait for it)
4. profit! (no, really. Actual profit!)

Erat 05-21-2015 07:58 AM

The only thing that pissed me off about BoA is that they had like 4 branches within a 5 mile radius of me, now they have one.

It's a complete zoo. It's always packed. It has 3 ATMs and for some reason there is usually always a line of people for each one.

Godless Commie 05-21-2015 08:05 AM


Originally Posted by triple88a (Post 1233314)
Thats the thing i dont get. A tiny littl echip in headphones can do it but for some reason a computer program cant? I'm also looking for whatever spectrum i can get, no need for full range noise cancelation.

The tiny chip in the headset has to deal with whatever sound may find its way into a closed, insulated chamber (that chamber would be that tiny space between your ear and the headphone speaker element surface).
Please keep in mind the fact that those bits of noise will be stripped of their extreme frequencies as they penetrate the insulation. Actual noise is a crapload of different frequencies. The less the better.
Oh, and they will not bounce around the headphone chamber like kids on sugar treats due to soft and rounded surfaces, as well.

In an open environment like a room, the noise will be dynamic. Frequencies of all sorts, bouncing off whatever they can find...

Noise cancellation is creating nodal lines (physics 101). That is the only way, unless you eliminate the noise source. Creating nodal lines for each and every frequency is, well, holy fuck...
Getting the nodal line to move to a desired location is entirely possible in a lab, under controlled conditions, with a single wavelength, and with no (undesirable) echoes.
Change one of these parameters, and you need a much bigger lab, built and funded by Bill Gates's life savings.

Noise cancellation is not turning the sound off in a given environment, rather, it is the creation of certain "quiet spots" within a given volume.
And, you need as few variables as possible in that environment to even talk about the possibility of a successful outcome.


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