Software options for Tuning

**nubz69** · 11-14-2006, 05:44 PM

There is no need for a second computer. There is a need for a relatively powerful computer. I was able to run multiple plug ins as well as VSTi's on my old 1ghz AMD computer. What we are talking about here is very feasible with todays technology. I would post more of what I know here but I am moving to FL in Jan so I have very little time right now. I feel there are more then one way to achieve our goal. The questing I am pondering now is whither we should go about this project as an all in one solution (OS,media player,tuning,GPS) or should we attack this by adding to and modifying existing techniques? I feel the former would work better in the end but I feel that to truly make it would we would need to use a Linux based OS. The latter could work with windows or linux.

**Abmolech** · 11-14-2006, 09:23 PM

There are several reasons I decided to use a car pc for processing duties.

One of which is to do non-linear volume control off a single point. The idea is to maintain "C" weighting at any dB.

Is there a VST plugin available?

**durwood** · 11-15-2006, 07:41 AM

One of which is to do non-linear volume control off a single point. The idea is to maintain "C" weighting at any dB

Could you elaborate why you want to use "c-weighting" over "a-weighting". Do you have any proof that the volume control used by the computer/program uses "a-weighting"?

BTW: I am not using the computer to do my volume control at the moment, but I will be hopefully in the future.

**Abmolech** · 11-15-2006, 11:13 AM

Most volume controls are "linear". Sure your pentameter is logarithmic, however so is dB rating.

Let us assume we set our system for "perfect" volume listening at a certain dB.
As soon as we change this dB (move the volume knob) then we start to move away from the "perfect" listening weighting.

http://hyperphysics.phy-astr.gsu.edu...nd/eqloud.html

The above site is quite good on human hearing. If you observe the loudness curves you will appreciate the different requirements and dB. The "standard" is 1000 Hz, as you change this dB notice the upper and lower frequency dB requirements deviate from the original point.

"C" weighting approximates these settings. (supposedly if you set your RTA microphone on this, you should aim for a "flat response")

How important is this?
I believe dB differences are the primary reason for a system sounding better/worse. In-fact I will go as far to say this THE main criteria for discerning difference between various electronic components. If they are level matched it is very difficult for human hearing to pick variations in most electronic equipment.

This loudness curve is the primary reason for the eq "smiley face" and peoples eternal fiddling with it. I suspect if this was setup to maintain this curve then much less "tuning" would be the result.

**durwood** · 11-15-2006, 11:58 AM

The reason I am bringing this up is that in SQ contests there is a section for linerarity at different volume levels. I had problems in this area at lower volumes. My volume control was adjusted using an Audiocontrol Master Volume control. It was a totally analog volume control. My guess is that it was linear.

I am interested in what you are saying because it could prove to be useful, but when you say "maintain c weighting" is that "c-weighting" to measuring equipment, or to the human ear (which is really a-weighting)? So you want a system that adjusts for equal loudness or basically alters the resposne based on the "Fletcher-Munson curve"? Am I understanding you correctly?

The problem you run into is that human hearing differs from measuring equipment. When they speak of C-weighting is good for home theater applications, then it goes against how we listen. How often do we listen at high volumes? Just because it has flat response doesn't always mean it sounds good all the time. Help me out here.

**Abmolech** · 11-15-2006, 09:12 PM

So you want a system that adjusts for equal loudness or basically alters the response based on the "Fletcher-Munson curve"? Am I understanding you correctly?

Quite correct "C" weighted is wrong.

There is a new standard,
http://en.wikipedia.org/wiki/Equal-loudness_contour
http://en.wikipedia.org/wiki/A-weighted

http://www.phys.unsw.edu.au/~jw/hearing.html

I suspect the curve that should now be used is the ITU-R 468 noise weighting.

I contest one of the problems with in car audio is the use of RTA and pink noise.
The idea of pink noise is to have short enough bursts of a given frequency, so that the microphone can "tell" a reflection from the principle wave. The use of pink noise in a car environment is open to interpretation because the bursts are too long. I believe MLS and adjustable pulse type noise may be the solution to obtaining correct measured volume.

**RedGTiVR6** · 11-16-2006, 08:27 AM

RTA is most likely going to be thrown out of competition in IASCA for the coming years...especially after what happened this year at finals.

**durwood** · 11-16-2006, 10:34 AM

Good riddins. I have never competed in IASCA where they used the RTA but I don't think it makes much sense in a car.

I think it would be cool if they could come up with some other type of measuring using something closer to a "real human". I worked for some time at a hearing transducer company that worked with these "dummy heads". They were similar to the Bruel and Kjaer.

http://www.bksv.com/4071.asp

**Abmolech** · 11-16-2006, 11:21 AM

Probably getting too off topic...

Most software programs for audio are designed for far field listening, including the various theories of acoustic manipulation. Put these into a car situation and most ideas, programs will be sub par. It is interesting reading on headphone acoustics because they face similar problems as us, that is the sound recording was/is designed on two monitors, and requires reproduction in a similar situation to produce the results.

I am not suggesting you throw out all room acoustic theory etc, however most of it is not applicable to a car environment.

Near field listening is a much under-studied acoustic field.

**durwood** · 11-16-2006, 11:32 AM

I am not suggesting you throw out all room acoustic theory etc, however most of it is not applicable to a car environment.

If only home stereo/theater people would try to understand this rather than brush off car people. Then maybe it would be studied more. This is a tad off topic but I think in the long run it will help us find/generate more ideas for software tuning...or human hearing in general. Hell...more understanding lead to all this music compression formats...not that it was good for sound quality but makes putting a carputer in more logical for other reasons.

Added: We need some studio engineers in here. They would be very helpful as far as near-field listening.