Psychoacoustics Fundamentals

[pozz]

How much genuine research has been done into car audio, and where are the relevant web sites? Looking for something beyond what I can find on the sales web sites, but if there are some of the sales sites that have excellent technical info, I would want to know about those also. I have JL Audio systems in both my Jaguar & Camaro.

Both Harman and Bose have done a lot, but I don't know how much of that been published. @hardisj

 

[AudioStudies]

The audio literature makes it clear that large rooms have significant advantages over small rooms with respect to acoustics. It does baffle me a bit though, how good small rooms (and even cars) can sometimes sound. I have a small room (den) in which I use Focal Shape 50s in conjunction with a powered subwoofer. There is a closet in the room with sliding doors. I suspect the closet may be serving as a crude (or maybe not so crude) form of room treatment. Experimenting with various degrees of opening widths of the sliding closet doors seems to help for this room, and the closet is not really being used for clothes, but I have shelves built with LP and CD storage in there. In the warmer months, I open the single window that is in the room and that seems to help also, as does leaving the door open. I fully admit that I have not done any AB testing or room measurements yet. However, I also fully admit that I love the way it sounds. Also, car audio by necessity is conducted in much smaller spaces than my den, yet with the modern DSP built into JL Audio amplifiers, I most surely enjoy the sound in both of my vehicles. The Camaro is a convertible, so I guess when the top is open it is not such a small space. I would be most interested in learning if there has been any research regarding how to enhance car audio systems specifically for convertibles, as that seems to me to be the least challenging type of vehicle with respect to acoustics (at least when it is warm enough to drive around with the top open).

 

[thewas]

AFAIK some modern convertibles change their dsp setting when the roof is opened to compensate for the missing pressure chamber effect which increases the lower bass.

 

[AudioStudies]

AFAIK some modern convertibles change their dsp setting when the roof is opened to compensate for the missing pressure chamber effect which increases the lower bass.

Yes, I had the guy doing the tuning, give me one setting for open top, and another setting for closed top; with both optimized for the driver's seat.

 

[pozz]

The audio literature makes it clear that large rooms have significant advantages over small rooms with respect to acoustics.

Not necessarily. The acoustical definition of a small room, I would guess (I'm not sure), would be one whose largest dimension (H,L,W) is less than the wavelength of 20Hz, which is around 17 meters or 56 feet. This is bigger than what you find with some houses! So, acoustically, large rooms would be concerts halls, stadiums and other public gathering places (town halls, churches).

In large rooms the issues are with controlling coverage patterns (even FR across a large seating area; example here) and highly delayed early or late reflections that still have significant energy. It's entirely possible that a poor layout could cause a patron to hear both the direct sound and reflections as two separate events in certain seats. Modern fan-shaped concert halls are so big relative to traditional shoebox-type halls like the Concertgebouw in Amsterdam that reinforcement (either for direct sound or reverberation) has to be used to supplement the finite energy and instrument directivity of the performers. Then there are temperature gradients and air-based absorption issues.

Small rooms have a different set of problems. Creating a well-controlled acoustic space in either case is not easy.

 

[AudioStudies]

@pozz - Ballou, Glen (Editor), “Handbook for Sound Engineers” – 1st ed., 3rd printing (1988) seemed to paint a dismal picture for small rooms, but I guess that is an old source. But I am sure you are right that large rooms have problems of their own.

 

[JoachimStrobel]

Well, one thing I have learned about the sciences is that there tend to be disagreements at every level, from those with BS degrees to those with PhDs. While I fully confess that I have a lot more reading to do, I haven't seen too much disagreement with the research of Dr. Toole and if by (& Friends), you mean Sean Olive. I have now read most of Dr. Toole's book, and the reasoning, research, documentation, and even the writing style, I find to be top-notch. There have been some questions raised, though. I think someone on ASR questioned Dr. Toole's choice of using passive monitors rather than powered studio monitors, when the many advantages of the active monitors are well known. I admit, that one has me a bit baffled also, as there are many documented advantages of using powered monitors with active (rather than passive) crossovers. If I had to guess, I would think it is possible that certain passive monitors may excel in aspects related to psychoacoustics in a way that no powered monitor has yet achieved. But then again, I think that might be a bad guess (and I have made some whoppers) because this is 2020 and the SOTA of powered monitors is quite high. I just don't know. What I do know, is this post is likely to generate some responses = LOL.

By no means did I want to discredit any of Toole’s and Olive’s work. Comparing theirs to other’s work will let it shine even more. If I fish deep enough, then my only take would be, that Toole does concentrate a little too much on classical music with it’s large concert hall. I wonder if some concepts are applicable for jazz music played in small clubs vs in a living room. While a Mch recording of a symphonic orchestra will focus on the hall, such a recording from a small jazz combo might have different objectives, potentially defining a new genre of recordings with dominantly direct sound which, unless I did not read it, did not quite make into Toole’s book. A similar argument could be made for his handling of room curves which seems to concentrate on recreating concert hall behavior.

 

[j_j]

How much genuine research has been done into car audio, and where are the relevant web sites? Looking for something beyond what I can find on the sales web sites, but if there are some of the sales sites that have excellent technical info, I would want to know about those also. I have JL Audio systems in both my Jaguar & Camaro.

There's a bunch of stuff, but it's mostly proprietary.

 

[j_j]

@pozz - Ballou, Glen (Editor), “Handbook for Sound Engineers” – 1st ed., 3rd printing (1988) seemed to paint a dismal picture for small rooms, but I guess that is an old source. But I am sure you are right that large rooms have problems of their own.

Well, small rooms are problematic, unless some serious mitigation is undertaken.

 

[pfzar]

Hello. Been a lurker on here. I suggest these books.

Blauert, Spatial Hearing.
Schnupp, et al. Auditory Neuroscience Making Sense of Sound,
Suzuki, et al. Principals and Applications of Spatial Hearing.

As far as automotive. Yes loads of research, search the AES.

 

[Wes]

How much genuine research has been done into car audio, and where are the relevant web sites? Looking for something beyond what I can find on the sales web sites, but if there are some of the sales sites that have excellent technical info, I would want to know about those also. I have JL Audio systems in both my Jaguar & Camaro.

quite a bit but much is secret

one thing I have learned about the sciences is that there tend to be disagreements and they get resolved by experiments; if that cannot happen then people wander off somewhere else

 

[AudioStudies]

As far as automotive. Yes loads of research, search the AES.

I now the AES has free access to some of its documents. I looked into membership at one time, but it didn't look like I qualified.

 

[pfzar]

Anyone can join.

 

[AudioStudies]

Anyone can join.

Info I read on the web site would seem to contradict that, but perhaps I read it wrong. Maybe I should just phone them.

 

[pfzar]

You don’t need to phone them. Just join. An associate member status is what you are after. It’s not an exclusive club. If you like I can send a referral.

 

[j_j]

If you have any professional audio work, you should qualify for membership as a full member. Associates, however, do get access to the library. Back when I was a board member, I advocated for eliminating the current breed of associate member, since the AES is both a professional society AND an educational society, but the Secretary and Treasurer of that time simply fillibustered that away.

 

[pfzar]

 

[DualTriode]

Well, one thing I have learned about the sciences is that there tend to be disagreements at every level, from those with BS degrees to those with PhDs. While I fully confess that I have a lot more reading to do, I haven't seen too much disagreement with the research of Dr. Toole and if by (& Friends), you mean Sean Olive. I have now read most of Dr. Toole's book, and the reasoning, research, documentation, and even the writing style, I find to be top-notch. There have been some questions raised, though. I think someone on ASR questioned Dr. Toole's choice of using passive monitors rather than powered studio monitors, when the many advantages of the active monitors are well known. I admit, that one has me a bit baffled also, as there are many documented advantages of using powered monitors with active (rather than passive) crossovers. If I had to guess, I would think it is possible that certain passive monitors may excel in aspects related to psychoacoustics in a way that no powered monitor has yet achieved. But then again, I think that might be a bad guess (and I have made some whoppers) because this is 2020 and the SOTA of powered monitors is quite high. I just don't know. What I do know, is this post is likely to generate some responses = LOL.

Hello All,

About powered monitors; Harmon / JBL / Crown is in the business of selling speakers, amplifiers and monitors. Dr. Toole is not about to take a position favoring one over the other.

Is the M2 speakers or monitor? The equalized active crossover Crown amplifier is not built into the box.

 

[AudioStudies]

I started another thread entitled Car Audio. Feel free to jump in over there, if you are so inclined.

 

[AudioStudies]

Ballou (1) identifies that for convenience the audible spectrum can be divided into four regions:

• Region X: a very low frequency region, wherein no modal effects can occur;
• Region A: a low frequency region dominated by normal modes;
• Region B: an intermediate frequency region dominated by diffraction and diffusion;
• Region C: a higher frequency region dominated by specular reflection.

I would like to learn more about listening in small volume environments, such as that of a small den in a home, or even in volumes as small as an automobile. I think it is pretty much agreed that small rooms are acoustically problematic and require serious treatment. Consider the case of a small room that has serious treatment, lets assume state of the art treatment. In such a superbly treated room, what limitations remain? My understanding is that treatment is effective in Regions A, B, and C. My understanding is that there are no treatment options for Region X. So does a superbly treated small room still suffer disadvantages (compared to a large room) because of the inability to treat Region X? If so, what are those disadvantages?