Audio � Science in the Service of Art

[Colin]

Dont know where the thread went, but somebody posted a link to an interesting harmon/kardon white paper article. Thanks. This 29 page PDF paper reads easy enough, but even with broadband it is huge and comes up slowly. In short, here are some of the interesting things it says:

E. Toole, Ph.D., Vice President Acoustical Engineering, Harman International Industries, Inc. http://www.harman.com/wp/pdf/AudioScience.pdf

all of the tests were conducted blind. Other physical and

psychological factors known to be sources of bias were also well

controlled . The results were very clear. When the data

were compiled, it turned out that most people, most of the time,

liked and disliked the same loudspeakers.

All of these erratic listeners had hearing loss.

Early reected sounds have been reected only once in transit and, in most domestic-size rooms, will arrive within approximately the first twenty to thirty milliseconds (ms) after the direct sound.

Wide dispersion or multidirectional loudspeakers generate lots of early reflections, meaning that, for such speakers the acoustics of the room are major determinants in how they sound.

All-round good on-axis behavior makes a loudspeaker very room friendly, with

a high probability of sounding good in a wide variety of rooms.

Price is certainly an unreliable indicator of sonic excellence.

Our ears are very highly attuned to the detection and evaluation of resonances, and it

is therefore no surprise that listeners zero in on them as unwanted editorializing

when they appear in loudspeakers.

many commonly-used and published measurements simply cannot reveal visual evidence

of certain kinds of audible problems falling within a critical portion of the frequency

range that of the human voice and below.

An interesting fact now emerges: that the conventional method of specifying frequency response, ± x dB, is useless unless the tolerance is very, very small. High-Q phenomena could

be ± 5 dB, while moderate-Q resonances could be ± 3 dB and low-Q and other broadband deviations could be ± 0.5 dB, and all of them would be equally audible!

It is easy to understand how the popular belief that you cant measure what

you can hear came to be. Bad measurements and useless specifications are responsible.

Among the results are conclusions that the flatness and smoothness of high-resolution on-axis curves need to be given substantial weighting.

Audio Science in the Service of Art 20

The winners are easy to pick; flat and smooth are beautiful.

It is probably correct to say that the majority of listeners find stereo to

be pleasantly embellished if the room reflections are energetic. The sound tends to be open

and spacious, with a good sense of depth, but specific images might be rather vague in

other words, rather like real concerts. However, some listeners prefer a very specific, almost pinpoint, sense of image position. These people are attracted to highly directional horn and large panel loudspeakers.

In the investigation of many rooms over the years, I would estimate that something like 80% have serious bass coloration - too much, too little, boomy, uneven, etc.

There are two steps in the solution. The first step is to decide how many listeners should

have expectations of good bass. Seat-to-seat variations in bass quality can be huge. If there

is only a single listener, then proceed immediately to EQUALIZATION. If there are multiple

listeners deserving of good bass, then visit SOUND FIELD MANAGEMENT for explanations

of how to employ multiple subwoofers to achieve more uniform bass at several seats

in a room.

It turns out that there are, in fact, two solutions : one for

simple rectangular rooms, and one for rooms with more complicated shapes.

With one subwoofer, and a lot of luck, it is possible to deliver good bass to a single

listener. But what if you are not lucky? With one subwoofer, a device capable of measuring

high-resolution (1/10-octave or better) frequency responses, and a parametric equalizer, it

is possible to deliver good bass to a single listener no luck required.

[jdm56]

Thanks Colin, that was very interesting.

[DrWho]

I'm curious as to where bose falls into all of this considering they don't think a flat frequency response means anything. I'm just thinking bose would make a great example of something totally deviating from the trends found in the discussion. I know Bose isn't great by any means, but they aren't that bad either (ignoring price).

[BLSamuel]

Colin - the link is natually broken. Any chance you could attach the PDF file?

Thanks,

Ben

[Marvel]

It could be this one...

http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/AudioScience.pdf

but he did this one too...

http://www.harmanaudio.com/all_about_audio/audio_art_science.pdf

[Daddy Dee]

thanks Colin. interesting.