Steve,
here's my take.
It has been said in the thread, that knowledge of the acoustics of large spaces does not necessarily mean that those guys are capable of doing a good job in small rooms. It’s not a mere matter of downsizing/downscaling, this becomes very clear when you look at perceptual thresholds of e.g. early reflections. Small rooms as such have very different issues, and the fact that music is reproduced by (more or less directional) loudspeakers adds an extra layer of complexity, just think of adjacent boundary effects.
What I would expect from an acoustician is that he is familiar with the technical literature relating to small rooms and related psychoacoustics, Floyd Toole’s book and the references cited therein would be the strict minimum. Are acousticians aware of the fact that human hearing has its very particular manner of processing sound, which is very different from a measurement microphone? Does the acoustician take equal loudness contours into account when measuring room mode amplitudes, does he know about binaural decoloration when addressing the issue of early reflections? Does he know about the interaction loudspeaker – listening room? The speakers’ off-axis behaviour has been mentioned: does he ask to see measurements? Did he ask for measurements in your case, Steve?
However, having read large parts of Toole’s book and many of those references I would say that in most cases an acoustician is not needed simply because there are no problems that need to be solved. As an example a quote from Toole: “the widespread belief that these reflections should be eliminated as a matter of ritual.” It is quite simple, for most, if not all of the rituals in small room acoustics there is no supportive evidence. It is done, without having investigated if the problem actually exists perceptibly.
It has also been said that “there is not an information enough about small room acoustics that allows someone to make an educated choice”. I beg to differ: there is plenty of information, Toole’s book for instance, and research is more and more focussing on the perceptual aspect of things, as becomes evident from the AES. Since it’s humans who listen to music in those small rooms, you must consider the perceptual side of the issue, you cannot rely on measuring alone.
As is known from psychoacoustic literature, in-ear frequency response may vary considerably from one person to another:
Shaw, "Earcanal pressure generated by a free sound field", J. of Acoust. Soc. of America 1965, vol. 39, no.3, p.465
Which simply means that what another person hears might be irrelevant for you:
Philip Newell, "Recording Studio Design", Focal Press 2008
"In my first book I related a story about being called to a studio by its owner, to explain why hi-hats tended to travel in an arc when panned between the loudspeakers; seeming to come from a point somewhere above the control room window when centrally panned. The owner had just begun to use a rather reflection-free control room, in which the recording were rendered somewhat bare. On visiting the studio, all that I heard was a left-to-right, horizontal pan. We simply had different pinnae."
and
"Studio Monitoring Design (Ph. Newell 1995) also related the true story of two well-respected recording engineers who could not agree on the 'correct' amount of high frequencies from a monitor loudspeaker system which gave the most accurate reproduction when compared to a live cello. They disagreed by a full 3 dB at 6 kHz, but this disagreement was clearly not related to their own absolute high frequency sensitivities because they were comparing the sound of the monitor to a live source. The only apparent explanation to this is that because the live instrument and the loudspeakers produce different sound fields, the perception of the sound field was different for each listener. Clearly, all the high frequencies from the loudspeaker came from the very small source, the tweeter, whilst the high frequency distribution from the instrument was from many points - the strings and various parts of the body. The highs from the cello radiated, therefore, from a distributed source having a much greater area than the tweeter. So, given the previous discussion about pinnae transformation and the different HRTFs as they relate to sound arriving from different directions, it does not seem too surprising that sound sources with spatially different origins may result in spectrally different perceptions for different people."
Klaus
here's my take.
Steve Williams said:
It has been said in the thread, that knowledge of the acoustics of large spaces does not necessarily mean that those guys are capable of doing a good job in small rooms. It’s not a mere matter of downsizing/downscaling, this becomes very clear when you look at perceptual thresholds of e.g. early reflections. Small rooms as such have very different issues, and the fact that music is reproduced by (more or less directional) loudspeakers adds an extra layer of complexity, just think of adjacent boundary effects.
What I would expect from an acoustician is that he is familiar with the technical literature relating to small rooms and related psychoacoustics, Floyd Toole’s book and the references cited therein would be the strict minimum. Are acousticians aware of the fact that human hearing has its very particular manner of processing sound, which is very different from a measurement microphone? Does the acoustician take equal loudness contours into account when measuring room mode amplitudes, does he know about binaural decoloration when addressing the issue of early reflections? Does he know about the interaction loudspeaker – listening room? The speakers’ off-axis behaviour has been mentioned: does he ask to see measurements? Did he ask for measurements in your case, Steve?
However, having read large parts of Toole’s book and many of those references I would say that in most cases an acoustician is not needed simply because there are no problems that need to be solved. As an example a quote from Toole: “the widespread belief that these reflections should be eliminated as a matter of ritual.” It is quite simple, for most, if not all of the rituals in small room acoustics there is no supportive evidence. It is done, without having investigated if the problem actually exists perceptibly.
It has also been said that “there is not an information enough about small room acoustics that allows someone to make an educated choice”. I beg to differ: there is plenty of information, Toole’s book for instance, and research is more and more focussing on the perceptual aspect of things, as becomes evident from the AES. Since it’s humans who listen to music in those small rooms, you must consider the perceptual side of the issue, you cannot rely on measuring alone.
As is known from psychoacoustic literature, in-ear frequency response may vary considerably from one person to another:
Shaw, "Earcanal pressure generated by a free sound field", J. of Acoust. Soc. of America 1965, vol. 39, no.3, p.465
Which simply means that what another person hears might be irrelevant for you:
Philip Newell, "Recording Studio Design", Focal Press 2008
"In my first book I related a story about being called to a studio by its owner, to explain why hi-hats tended to travel in an arc when panned between the loudspeakers; seeming to come from a point somewhere above the control room window when centrally panned. The owner had just begun to use a rather reflection-free control room, in which the recording were rendered somewhat bare. On visiting the studio, all that I heard was a left-to-right, horizontal pan. We simply had different pinnae."
and
"Studio Monitoring Design (Ph. Newell 1995) also related the true story of two well-respected recording engineers who could not agree on the 'correct' amount of high frequencies from a monitor loudspeaker system which gave the most accurate reproduction when compared to a live cello. They disagreed by a full 3 dB at 6 kHz, but this disagreement was clearly not related to their own absolute high frequency sensitivities because they were comparing the sound of the monitor to a live source. The only apparent explanation to this is that because the live instrument and the loudspeakers produce different sound fields, the perception of the sound field was different for each listener. Clearly, all the high frequencies from the loudspeaker came from the very small source, the tweeter, whilst the high frequency distribution from the instrument was from many points - the strings and various parts of the body. The highs from the cello radiated, therefore, from a distributed source having a much greater area than the tweeter. So, given the previous discussion about pinnae transformation and the different HRTFs as they relate to sound arriving from different directions, it does not seem too surprising that sound sources with spatially different origins may result in spectrally different perceptions for different people."
Klaus
