It contains many references to work done by researchers all over the world, but among them are references to work done by my research colleagues and me over the years. Consequently, in this introduction to the new edition, I will also introduce myself, my motivations, and my approach to examining aspects of audio. The first edition of the book was clearly oriented to explaining the science underlying the acoustics and psychoacoustics of loudspeakers, rooms and the listeners who derive pleasure from the combinations. What was called the second edition was a labeling error associated with a change in publishers. The book was unchanged.
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Ferstler Volume 31 No. A major researcher in audio systems and design, particularly in the realm of small-room acoustics and the relationship between measurements and listener perceptions, Toole studied electrical engineering at the University of New Brunswick, receiving a BSc in Upon graduation, he joined the Acoustics and Signal Processing Group of the National Research Council NRC; Ottawa, Canada , where he expanded his interests into the complicated interactions of room acoustics and loudspeakers, particularly as they related to the psychoacoustic relationship between what listeners hear and the technical measurements that are used in the design and evaluation of audio products.
The research resulted in improved methods for subjective evaluations and technical measurements. Later work focused on one of the fundamental problems in audio, the perception and measurement of resonances, for which with Sean Olive he received the AES Publications Award. He retired from Harman in and has since devoted his spare time to consulting. In he received the AES Silver Medal Award, presented in recognition of outstanding developments in the subjective and objective evaluation of audio devices.
The book is divided into two parts, with numerous smaller topic sections, and still more subject breakdowns within those sections. Sound Reproduction 3. Sound Fields in Rooms 5. The many effects of reflections 6. Reflections, images and the precedence effect 7.
Impressions of space 8. Imaging and spatial effects in sound reproduction 9. Reflections and speech intelligibility Adaptation Adjacent-boundary and loudspeaker mounting effects Multichannel options for music and movies Loudspeakers I: subjective evaluations Loudspeakers II: objective evaluations Closing the loop: predicting listener preferences from measurements Acoustical materials and devices Designing listening experiences: recommendations There are a multitude of charts and drawings, including numerous frequency-response graphs and room-layout diagrams.
Toole dwells on some topics at length, and often refers back to them. He is obviously trying to get serious points across, and does so with enthusiasm. Of course, other rational writers and research-oriented manufacturers have been saying the same things about these basic ideas and conclusions for many years, although not on so comprehensive a scale, nor with this kind of documentation.
For example, he lauds the idea that a speaker needs to not only be smooth on axis but also needs to be smooth off axis. Of course, codecs, phase behavior, plus things like amp distortion, tubes vs solid state, and speaker wire issues remain debated within the audio-tweak community. Toole does everybody a service with his analysis of those issues. He even does a very fine job of debunking the myths surrounding the so-called dipolar surround speaker design mandated in the THX home theater specifications.
While it might be esoteric hair-splitting on my part, I do want to mention some of those omissions. He also might have been amazed at what the speaker could do in relation to the need for very wide and smooth broad-bandwidth dispersion.
This means that reflections from adjacent room boundaries when employing them as front-channel systems are not only smooth which Toole prefers , but also fairly powerful which he seems to not come to grips with. Interestingly, on page Toole mentions that listeners appear to prefer the sound from wide-dispersion loudspeakers not wide by Allison standards, but wide by more mainstream ones with somewhat colored off-axis behavior, to the sound from narrow-dispersion models with less colored off-axis behavior.
There is virtually no analysis concerning, and no reference to any research into, what a front-channel system having this kind of ultra-wide dispersion characteristic with minimal off-axis coloration could deliver to the listener. He also mentions page that the AR-3 was considered dull by some listeners.
The later AR-3a was judged by many critics to sound brighter. Given the almost cult status of that speaker, I find the lapse odd.
At one place in the book he might have the AR-3 and the AR-3a mixed up. On page he states " The Acoustic Research AR-3 figure Its acoustic performance was well documented in the literature e.
Both speakers were references of a sort during their production runs, but the AR-3a was a better speaker. Also, on page 14 he mentions the live-vs-recorded sessions Edgar Villchur produced with the AR-3, but Toole seems to ignore their importance. All he has to say about what transpired is that numerous later design speakers from a variety of companies are better. Another very highly regarded speaker of the era was the AR-LST, which has achieved almost iconic status.
Both the Allison Model One and the AR-LST were designed by Roy Allison, and both used multiple drivers on angled panels for much wider dispersion than available from systems having a single, forward-facing panel. Yet virtually none of the front-channel speakers Toole dealt with in the book appear to have made use of multiple drivers on angled panels. If ultra-wide dispersing speakers are not best for L-, C-, and R-channel use, the book should have discussed their designs and explained why they are not viable.
Regarding that approach to sound radiation, it is notable that Toole makes no mention of Bose or their systems. That design certainly has its detractors and enthusiasts , but it did make a splash Julian Hirsch went on at length about the design in his review.
That speaker is a nightmare or legend, depending on your perspective , and should have been analyzed, especially in a book that deals so emphatically with room reflections, cross correlation, envelopment, etc. Another speaker that made a big splash was the original two-way Large Advent, but I found no comments about it.
Perhaps it was discussed and measured, but only listed as "speaker A" or "speaker Y. Another missing link was the Klipschorn, which certainly is an iconic item that some buffs would kill to own. While not a big seller in recent years, the speaker is an interesting enough design to warrant at least a comment or two, regardless of the conclusion.
Mark Davis and John Strohbeen obviously went well beyond what Roy Allison pursued in the realm of super-wide dispersion. Speakers like these and the Allison models as well as the AR-LST and AR-3a certainly ought to have rated at least a footnote-grade comment here and there. Many other brands and approaches were also ignored, such as Dunlavy, Waveform and Carver, each of which stands in sharp contrast to much of the competition, including those that were discussed at length.
These companies have at times carried a lot of weight in the business, and it would have been instructive to see just what their assorted models could do.
Of course, if Toole wrote about all of the abovementioned models in addition to those it did cover, the book would probably be pages long. In addition, just acquiring the various models and doing the work when Toole was at the NRC and later Harman would have been prohibitively time consuming, tedious, and expensive.
In any event, I find it troubling that so many innovative designs were ignored, both in his book and in a number of his JAES articles, particularly when many of them were lionized by the audio public and their designers were considered among the best. It is possible that some of these speakers were analyzed by Toole when he was with the Canadian NRC and later at Harman, but we are dealing with the book, and they were not included.
Omissions aside, the book offers much that is very helpful. For example, it delivers a fine analysis of subwoofer behavior in small rooms and I agree completely with Toole when it comes to smoothing the overall response by sensible placement and the use of more than one.
I am pretty sure that most home-theater enthusiasts do not have that many seats. Thus, the need for multiple subwoofers might not be all that great for most of them. Two are not a bad idea, in any case. There is one other area where Toole and I part company: his approach to response measurements and equalization. Going to the extreme he outlines might demoralize some enthusiasts and turn them off to the hobby.
If they have a decent room and decent speakers, that might be more than enough. Limitations notwithstanding, I told my readers that a room curve of this kind was only a starting point.
Perhaps Toole has done all this. From my own experience I would strongly suggest that spatial and temporal averaging are key to equalization. It is posted on Enjoy the Music.
Sound Reproduction: Psychoacoustics of Loudspeakers and Rooms
Ferstler Volume 31 No. A major researcher in audio systems and design, particularly in the realm of small-room acoustics and the relationship between measurements and listener perceptions, Toole studied electrical engineering at the University of New Brunswick, receiving a BSc in Upon graduation, he joined the Acoustics and Signal Processing Group of the National Research Council NRC; Ottawa, Canada , where he expanded his interests into the complicated interactions of room acoustics and loudspeakers, particularly as they related to the psychoacoustic relationship between what listeners hear and the technical measurements that are used in the design and evaluation of audio products. The research resulted in improved methods for subjective evaluations and technical measurements. Later work focused on one of the fundamental problems in audio, the perception and measurement of resonances, for which with Sean Olive he received the AES Publications Award.
Dr. Floyd Toole' system - with pictures