Just finished reading this book today, and it was a relatively easy yet very interesting read. The first half of the book goes over the research performed by Dr. Toole and others on how humans perceive sound. The second half explains how to apply these findings in the design of listening rooms and home theaters.
Many of Dr. Toole's recommendations contradict the conventional wisdom. For example, he cites research that shows that test subjects prefer early reflections in music because it gives an enhanced sense of spaciousness. He recommends only treating early lateral reflection points if the main speakers have poor off-axis frequency response, or if the listener prefers the sound that way. Toole goes on to say that if absorption is used it should be at least 3-4" thick so that it can absorb effectively down to 300hz or so. He claims the problem with thinner material is that it only absorbs the upper frequencies and thus changes the spectrum of the reflected sound.
Toole also cites research showing that, in most cases, comb filtering does not adversely affect listening enjoyment.
One of the most fascinating (and entertaining) sections of the book covers the issue of listener bias due to the brand, size, price, appearance etc. of speakers. He cites tests performed under both blind and sighted conditions with the same group of subjects and speakers of various sizes, finishes and brands. Unsurprisingly, the results were very different when subjects could see what speaker they were judging.
Obviously, I'm barely scratching the surface of the book's content, and I'm sure some will disagree with a few of Toole's conclusions, but it is clear that he has really done his homework, and over the course of his career had access to tools that most professionals can only wish for. Definitely worth a read for enthusiasts and professionals alike.
Many of Dr. Toole's recommendations contradict the conventional wisdom. For example, he cites research that shows that test subjects prefer early reflections in music because it gives an enhanced sense of spaciousness. He recommends only treating early lateral reflection points if the main speakers have poor off-axis frequency response, or if the listener prefers the sound that way. Toole goes on to say that if absorption is used it should be at least 3-4" thick so that it can absorb effectively down to 300hz or so. He claims the problem with thinner material is that it only absorbs the upper frequencies and thus changes the spectrum of the reflected sound.
Toole also cites research showing that, in most cases, comb filtering does not adversely affect listening enjoyment.
One of the most fascinating (and entertaining) sections of the book covers the issue of listener bias due to the brand, size, price, appearance etc. of speakers. He cites tests performed under both blind and sighted conditions with the same group of subjects and speakers of various sizes, finishes and brands. Unsurprisingly, the results were very different when subjects could see what speaker they were judging.
Obviously, I'm barely scratching the surface of the book's content, and I'm sure some will disagree with a few of Toole's conclusions, but it is clear that he has really done his homework, and over the course of his career had access to tools that most professionals can only wish for. Definitely worth a read for enthusiasts and professionals alike.