Pages · · MB · Downloads ·English Floyd Toole, a leading expert in the field of sound reproduction, explains how to design the best. Sound Reproduction. Loudspeakers and Rooms. Floyd E. Toole. AMSTERDAM • BOSTON • HEIDELBERG • LONDON. NEW YORK • OXFORD • PARIS • SAN. Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and ByFloyd E. Toole DownloadPDF MB Read online.
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Read "Sound Reproduction The Acoustics and Psychoacoustics of Loudspeakers and Rooms" by Floyd E. Toole available from Rakuten Kobo. Sign up today. Floyd Toole. PAPERS Loudspeakers and Rooms for Sound Reproduction—A Scientific Review* FLOYD E. TOOLE ([email protected]) Harman International . 6, June TOOLE PAPERS out the space , . Download pdf. Floyd Toole, a leading expert in the field of sound reproduction, explains how to design the best possible listening experience for recording control rooms and.
Rigid fiberglass board is an excellent absorber, until the surface is closed by painting or covering with the wrong kind of fabric. Thus we arrive at the fundamental concept of flow resistance: to maximize the acoustic absorption, there is an optimum resistance to air flow.
The resistive material must also be in the right location. Since the mechanism is flow resistance, these materials will obviously be most effective when located where molecular motion is at a maximum. The Figures in Section 2. Suppose we wanted to try to damp an overly energetic axial mode using a resistive absorber. Using the example shown in Figure 8, where would you place a 2-inch thick fiberglass panel to be most effective? Attaching it to the wall would be useless, because the particle velocity - i.
Nothing is moving much so nothing much happens. Moving it away from the wall improves things, until we get to the middle of the room, and some serious damping occurs. At low frequencies it is simply not practical to use resistive absorbers. As wavelengths get shorter, the regions of maximum particle velocity get sufficiently close to the reflecting surfaces that materials of practical thickness, or drapes hung at normal distances, will work.
Thus we come to a rule that resistive absorbers are the devices of choice for absorbing mid- and high-frequency sounds. The proof that they are absorbers is that they vibrate in response to bass sounds; acoustical energy is converted into mechanical energy.
As luck would have it, conventional home construction, gypsum board on 2 x 4 studs, is an effective low-frequency absorber - play some loud music and feel the walls.
Doubleglazed windows are quite similar in their absorption properties, so we are off to a good start. The worst possible rooms are those built in basements, with concrete floor and walls.
Such rooms need to have false walls built inside them. Concrete floors are a problem for two reasons. First, they dont absorb sound. Second, because they dont absorb sound, they dont vibrate and supply the tactile sensation of bass through the soles of the feet.
In these cases, a false floor is a useful addition. Oh yes, leather upholstered furniture is also a membrane absorber, and also provides vibratory sensations to stimulate the audience.
Obviously, it is possible to construct customized absorbers to address problems at specific frequencies. Reference 16 has design aids for diaphragmatic absorbers p. Remember to place them at high-pressure points for the mode that is being damped. No advanced coding skills are necessary. The freeDSP works with a free graphical development environment.
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The programming model is function-block based. Just drag-and-drop some processing blocks and virtual cables - and you are ready to go! The outcome would be a design that is available to anyone free of charge, or based on donations.
There would be no proprietary component in this. Rather than competing with each other, in order to get the ego satisfaction of coming up with the worlds best design, I would like to work as a group working together for a common goal, deriving not ego satisfaction, but something possibly much more satisfying in the end, the knowledge of having contributed to the common good. The new "inverse coding" methodology will be highlighted.
I think compression is the primary problem and not lossy coding, if the data rate is greater than kbps. They also point to glossy headphones, earbuds and portable devices as contributors to the sad state of sound reproduction.
I suspect that the master tapes are already compressed and distorted for minimum dynamic range and maximum continuous loudness. The page book is well organized, clearly written and illustrated with easy to understand graphics. A timely, interesting, mostly to the point, but not conclusive article about the state of the loudspeaker industry. To express my sentiments and to start the discussion in the Journal I responded with: It is about time that the audio industry and academia address the loudspeaker and room compatibility issue for domestic size reverberant spaces and recognize it as just one more problem area in the transmission path from microphone membrane to eardrum.
The brain takes over behind the ear drums, creating the perception of an acoustic event in some form of 3D space.
Sound Reproduction Loudspeakers and Rooms - Floyd E. Toole
The perceived scene is spatially distorted due to the directional characteristics of microphones and their distances to sound sources, and due to the directional characteristics of loudspeakers and their distance and azimuth to the listener. The microphone output signals contain a limited and specific view of the original acoustic scene.
On playback the loudspeakers illuminate the listening room. The resulting eardrum signals consist of superimposed streams of air pressure variations arriving from different directions. With two ears, a movable head, a brain and a mind, evolution has formed a superbly capable perceptual apparatus, which automatically sorts a plurality of sound streams for direction, distance, meaning and for focusing attention.
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Loudspeakers and room also the room behind the speaker membrane must not provide misleading cues to a listener's brain in order to fully hear the information contained in the microphone signal streams and to instinctively withdraw attention from loudspeakers and listening room.
The result is a convincing auditory illusion. The job can be done. It has been done. A simple stereo system can render in an ordinary room a more convincing 3D illusion than conventional multi-channel surround setups, because it can put perception at ease.
Why has the audio industry not caught on other than trying to put patches on the problem for decades? Acoustical and visual quality of the transmissions is excellent and fully matches the musical performances.
If you love symphonic music or want an introduction to it, I cannot think of a better avenue. Concerts sound wonderful over the LX or the LXmini.
The system consists of 6 x 1m high Radia Pro 1. In addition to this are two dipole satellite bass cabinets, one under the main floor and one under the balcony seating to augment bass at these locations the columns are effectively a line source whereas the bass falls as per a spherical source. The bass cabinets are directly under the stage below the column array.
The satellite bass cabinets have been delayed so that even though you can feel yes feel their effect you still locate the stereo image frontally to the stage 55msec delay to the stall underseat, bass and 95 msec delay to the balcony underseat bass.
A test concert was held last Sunday and while there is room for improvement the system is performing well. Two things were notable: Very even response with minimal changes between positions in the audience areas, stalls and balcony you can also stand very close to the system without it being excessively loud.
The null of the system points diagonally across the stage. Stage located source and image - one of the goals of the design was to have an soundstage at or near the actual stage. Locating the system on the stage and having very consistent horizontal directivity allows the early reflections to be similar to the stage acoustic sources and this also is important for making the system less obvious.
To test the transparency of the system during the orchestra performance I fed a bridge pickup from a double bass into it and panned it to approximately the same location as the double bass was on stage - no one I asked was aware that there was any involvement of the sound system in the performance.
This was exactly my intention, subtle reinforcement of acoustic performances if they need some help. One aspect that was 'discovered' when I was eq'ing the columns was that they do not revert to dipole behaviour as readily as I was expecting - you are still effectively very nearfield even a couple of metres back - this made the determination of the dipole correction less straightforward than I was expecting as once further into the Hall the room reflections then started to cloud the measurements.
Also interesting was the difference in spatial quality between tapering the columns in level and not for the taper I used, from the bottom column, -6dB, The tapering notably improved the sense of space in recordings or it may be that the image is just unnaturally big without the tapering.
Its a little bit difficult to photograph the array and it is also fairly innocuous, something I wanted. The photo shows how in-situ the array is tilted back to approximately match the audience slope with a toe-in of 24 degrees so that each column covers the entire seating area. This also directs the null towards the middle of the stage. The holes in the 'baffle' were used to shift the first dipole response notch to as high a frequency as possible and also to blur the distance to this edge.
Lots of fun and it does sound pretty respectable! Played some Bucky Pizzarelli in your honour. Toole explains in detail how the loudspeakers can behave in the acoustic situations of both normal and treated rooms, and how human hearing perception responds to room acoustics.
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Humans can hear the rooms, and we can also hear through the rooms, that is to say, we can quickly adapt to room acoustics and hear the sound signature of the source of acoustic emission beyond the room acoustics. A room will shape the sound of the loudspeaker in it, but we can still hear how well the loudspeaker is performing after our hearing has acclimated to the acoustics, which usually occurs very quickly.
However, some acoustic environments will take a greater toll on the emitted sound than others, and Dr. Toole elucidates some of the actions that can be done to cope with suboptimal room conditions.
What is the point of achieving a near-perfect audio system when the content that it reproduces can vary so wildly due to the fact that there was no consistent reference point by which they were reproduced? One startling fact that Dr.
Toole discusses is how badly flawed many of the monitoring systems are that were used in recording and mastering studios. If the audio systems that were used to mix and master the recordings had a poor frequency response, the sound engineers will be creating a sound mix that sounds good on that particular system, but when that sound mix is reproduced on a system that is far more accurate and linear, it can sound odd, since it was created with inherent compensations for an acceptable sound on a problematic sound system to begin with.
Hearing loss will most commonly occur as a reduction in high-frequency sensitivity, so sound engineers can end up boosting high-frequencies to compensate for their hearing, and that can leave the sound mix to be blazing hot in treble for those of us with good hearing. This brings me to another point that Dr. OSHA noise exposure criteria actually allows for a substantial amount of hearing damage to occur. Just when I think I am becoming too cynical, I find out I am not cynical enough!
Something else that Dr. Toole explains that might be a bit provocative is the ineffectiveness of automated room correction equalization such as Audyssey outside of bass frequencies.
He makes a very good case to this effect, and I am forced to agree with him. Automated room correction routines are more of a band-aid for flawed loudspeakers rather than an improvement for typical room acoustics.
Automated room correction can actually make things worse by attempting to correct for diffraction and acoustical interference effects which change with distance and angle, so in adjusting the frequency response for one position it can mess up the response for many other positions.
Its true usefulness is mostly only in bass frequencies, and even then it can only really help a single listening position unless multi-sub solutions have been involved to reduce seat-to-seat variations.
Toole covers at length is the shortcomings of stereo sound compared to multi-channel formats. Stereo sound recordings can sound great, as so many of us know, but has some severe disadvantages versus 5.
In a typical surround sound mix, in addition to a soundstage with a stable center image regardless of listening position that the center speaker provides, the surround speakers can create a greater sense of a different acoustic environment than the room that they are situated in.
The psychoacoustic research that Dr.It performed exceedingly well in giving the venue different acoustics, appropriate to the style of music being played by the musicians or sounds being rendered. The result is a convincing auditory illusion.
It was an exciting event. A review of the scientific literature on loudspeaker listening tests indicates that recordings are a serious nuisance variable that need to be carefully selected and controlled in the experimental design and analysis of test results. Something else that Dr. A free copy of this paper can be downloaded here  Sean E. This also directs the null towards the middle of the stage.
The relationships make sense. My active crossover, multi-channel loudspeakers put much less demand on the individual amplifiers, than the typical n-way passive crossover speakers that are common place, because each amplifier sees a benign load made up of the speaker cable, the voice coil impedance and the motional back emf.