The Advantages of Floor Coupled Up-Firing Speakers

[Don Hills]

VLC unity gain setting is 100%. Easily tested - generate a minute or so of 300 Hz 0dBfs (full amplitude) sine wave in Audacity or similar. Save as WAV and play with VLC. Adjusting gain above 100% will result in clearly audible clipping.

[markus76]

Absolutely!

[el`Ol]

I have read the first 8 chapters (140 pages) of Toole's book and I will post some quotes here, mainly for graaf, who doesn't want to buy it.

First some of Toole's thoughts about concert halls:

"...towards the rear of a concert hall, the direct sound is not the primary acoustic event. It may even be inaudible, masked by later acoustical events. Two ears and a brain comprise a powerful acoustical analysis tool, able to extract enormous resulution, detail, and pleasure from circumstances that, when subject to mere technical measurements, seem to be disastrous, Something that in technical terms appears to be impossibly scrambled is perceived as a splendid musical performance."

Forsyth (1985):
"When an orchestra plays at forte level in a compatible-sized room, strong sound reflections can be heard from the side walls and to some extent the ceiling as the music "fills the hall". This criterion of "spacial impression" has been identified as significantly important to the enjoyment of a live concert, and this is reduced when the orchestra is unable to achieve a full-bodied forte, as the early sound reflections seem to be confined to the stage area instead of coming from all directions."

"Many modern halls have become wider, expanding into a fan shape to acommodate more people while retaining good sight lines. Famous acoustician Leo Beranek (1962) notes that "listening to music there is rather like listening to a very fine FM-stereophonic reproduction system in a carpeted living room." ... Michael Forsyth (1985) comments on the tendency, especially in North America, to build "hi-fi concert halls", providing some of the impression of "front row" close to microphone recordings favored in the region. ... their tastes have been cultivated by stereo recordigs that are incapable of reproducing the full-scale envelopment of a great symphony hall. ...[trend going backwards according to a new study]... They link these trends to advances in room acoustical technologies, and the result is a more spacious, enveloping, listening experience - less like stereo."

"In live performances, it is the auditory illusion of a sound source that is wider than the visible sources; this is considered to be a strongly positive attribute of a concert hall. Perhaps becouse they lack other pleasures of live performances, many audiophiles have come to think that pinpoint localizations are a measure of excellence,..."

"a sense of being in a large space, of being surrounded by a diffuse array of sounds not associated with any localizable sound images. This is regarded as perhaps the more important component of spaciousness, differentiating good concert halls from poor ones."

"When I had the good fortune to attend rehearsals and performances of a symphony orchestra in Vienna's Musikverein, one of the most celebrated halls in the world, I was frankly not ready for the intensity of the spacial impression - the hall was indeed "full" and the envelopment was profound. It was greatly pleasurable, but for a person habituated to more modern, larger, halls and after many years of exposure to two-channel sound, the first impression was one of a surprise. It occured to me that I and my audiophile acquaintances would probably consider such an illusion to be artificially overdone if we were to hear it through a multichannel audio system."

[markus76]

Now you know what Toole's favorite music genre is and why he advocates lateral reflections for 2 channel sound reproduction. Roughly 99% of all other musical genres are NOT played in concert halls. 380 pages to go

[gedlee]

Originally Posted by markus76

Now you know what Toole's favorite music genre is and why he advocates lateral reflections for 2 channel sound reproduction. Roughly 99% of all other musical genres are NOT played in concert halls. 380 pages to go

Markus - completely correct.

Forsyth (1985):
"When an orchestra plays at forte level in a compatible-sized room, strong sound reflections can be heard from the side walls and to some extent the ceiling as the music "fills the hall". This criterion of "spacial impression" has been identified as significantly important to the enjoyment of a live concert, and this is reduced when the orchestra is unable to achieve a full-bodied forte, as the early sound reflections seem to be confined to the stage area instead of coming from all directions."

A cursious comment since it cannot possibly be true physically, such a comment would reflect a nonlinear situation. The ratio of the direct to reflecting signal is independent of the SPL level. Perhaps what is meant is that there is greater temporal masking at low levels than at high levels which allows the direct field to surpress the reflections at lower signal levels. There is some evidence for this, some of which is my own, but as an established fact, it most certainly is not. And in 1985 this comment would have been completely without any evidential support. (Not that that is anything new in audio.)

[el`Ol]

Parts of Toole's explanation of the precedence effect:

“Within the precedence effect fusion interval, there is no masking – all of the reflected (delayed) sounds are audible, making their contributions to timbre and loudness, but the early reflections are not heard as spatially separate events. They are perceived as coming from the direction of the first sound; this, and only this, is the essence of the “fusion”. The widely held belief that there is a “Haas fusion zone,” approximately the first 20 ms after the direct sound, within which everything gets innocently combined, is simply untrue.”

“It is important to notice that these very strongly worded categorical statements all emphasize that there is an accumulation of information from the various members of the sequence. It is quite incorrect to assume that the precedence effect is some sort of masking phenomenon which, by blocking out the later arrivals of the signal, prevents the auditory system from being confused. Quite to the contrary, those arrivals that come in within a reasonable time after the first one actively contribute to our knowledge of the source.”

[LineArray]

Originally Posted by el`Ol

"...
Quite to the contrary, those arrivals that come in within a reasonable time after the first one actively contribute to our knowledge of the source.”

Which is the loudspeaker in a living room environment ?

[markus76]

Originally Posted by el`Ol

precedence effect

What is "Spaciousness"?

Best, Markus

[el`Ol]

Evaluations of listener preferences, taken from Toole's book:

“Listeners appeared to prefer the sound from wide-dispersion loudspeakers with somewhat colored off-axis behaviour to the sound from a narrow-dispersion loudspeaker with less colored off-axis behavior. In the years since then, it has been shown that improving the smoothness of the off-axis radiated sound pushes the subjective ratings even further up, so it is something not to be neglected. Perhaps related to this is the acoustical crosstalk associated with the phantom center image. This coloration cannot be ignored in a situation where the direct sound is strong. Early reflections from different directions tend to fill the interference dip, making the spectrum more pleasantly neutral.”

“Using only professional sound engineers as listeners, they found that narrow-dispersion loudspeakers were required for good reproduction of voices in radio dramas; dance and popular music was also desirably “aggressive” with “highly directed” loudspeakers. The majority of the same listeners, however, preferred wide-dispersion loudspeakers for the reproduction of symphonic music at home. In the control room, though, only about half of them felt that they could produce recordings with such loudspeakers.”

“Moulton et al. (1986) performed informal listening evaluations of forward-firing designs compared to a horizontally omnidirectional loudspeaker. It was concluded that with “the stereophonic omnidirectional playback system, the musical essence of the sound seems more palpable, more enduring, and more directly accessible than we have experienced with other loudspeaker systems.”… More recently, after more investigation, Moulton (1995) stated, “It appears that broad horizontal dispersion, with the engagement of a specularly responsive set of side walls, yields preferred sonic quality for the stereophonic playback of music, both in terms of spectral accuracy and also in terms of stereophonic illusion, image and entertainment quality.””

“[Flindell et.al. (1991)] Ten of the listeners were experienced audio industry persons, and ten were naïve. In general, the naïve listeners preferred the widest possible high-frequency dispersion; the experienced listeners liked it, too, but also about equally liked a configuration that simulates a dominant direct sound above 500 Hz. Perhaps the listening circumstances allowed professionals to shift between listening modes – recreational and working… The natural concern that wide dispersion and the attendant strong early reflections “would lead to degraded stereo imaging was not confirmed by the experienced listeners using rating scales and blind presentations of audio material.” Providing a contrasting point of view, Newell and Holland (1997) present a reasoned discussion of the requirements for control-room acoustical treatment (and, by inference, loudspeaker directivity). They favor the elimination of all lateral and vertical reflections – a near anechoic space, placing listeners in a direct-sound field. They conclude that “spaceousness and the resolution of fine details are largely mutually exclusive. Spaceousness should… be an aspect of the final reproduction environment.” There is no doubt that, listening to direct sound only, recording engineers may recognize the callously stark special presentation of hard-panned left and right stereo images and be motivated to remedy it, unless this turns out to be another preference associated with the professional side of the industry. Not to be ignored in any situation in which reflected sounds have been removed is the fact that the acoustical crosstalk that plagues stereo phantom images is present in its naked ugliness, without any compensation from reflected sounds. One hopes that recording engineers in these situations do not attempt to remedy it with equalization. If they do, their compensation would be excessive for normally reflective rooms and totally wrong if ever the program is replayed through an upmix algorithm and the center image emerges from a center loudspeaker.”

“Why do recording and mixing engineers prefer to listen with reduced lateral reflections? Perhaps they need to hear things that recreational listeners don’t. This is a popular explanation, and it sounds reasonable, but experiments reported in Section 6.2 indicate that we humans have a remarkable ability to hear what is in a recording in spite of room reflections – lots of them. But there is an alternative explanation, based on the observation that some listeners can become sensitized to these sounds an hear them in an exaggerated form. Ando et.al. (2000) found that musicians judge reflections to be about seven times greater than ordinary listeners, meaning that they derive a satisfying amount of spaceousness from reflections at a much lower sound level than ordinary folk: “Musicians prefer weaker amplitudes than listeners do.” It is logical to think that this might apply to recording professionals as well, perhaps even more so, because they create artificial reflections electronically and manipulate them at will while listening to the effects. There can be no better opportunity for training and/or adaption. In fact, it is entirely reasonable to think that acousticians who spend much of their lives moving around in rooms while listening to revealing test signals can become sensitized to aspects of sound fields that ordinary listeners blithely ignore. This is a caution to all of us who work in the field of audio and acoustics. Our preferences may reflect accumulated biases and therefore may not be the same as those of our customers.”

[Key]

Originally Posted by markus76

What is "Spaciousness"?

Best, Markus

I still contend "Haas Effect" just sounds cooler.