ld wrote:Even in the implausible event that control/listening rooms were devised without regard to acoustic/psychoacoustic design principles and practice for some perverse reason, they remain the environment in which the reference sound exists. So understanding and learning from the methods employed there seems the way to fly if it is the intention to reproduce the reference sound domestically. That is my simple point.
Control room designs are based on perception threshold experiments of the type single loudspeaker/single reflection. Since it is proved fact that more than a single reflection results in less coloration I have serious doubts that the observations made using the above setups can be extended to the 2 loudspeaker/multiple reflection setup.
So if you elect to 'deviate', for example not to absorb front boundary reflections, makes sense to have a reason, i feel.
Again, there is evidence that the floor reflection is individually affecting timbre when using noise (single loudspeaker/multiple reflections), but no longer affecting timbre when using speech. No data for music.
Otherwise, given the rhetoric of so many publications, it seems near impossible to extract 'best practice' and make something useful happen.
In his book Floyd Toole write: “In a recent survey of recording control rooms (see link below) revealed a disturbing amount of variation in spectral balance among them. The differences were not subtle, especially at low frequencies.”
Further, here’s an excerpt of an AES paper on sound localisation:
Hartmann, "Auditory Localization in Rooms", PROCEEDINGS OF THE 12TH INTERNATIONAL AES CONFERENCE 1993, pps 35 - 39
There are implications of this localization research for stereophonic sound recording and reproduction. Because the steady-state localization cues in a room are discounted, a listener who is positioned away from the loudspeakers will not respond to steady-state cues for localization, but will localize on the basis of transients only. This is especially true if the room is rather reverberant. The perceived source may be at one of the two loudspeaker positions, or, if speakers are about equally distant, the perceived source may be between the speakers. It may even be where the mixdown engineer wanted it to be. On the other hand, our experience with the Franssen effect suggests that if the listener is close to the speakers, especially if the room is dry, then steady-state cues may play an increasing role. One expects, for instance, that the mixdown engineer listening to small loudspeakers on top of the mixing desk in a dry engineering room is getting some plausible steady-state cues that will lose their effectiveness in a large living room. Because of the plausibility hypothesis, the consumer gets a different mix of steady-state and transient cues than the engineer.
The idea that for a given room configuration there is a minimum onset rate, measured in units of pressure per unit time, required to trigger the precedence effect means that sonic images will seem to be better localized when a recording is reproduced at high level. Based upon the numbers obtained experimentally, one does not expect this to be a large effect for recorded sources that are “up front.” One expects this to he a factor for background strings which do not appear at high level on the recording and do not have abrupt onsets. Again, if the mixdown engineer is listening at high levels, which is how we normally imagine him or her, then the engineer is getting localization cues that will be lost in most reproduction; this lime the cues are weak transients.
So, for a start, control room acoustics is a moving target and second, the listening conditions at home are almost certainly not the same as in any control room, you will hence end up with a task impossible to fulfil: recreate control listening environment.
Of course, if you're inclined to the opinion that a studio listening environment is generally poor, you might prefer something like Mr Linkwitz' living room!
I don’t think that studio environment is poor. Control rooms are working environments so no one will use “natural absorbers” you find in living rooms such as heavy carpeting, absorbing furniture, drapes etc. Therefore, acoustic treatment is a must. However, I think that by no means control rooms set the standard for the acoustics to be recreated at home. Show me convincing evidence and I change my mind.
Be interesting to hear more about the room you created from scratch, Klaus, and where the best sounding room you ever heard was?
That room was built as an extension to our house. I thought now is the occasion to get the acoustics right. Bonello’s criterion for room dimension ratios was nicely in line with the concept of the Schroeder-frequency, so I went and made the calculations. Afterwards it turned out that the builder had made a mistake and built the room a bit larger than on the drawings, thereby messing up with Bonello’s first requirement. What shall I say, there was no room mode disaster, and then I came across these:
The walls were built from bricks, the floor was to be tiled, windows with double glaze, so I knew in advance that without any treatment that room would be catastrophic. I initially intended to use the compound baffle absorbers of Fraunhofer Institute of Constructional Physics but these were heavy (40 kgs each) and expensive. Then I discovered the fabric under tension ceiling. Metallic profiles are attached to the walls, the room is heated to about 45 degrees C, the synthetic fabric is clamped into the profiles, when cooling down the fabric shrinks and is tensioned. With some 26 cm air space above the result is a huge membrane absorber with high absorption coefficient well down into the bass range, lowering reverberation time to comfortable values and treating both vertical and horizontal modes. When playing sine tones the modes can still be clearly distinguished but so far I have found only 3-4 tracks among my records and Ceedees where a mode is actually excited.
Best sounding room I’ve heard? No idea, worst sounding is easier, friends of ours have a dining room with just table and chairs, some light curtains, wooden floor. Speech intelligibility is extremely poor, they are French (which is not my mother tongue) so when I’m at one end of the table and all of us are talking at the same time, I have real difficulties to understand what the person at the other end of the table is saying: cocktail party effect is definitely struggling.