176 Recording Studio Design of the rooms. Wood, plaster, concrete, soft stone, hard stone, metal, glass, ceramics and other materials all have their own characteristic sound qualities. Within the range of current response specification, it may be almost impossible to differentiate between the response plots of rooms of different materials in terms of determining from which materials they were made. Yet the ear will almost certainly detect instantly a woody, metallic, or `stony' sound. In gen- eral, all the above materials are suitable for the construction of live rooms, and it is down to the careful choice of the designer to decide which ones are most appropriate for any specific design. The overall sound of the rooms, however, will tend to have the self-evident sound quality associated with each material. Wood is generally warmer sounding than stone, and hard stone is generally brighter sounding than soft stone. Geometry and surface textures also play great parts in the subjective acoustic quality. 6.4.1 Room character differences For this discussion, live rooms should now be split into two groups; reflective rooms and reverberant rooms. The former tend to have short reverberation times, but are characterised by a large number of reflexions which die away quickly. The reverberant rooms tend to have a more diffusive character, with a smooth reverberant tail-off. The reflective `bright' rooms also often employ relatively flat surfaces, though rarely parallel, and they often contain a considerable amount of absorption to prevent excessive reverberant build-up. The reverberant rooms on the other hand tend to employ more irregular surfaces and relatively little absorption. It is possible to combine the two techniques, but the tendency here is usually towards rooms which have very strong sonic signatures, and consequently their use becomes more restricted. The question often seems to be asked as to why flat reflective surfaces in studios usually sound less musical than they do in the rooms of many houses or halls. Notwithstanding the isolation shell problem, studios rarely have the space-consuming chimney breasts, staircases, furniture, and other typical domestic artefacts. These things are all very effective in breaking up the regularity of room reflexions, but studio owners usually press designers for every available centimetre of space. As mentioned in Section 5.3.4, it would seem that far too many of them are more interested in selling the studio to their clients on the basis of floor space rather than acoustic performance. (Never mind the sound, . . . look at the size!) Perhaps this is to a large degree the fault of the ignorance of the clients as much as that of the studio owners. There is possibly too much belief today in what can be achieved electron- ically, and the importance of good acoustics is still not appreciated by a very large proportion of studio clients. Of course, those who do know tend to produce better recordings, by virtue of having had the luxury of better starting conditions, and leave the mass market wasting huge amounts of time trying to work out exactly which effects processor program they used in order to get that sound. The answer of course is that good recorded sound usually needs little or no post-processing, unless, that is, the processed sound is the object of the recording. There are almost no absolute rights or wrongs in terms of live room design, and it seems that whatever a designer provides, there will always be people coming along who have heard `better' elsewhere. Nevertheless it is also