MusingMuso Posted September 21, 2005 Share Posted September 21, 2005 In the Worcester Cathedral organ thread, I went off at something of a tangent concerning acoustics, and one discussion-board contributor suggested that we might open this as a new a separate subject; which I now do. To re-cap, mention was made of the Marcussen organ at Bridgewater Hall, and its' seemingly ineffective qualities at this particular location, which I suggested may be more to do with the design of the building tahn any particular fault on the part of the organ-builder. However, to get this discussion off on the right footing, perhaps it is necessary to start with a few basics. Where, I wonder, are the best acoustics to be found? We each have our favourite buildings, but I think that most people would generally agree that some of the very finest buildings in which organs are placed, are to be found in Holland. The churches may vary in size, and there will be obvious exceptions to the rule, but broadly speaking, smaller churches have a certain warmth and resonance thanks to extensive wooden interior furnishings and panelling material, and in the very large buildings, the general rule seems to be that of a single large room with either very shallow transpets, or none at all. It is clearly in such buildings that organ-tone is heard at its' best. Listen to an old baroque organ in such buildings, and there is not usually the slightest sense of shrillness or a lack of warmth, presence or fundamental. Like the carefully shaped body of a violin made by the master hand, the building becomes the great musical belly in which the music blossoms. Interestingly, when playing one of the best organs in Holland, there is a striking fact about the sound coming from the instrument, which seems to demonstrate a certain eveness in the relative volumes right across the audible spectrum, with no particulary audible "spikes" or attenuations. Things are less good in England; especially in the great cathedral churches, where deep transpets, changing roof lines and even stone screens break up the whole into a serious of "mini-acoustics" which often scatter the sound less than ideally. Nevertheless, a good organ will still sound like a good organ, even if it lacks the perfect definition of its' continetal counterparts in the Netherlands. Although the theory of acoustics is an enormous, complex and often subjective one, there can be little doubt but that modern buildings and building-materials often result in an acoustic which is often less than favourable to good, evenly spread organ-tone, and therefore presents special challenges to the art of the organ-builder and voicer. Having started the subject, I went back to my notes and some of the sources of information I had on disc. To cut a liong story short, the "absorption co-efficients" of modern building materials are radically different from more traditional materials such as stone, brick or glass. It isn't, it seems, simply a question of sound absorbency, but sound absorption within specific frequency bands. If we take stone as an example (much the same applies to brick and concrete), the absorption characteristics are not only very low; more importantly, they are very even across the audible spectrum. This means that even in traditional buildings with only the most modest acoustic, the rate of absorbency is uniform across the musical spectrum, by and large. Even carpets absorb energy across the spectrum evenly. Enter the world of the modern architect, who has to work around building regulations concerning firewalls, structural integrity, cost-saving building methods and structral integrity. Add to this the requirements of creature comforts such as soft-seat covers, carpets, lighting (requiring hidden ducting), heating and ventilation (again requiring hidden ducting) and decor, and what we have is an acoustic nightmare, which the acoustic engineers have to work around and modify, using computer models and scale-model acoustic test-beds. Enter the problem of modern materials, which may be fibrous board, fire-retardent laminates, plastics, foams, acoustic tiles, fibreglass etc etc. ALL these materials, almost without exception, have very specific characteristics, and taking a look at the absorbency co-efficients, what we find is an uneven absorbency across the audible spectrum. Some materials kill high-freqencies, whilst others kill the lower frequencies, but in the critical mid-frequencies, at which each of us is most sensitive, there can be enormous increases in energy absorbency, because these building materials were usually designed for offices and other industrial applications rather than for concert halls. For the moment, that is enough to consider, but if one thinks of the Royal Albert Hall, which has the worst natural acoustic in the world, it was the use of modern materials which came to its' rescue....so it isn't all bad news by any means, and the Arup Associates company who designed the Birmingham Symphony Hall, have shown just what can be achieved using modern materials and a classi concert-hall shape.. _ Link to comment Share on other sites More sharing options...
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