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stood some yards away. These were all linked to analyzers, whose screens showed graphs of jagged lines sloping from top left to bottom right, characteristic of decaying sound. Normally, acoustic engineers use this equipment to examine whether walls permit too much sound to leak between neighboring houses, or whether the reverberance of a classroom will be too great, undermining the teacher’s lessons.

    Figure 1.1 Loudspeaker used to test Hamilton Mausoleum, with cupola above.
    Bill gave a signal, and I quickly stuck my fingers in my ears to protect my hearing. The loudspeakers roared into action, blasting out a growling noise, which even with my ear canals blocked sounded immensely powerful. After 10 seconds, Bill suddenly cut the loudspeaker and measured the noise decay while I quickly unblocked my ears so that I could enjoy the swirl of reverberation. The massive solid walls reflect sound very efficiently, and it took a long time before the noise completely disappeared. The initial overwhelming hissing roar morphed into a rumble that moved above my head, disappearing and dying away up near the cupola. There was a brief moment of silence before the assembled acoustic experts broke into fevered discussions.
    What was the reverberation time in the Hamilton Mausoleum? Since it is a large space constructed mainly of stone, the reverberation time is very different at low and high frequencies. At low frequency—say, 125 hertz, which is an octave below middle C (a frequency typical of a bass guitar)—the reverberation time was 18.7 seconds. For midfrequencies it was just over 9 seconds. 29 Impressive, but if it is the longest reverberation in the world, I would be very surprised.
    The midfrequencies are where speech is the most powerful, where our ears are the most sensitive, and hence where reverberation times are the most important for clear hearing. No wonder any ideas of holding ceremonies in the chapel were abandoned. Someone talking in a normal way says about three syllables every second. At that rate of speaking in the mausoleum, you utter several words before the first one dies away 9 seconds later. Inevitably, the sounds from many different words mingle and merge. Speech in the chapel is not too bad if you have a conversation with someone close by, because the direct sound from a nearby voice is much louder, making it easier to ignore the reflections. Speaking more slowly also helps. But once you get too far away from someone you want to talk with, the direct sound is less than the reflections, and the reverberation fills in the silences between the syllables, blurring the peaks and troughs in the sound wave and making the speech unintelligible.
    S ome cathedrals are ten times bigger than the chapel at the Hamilton Mausoleum, and a larger size should mean a longer reverberation time, according to Sabine’s equation. The vast, visually imposing cathedrals, built to glorify God, naturally have awe-inspiring acoustics. The sonic qualities are associated with spirituality. The excessive reverberation forces the congregation into silence or hushed whispers, because otherwise speech is rapidly amplified by reflections and creates an ungodly cacophony. During services, the music and words appear to wrap around you like the omnipresent God being worshipped. The acoustic has also influenced services, as the use of chanting and the slow liturgical voice counters the muddy speech in such reverberant spaces. 30
    Many centuries ago, the priest would stand in the chancel, almost cut off from the congregation in the nave. Typically, only a small opening above the chancel screen and below the tympanum would allow sound to reach the churchgoers. The priest would chant facing the altar, his back to the worshippers, so any speech reaching the congregation would be a mush of reflections, with all sound arriving indirectly via reflections off the walls and ceiling. Mind you, with the service mostly in Latin it could be argued