The Sound Book: The Science of the Sonic Wonders of the World Read Online Free PDF

had rhythm or any kind of speed to it would be completely lost there because every event carried on for long after it was supposed to have ended. It reminds me of when we were at art school, we had a model who was very very fat. We used to say it took her 20 minutes to settle, she was impossible to draw. Well playing fast music in a lot of reverberation is a bit like that. 16
    The desirable amount of reverberation depends on the music that’s being listened to. Intricate chamber music by Haydn or Mozart was composed to be heard in courts and palaces, so it works best in smaller spaces with shorter reverberation times—say, 1.5 seconds. The French romantic composer Hector Berlioz wrote about hearing Haydn and Mozart played “in a building far too large and acoustically unsuitable,” complaining that they might as well have been played in an open field: “They sounded small, frigid and incoherent.” 17
    For romantic music by Berlioz, Tchaikovsky, or Beethoven, more reverberance is needed than for chamber music—say, a reverberation time of about 2 seconds. Organ and choral music demands even more. As renowned American concert organist E. Power Biggs said, “An organist will take all the reverberation time he is given, and then ask for a bit more . . . Many of Bach’s organ works are designed . . . to explore reverberation. Consider the pause that follows the ornamented proclamation that opens the famous Toccata in D minor. Obviously this is for the enjoyment of the notes as they remain suspended in the air.” 18
    The Royal Festival Hall in London was built as part of the Festival of Britain in 1951, which was meant to help cheer up the nation after years of rationing and austerity during and after the Second World War. 19 While critics adored the building, reviews of the acoustics in the concert hall were mixed, with an eventual consensus forming that the reverberation time was too short, being only 1½ seconds. In 1999, the conductor Sir Simon Rattle said, “The RFH is the worst major concert arena in Europe. The will to live slips away in the first half hour of rehearsal.” 20 Hope Bagenal was the original senior acoustic consultant for the hall. Surprisingly, he was not a scientist by training. Acoustic engineer David Trevor-Jones wrote that Bagenal’s “broad, liberal education” was important because it gave him “the inquisitiveness and . . . competence to take up as much of the physics of acoustics as he needed.” 21 Sabine’s equation would have shown Bagenal that there were two solutions to the hall’s dry acoustics. The first was to increase the size of the room, allowing more space for the sound to bounce around. Raising the roof would have been effective but impossibly expensive. The second solution was to reduce the acoustic absorption in the room. In a concert hall, the audience is responsible for most of the absorption. Bagenal recommended removing 500 seats to increase the reverberation time, but this was not done. 22 Instead, a revolutionary solution was sought: to use electronics to artificially enhance the acoustics.
    In the ceiling of the hall, microphones were mounted inside pots to pick up sound at particular frequencies. The electronic signals from the microphones were then amplified and fed to loudspeakers elsewhere in the ceiling. The sound circulated around a loop, going from microphone to loudspeaker through the electronics, and then from loudspeaker to microphone through the air. This setup sustained the sound for longer in the hall, creating artificial reverberation. This was a remarkable feat of engineering, considering the crude electronics available in the 1960s. The mastermind behind this assisted resonance system was Peter Parkin, who began working in acoustics in World War II, helping to defeat underwater acoustic mines. For his work on the Royal Festival Hall, Parkin had a dedicated telephone line from the hall to