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Case study: Recordings of an orchestra

There were two performances before an invited audience. Both performances had the same orchestra and pop group. At the first concert light music was played and the performance was arranged in a traditional 'classical' layout. At the second concert pop music was played and a 'novel' layout was tried.

Noise levels within the brass and percussion sections of an orchestra can exceed 95 dB. In the traditional layout of the orchestra, players of quieter instruments seated in front of these sections can receive a significant noise exposure from these louder instruments. During the pop concert recording the orchestra experimented with placing the brass and percussion sections to the front of the orchestra. The woodwind and strings were on raised staging behind. Individual microphones were used for each player and the sound heard by the audience was amplified and balanced electronically. Players used headsets to hear backing tracks and clicks.

Clear, head-height screens, separating the pop musicians from the orchestra, provided some additional protection where pop and orchestra musicians were in close proximity.

To maintain the benefit of the physical noise controls the pop musicians and sound technicians were reminded of the need to moderate amplified sound levels on the stage. As a consequence the monitor speakers for the pop musicians gave a lower level than the pop musicians were accustomed to.

The table below compares the daily noise exposure of the orchestra during the 'classical' concert recording with a traditional layout of the players, and the noise exposure during the pop concert with the novel arrangement. Both events were at the same venue. The exposure in both cases arises from a full-length rehearsal and performance within the same day.

Comparison of daily noise exposure.

Player Traditional layout arrangement for 'classical' concert LEP,d dB Novel layout arrangement for pop concert LEP,d dB
Trumpet 92 93
Clarinet 91 80 (on back row of orchestra)
Violin 88 87
Viola 87 84
Cello 83 (at far edge of orchestra) 86 (in front of woodwind)

Commentary

The orchestra musicians had said that previous recordings of pop concerts had given much higher sound levels than classical recordings. Compared to a classical recording this experimental arrangement of the orchestra gave a reduced exposure for most string and woodwind players, and no increase in exposure for the brass players.

The rearrangement of the orchestra was viable because musicians were playing with backing tracks and clicks heard through headsets with electronic balancing of the sound from each instrument for the recording and audience. The additional microphones and sound equipment significantly increased production costs. The orchestra layout described here is unsuitable for a classical concert where players need to hear other orchestra sections or where the audience need to hear the quieter instruments acoustically (not amplified).

Illustrations of the two layouts:

'Classical' concert recording shows a traditional orchestra layout, which places the quieter section, the strings and woodwind, between the pop group and the orchestra's brass and percussion sections. Transparent acoustic screens were placed between the strings and the pop group's equipment but these did not provide enough protection from their loud amplifiers and monitors.

Novel layout for pop concert shows how the layout was changed to provide more noise protection for the orchestra. The strings and woodwind sections were tiered which moved them away from the noisiest area of the stage. The brass and percussion sections were situated down-stage and separated from the pop group's band by acoustic screens. These screens were placed far enough away from the brass so as not to cause any noise reflection but also to protect them from the loudness of the group's amplifiers.

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