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Noise Exposure of Musicians at the National Ballet Orquestra. Alberto Behar, Cheng Qian, Willy Wong IBBME University of Toronto. Orlando, Feb. - 2010. Facts. The National Ballet has a 68 players strong orchestra. They are active 300 hr/year. (performances and rehearsals).
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Noise Exposure of Musicians at the National Ballet Orquestra Alberto Behar, Cheng Qian, Willy Wong IBBME University of Toronto Orlando, Feb. - 2010
Facts • TheNational Ballet hasa 68 players strong orchestra. • They are active 300 hr/year. (performances and rehearsals). • Performances are in the Four Seasons Centre for the Performing Arts in Toronto, a new Opera and Ballet house that opened in 2006.
The Survey - At the request of the Ballet Management - Presumption: risk of hearing loss, since levels may exceed 95 dBA - Assessment: performing noise exposure level measurements - During 10 performances of Sergei Prokofiev’s “Romeo and Juliet”, a particularly loud, 3 hour piece of ballet music
Procedures - Five dosimeters Quest Type 300 Calibrated at the Lab using QuestSuite soft and in the field using B&K calibrator 4230. - Procedures as per CSA Z107.56 3 dB exchange rate, measuring Leq, dBA, slow • Five players each time, some of them • more than once
Procedures (Cont). • - Dosimeter attached to the belt • - Microphone attached to the collar opposite to • the instrument • Special precaution regarding the cable – taped • on the back of the player
The orchestra pit Overhang Safety net
Number of tests. Brasses The orchestra pit. The orchestra pit.
Repeatability a) Same instrument and player: within 2dBA b) Only exception: Percussionist (3 dBA) c) Larger variations within same section across performances, especially strings (up to 8 dBA)
Normalizing the results Expressed as Leq,8 Leq, 8 = Leq, t - 10 log(t/T), dBA t = 300 hr/year Leq, 8 = Leq, t - 10 log(300/2000) = Leq, t - 8.2 dBA 8.2 dBA to be subtracted from the measurement results
Risk of hearing loss Risk for brass and flute players (85 dBA) after 40 years (ISO 1999)
Engineering controls i) Barriers ii) Raisers iii) Adding sound absorption
Hearing Protectors 1. Must be comfortable 2. Must have a relatively small attenuation 3. Must have flat attenuation …and of course MUST BE PART OF A HEARING CONSERVATION PROGRAM
The end Thank you! Any question?