• Question: why do our eardrums perfitrate under pressure form a force?

    Asked by ryantm to Helen, Jenni, Mark, Martin, Stu on 23 Jun 2011.
    • Photo: Jenni Tilley

      Jenni Tilley answered on 21 Jun 2011:

      For the same reason you damage a drum if you hit it too hard. The body is only as stiff and strong as it needs to be – it adapts to the regular forces we apply to it. The ear drum is only designed to withstand small amounts of force . It also needs be flexible enough to bend and deflect enough to pick up small sounds, so it’s really not very stiff. If you hit it with sound waves or pressure waves that are larger than those it’s designed to withstand it breaks

    • Photo: Helen O'Connor

      Helen O'Connor answered on 23 Jun 2011:

      and water pressure is more intense than air pressure: so diving 33 feet beneath the surface of water is the same as rising 80,000 feet in the air. http://www.livestrong.com/article/346264-perforated-eardrum-from-scuba-diving/

    • Photo: Mark Burnley

      Mark Burnley answered on 23 Jun 2011:

      Interestingly, pressure changes can damage other tissues, sometimes with fatal consequences. Race horses, and it appears some very highly trained athletes, rupture their “blood gas barrier” during very high-intensity exercise. This is due to negative pressures inside the lung caused by breathing in and high pulmonary artery pressure caused by very high cardiac output. This results in bleeding into the lung, which is sometimes seen in race horses, and some athletics coaches of times past would stay “run until you taste blood”. They were exaggerating, but not by much. Humans don’t bleed into the lungs but increased protein concentrations suggest that the pressures were close to causing blood-gas barrier failure.

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