• Question: How many decibels does it take to levitate an object, and can you hear it?

    Asked by anon-74192 to Tatsuki on 29 Apr 2020.
    • Photo: Tatsuki Fushimi

      Tatsuki Fushimi answered on 29 Apr 2020:

      Thank you for your question! I think the minimum acoustic pressure required to levitate small expanded-polystyrene balls (EPS) with a radius of 1 mm is about 1000 Pa (154 dB).

      If you want to levitate a larger object (about 24 mm) you will need about 6000 Pa (169 dB).

      Either of the acoustic pressure amplitude is intolerable for humans if we can hear them. But, we utilize ultrasound (frequency beyond 20 kHz; typically around 40 kHz). Humans cannot hear these sound frequencies, so it is quite safe to stand next to it (we still avoid putting ears in to the levitator though!).

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