Ultrasound decibels

Hol
Ok so what is your opinion on ultrasound decibels?
 Iv been told by a family member (she is a bit hippy and more of an all natural person) that for our babies ears, an u/s isnt good and is as loud as a live concert/festival is for us. And can cause hearing issues when the babies older....
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Im not wanting any more u/s's than whats needed, but i was just curious if its true. 
Im sure they wouldnt do it if it was unsafe for the baby?!....
​Anyway what do you think???