<prompt> Threshold of hearing in a young normal adult is ?0 dB10 dB20 dB30 dB  <response>: Ans. isai.e.,0 dBAudiometric zeroThreshold of hearing, i.e. The faintest intensity which a normal healthy person can hear will vary from person to person.The International Standards Organisation ISO adopted a standard for this, which is represented as the zero level on the audiometer 0 dB.According to ISO, audiometric zero is the mean value of minimal audible intensity in a group of normally hearing healthy young adults. 