<prompt> Normal voice heard from 1 meter, intensity of sound reaching ear is -20 dB40 dB60 dB80 dB  <response>: Normal conversation produces 60-70 dB. Whisper 20-30 dB. Mechanical damage at 150-160 dB REF. PARKS TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 22nd EDITION. PAGE NO - 688 