Complete the paragraph
Complete the following paragraph by choosing correct alternatives from those given in the bracket.
(audible, 20 Hz, infra-sound, greater, 20,000 Hz, electrical signals, less, pressure)
Range of frequencies of sound which can be heard by the human ears is called ________sound. The range of audible sound is between_________to __________to . Sound of frequency less than 20 Hz is called ______Ultra sound has a frequency ______than 20,000 Hz. Human ear converts pressure variations in air into_________.