Question

the sound wave of frequency lower than 20 kHz is ______ sound
please help.........

Answer 1

Answer:

infra sonic sound is the correct answer to the question

Explanation:

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Answer 2

Answer:

lower than 20 kHz: audible sound

above 20 kHz : ultrasonic

below 20 kHz : infrasound

so the correct answer is audible sound..