alleryStart learning →Sounds below 20 Hz frequency are called
AUltrasonic sounds only
BInfrasonic sounds
CSupersonic sounds only
DAudible sounds only
Answer & Solution
Correct answer: B. Infrasonic sounds
1. The chapter section on infrasonic sounds defines them.
2. Frequencies below 20 Hz cannot be heard by humans.
3. Elephants and whales can produce and detect them.
4. So option A is correct.
_Source: Selina Concise Physics Class 9, Ch 8 Sound (Mistral OCR'd PDF), section on infrasonic_
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