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Sounds above 20000 Hz frequency are called

ASupersonic sounds only
BInfrasonic sounds only
CUltrasonic sounds
DAudible sounds only
Answer & Solution
Correct answer: C. Ultrasonic sounds
1. The chapter section on ultrasonic sounds defines them. 2. Frequencies above 20 kHz are inaudible to humans. 3. Bats and dolphins use ultrasonic waves to navigate. 4. So option A is correct. _Source: Selina Concise Physics Class 9, Ch 8 Sound (Mistral OCR'd PDF), section on ultrasonic_
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