Ultrasound which is upper limit of human hearing is characterized by which of the following frequencies?

• A. Above 2 KHz
• B. Below 20 KHz
• C. Above 200 KHz
• D. Above 20 KHz

Answer: (D)

Ultrasound refers to a sound wave with a frequency greater than the upper limit of human hearing, which is generally over 20 kHz. In general, humans can hear sounds with a frequency between 20 Hz and 20 kHz.