Sound waves that have a frequency less than 20 Hz are defined as.

Sound waves that have a frequency less than 20 Hz are defined as.

• A. Audible
• B. Ultrasonic
• C. Infrasonic
• D. Vibrational

Answer: (C)

Understanding sound frequency ranges helps classify waves. Humans typically hear from about 20 Hz up to 20 kHz; anything below 20 Hz falls into the infrasonic range, while frequencies above 20 kHz are ultrasonic. So a sound with frequency less than 20 Hz is infrasonic. Audible is the label for the range we can hear, and vibrational isn’t a standard category for this kind of frequency classification. Infrasonic waves occur in natural phenomena and in some animal communication, such as elephants using very low-frequency calls that can travel long distances.

Understanding sound frequency ranges helps classify waves. Humans typically hear from about 20 Hz up to 20 kHz; anything below 20 Hz falls into the infrasonic range, while frequencies above 20 kHz are ultrasonic. So a sound with frequency less than 20 Hz is infrasonic. Audible is the label for the range we can hear, and vibrational isn’t a standard category for this kind of frequency classification. Infrasonic waves occur in natural phenomena and in some animal communication, such as elephants using very low-frequency calls that can travel long distances.