Which term describes sounds with frequencies below 15 hertz?

Which term describes sounds with frequencies below 15 hertz?

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

Answer: (B)

Understanding how sound frequencies are named helps here: human hearing generally covers about 20 Hz to 20 kHz. Frequencies that lie below the audible range are called infrasonic. Since 15 Hz is well under the lower limit of what people can hear, it fits the infrasonic category. Ultrasonic refers to sounds above the audible range (above ~20 kHz), which we can’t hear. Audible describes sounds within human hearing. Subsonic is usually about speeds below the speed of sound, and isn’t the standard label for low-frequency audio. So the term for sounds with frequencies below 15 Hz is infrasonic.

Understanding how sound frequencies are named helps here: human hearing generally covers about 20 Hz to 20 kHz. Frequencies that lie below the audible range are called infrasonic. Since 15 Hz is well under the lower limit of what people can hear, it fits the infrasonic category. Ultrasonic refers to sounds above the audible range (above ~20 kHz), which we can’t hear. Audible describes sounds within human hearing. Subsonic is usually about speeds below the speed of sound, and isn’t the standard label for low-frequency audio. So the term for sounds with frequencies below 15 Hz is infrasonic.