The U.S. Navy (LINK) classifies sonar according to the following bands:

• Low Frequency (LF): Up to 1 kHz
• Medium Frequency (MF): 1 to 10 kHz
• High Frequency (HF): Above 10 kHz

Human hearing is roughly between 20 Hz and 20,000 Hz (0.02 kHz to 20 kHz), leading to the next set of classifications:

• Infrasonic: 0 to 20 Hz (0 kHz to 0.02 kHz)
• Sonic: 20 Hz to 20 kHz (0.02 kHz to 20 kHz)
• Ultrasonic: Above 20 kHz