section_path: Frequency/Ultrasound
section_name: Ultrasound
paragraph_text: Ultrasound
  
  Ultrasound is sound waves with frequencies higher than 20,000 Hz. Ultrasound is not different from audible sound in its physical properties, but cannot be heard by humans. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.
  
  Medical ultrasound is commonly used for diagnostics and treatment.