Sound is a versatile tool in our daily lives and scientific applications. It serves two primary functions: transmitting information and transferring energy. We can hear sounds in the frequency range of 20 Hz to 20,000 Hz, but there are also ultrasonic waves above 20,000 Hz and infrasonic waves below 20 Hz that have special applications.
超声波的频率超过20000赫兹，已经彻底改变了许多领域。在医学中，超声波成像让医生能够安全地看到人体内部，监测怀孕情况并诊断疾病。在工业中，超声波清洗利用高频振动来清除精密零件上的污垢和污染物，产生微小气泡来擦洗表面。