Cavitation is the formation of tiny bubbles or cavities in a liquid due to changes in pressure. The frequency of sound waves that will create this effect depends on the type of material, but it typically falls within a range between 20kHz and 40kHz. Higher frequencies (above 40kHz) are generally more effective at creating cavitation than lower frequencies, as they cause greater disruption to the liquid's surface tension and allow for more efficient bubble formation. Additionally, higher frequencies tend to be more directional and can therefore better target specific areas for cleaning applications.