This is more difficult than it sounds as the wavelength varies with the speed of sound, which varies with environmental factors such as temperature and altitude. Significant studies have been made with such devices including into contactless chemistry and the levitation of small animals.
It's harder than it seems because the wavelength shifts depending on the speed of sound, which is influenced by things like temperature and altitude. There have been many studies done with these devices, including research into contactless chemistry and levitating tiny creatures.