The above is true, but 40 Hz is the generally accepted transducer sound wave. Look at the players who make these contraptions, and 40Hz is their rating. You can get different transducers, EG, 28Hz, 40Hz, et cet., but you will need a generator which sweeps thru the frequencies. That type of generator costs a fortune. The real key is the power. The HF you are looking at is no more than a "nominal" 35Watt. Compare that against a real 600W and apply the 1 gallon of liquid for every 100Watts of mojo.