Two or more vibration generators may introduce {TAIL ~ vibrations} with {HEAD ~ different frequencies} into the chemical bath liquid and at different angles 
Two or more vibration generators may introduce { TAIL ~ vibrations } with { HEAD ~ different frequencies } into the chemical bath liquid and at different angles
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH