频率
事件重复出现的速率。当与振动相关时，假定事件以固定的时间间隔发生（即具有周期性）。在低频超声范围内，频率通常以赫兹（Hz）或千赫兹（kHz）表示。
应用于超声谐振器时，"频率"一般指特定振动模态的谐振频率。如无特别说明，"频率"指谐振器主模态的频率。例如，若变幅杆的主模态为轴向模态，则"变幅杆频率为 19852 Hz"这一表述表示轴向（主）模态的频率为 19852 Hz。
Frequency
The rate at which an event recurs. When associated with vibration, the assumption is made that the event occurs at regular intervals (i.e., it is periodic). In the low frequency ultrasonic range, frequency is usually expressed in Hertz (Hz) or kiloHertz (kHz).
When applied to ultrasonic resonators, "frequency" generally refers to the resonant frequency of a particular vibration mode. If not otherwise specified, "frequency" refers to the frequency of the primary mode of the resonator. For example, if the primary mode of a horn is the axial mode, then the statement "The horn frequency is 19852 Hz." indicates that the frequency of the axial (primary) mode is 19852 Hz.