螺柱面
连接螺柱伸出的谐振器表面。该表面通常是输入面。（换能器没有螺柱面。）该表面构成谐振器（如变幅杆）与其配对驱动谐振器（如增幅杆）之间的连接面。
注意：螺柱面通常是谐振器最靠后的表面。但对于采用凸台的变幅杆，凸台向后延伸超出螺柱面。
Stud surface
The resonator surface from which the coupling stud protrudes. This surface is usually the input surface. (Transducers have no stud surface.) This surface forms the joint between the resonator (e.g., the horn) and the mating driving resonator (e.g., the booster).
Note: the stud surface is usually the rear-most surface of the resonator. However, for horns that use risers, the riser extends rearward beyond the stud surface.