演壇

1. Origins, structure, and basic meaning

• Structure: 演壇 (えんだん) is a platform or lectern used by a speaker. 演壇に立つ identifies a position, and 演壇の高さ identifies a dimension of the fixture.
• Basic usage: A lecturer stands at the platform; a staff member adjusts its height for the speaker.

2. Common pitfalls and similar expressions

• Position for a speaker and adjustable height
  • に marks where the person stands, while の creates a whole-attribute relation between the platform and its height. 演壇 does not name the act of speaking.