A single clause that begins with one of these words is not a complete sentence. The conjunctive adverb goes between the two clauses it joins. Place a semicolon after the first independent clause and then the conjunctive adverb with a comma after it. A clause that begins with a conjunctive adverb remains independent, and so is a complete sentence. However, her hearing sharpened.
Semicolons join independent clauses without the use of a conjunctive word.
Use a semicolon alone between clauses when the clauses are closely related.