Final answer:
The chorale melody in the fourth movement of Bach's cantata Wachet Auf is heard in the tenors singing the chorale melody in unison.
Step-by-step explanation:
The chorale melody in the fourth movement of Bach's cantata Wachet Auf is heard in the tenors singing the chorale melody in unison. This movement features the tenors prominently, with the other voices providing accompaniment. The melody is not heard solely in the strings or only in the basso continuo, but rather in the tenor voices.