Final answer:
Haydn surprises the listener in his "Surprise" Symphony by starting a movement softly and then suddenly inserting a loud chord played by the entire ensemble.
Step-by-step explanation:
The listener is surprised in Joseph Haydn's "Surprise" Symphony, which is Symphony No. 94, through a sudden and unexpected musical event. Specifically, Haydn plays with listeners' expectations by starting the second movement of the symphony very quietly and calmly, and just when everyone is settled into the gentle melody, he introduces a startlingly loud chord. This sudden loud chord is played by the entire ensemble, which creates a surprise effect that is both humorous and memorable.