Final answer:
The loud chord after the solo statement of the idée fixe represents emphasis on the idée fixe.
Step-by-step explanation:
The loud chord immediately after the solo statement of the idée fixe represents emphasis on the idée fixe. The idée fixe is a recurring musical theme that represents the beloved in Hector Berlioz's composition, Symphonie fantastique. The loud chord serves to draw attention to this recurring theme, highlighting its significance and emotional impact.