Task: Question Answering
Input (English): Passage: While Raff was able to offer "practical suggestions [in orchestration] which were of great value to Liszt", there may have been "a basic misunderstanding" of the nature of their collaboration. Liszt wanted to learn more about instrumentation and acknowledged Raff's greater expertise in this area. Hence, he gave Raff piano sketches to orchestrate, just as he had done earlier with Conradi—"so that he might rehearse them, reflect on them, and then, as his confidence in the orchestra grew, change them." Raff disagreed, having the impression that Liszt wanted him on equal terms as a full collaborator. While attending an 1850 rehearsal of Prometheus, he told Bernhard Cossmann, who sat next to him, "Listen to the instrumentation. It is by me."Raff continued making such claims about his role in Liszt's compositional process. Some of these accounts, published posthumously by Die Musik in 1902 and 1903, suggest that he was an equal collaborator with Liszt. Raff's assertions were supported by Joachim, who had been active in Weimar at approximately the same time as Raff. Walker writes that Joachim later recalled to Raff's widow "that he had seen Raff 'produce full orchestral scores from piano sketches.'" Joachim also told Raff's biographer Andreas Moser that "the E-flat-major Piano Concerto was orchestrated from beginning to end by Raff." Raff's and Joachim's statements effectively questioned the authorship of Liszt's orchestral music, especially the symphonic poems. This speculation was debased when composer and Liszt scholar Peter Raabe carefully compared all sketches then known of Liszt's orchestral works with the published versions of the same works. Raabe demonstrated that, regardless of the position with first drafts, or of how much assistance Liszt may have received from Raff or Conradi at that point, every note of the final versions represents Liszt's intentions. 
Question: What is the last name of the person who sat next to Bernhard?
Output (English): Raff.