From the linked paper: 'Gunther Schuller (b. 1925), an influential horn player, writes: “The timpani’s spreading wave-lengths back up through the horn, violent

From the linked paper: 'Gunther Schuller (b. 1925), an influential horn player, writes: “The timpani’s spreading wave-lengths back up through the horn, violently jarring the player’s lips. Under these conditions split notes abound and what notes can be played develop a strong rasp. A half minute of this and the horn player will retain no sensitivity in his lips” (1962). ... This proximity effect with the timpani has also been highlighted as a potential source of injury to horn players (Horvath, 2010), where “the impact of the timpani on the horn is an extremely direct and painful one” (Schuller, 1962), “like being hit in the mouth” (Buckle, 2008), and “will also negatively affect endurance” (Hill, 2001).'