“In ‘Wicked,’ for instance, Mr. Brohn selected woodwinds and harps to convey ‘the swirling girly fantasy’ of the good witch Glinda’s entrance inside a bubble, he told a website dedicated to the musical’s composer, Stephen Schwartz. For ‘I’m Not That Girl,’ which is sung by Elphaba, the green-skinned wicked witch of the West, Mr. Brohn used muted strings, a harp and acoustic guitars to stress its melancholy mood.”