For Patti Niemi, becoming a professional symphony percussionist meant first coming to terms with her anxiety. When percussionist Patti Niemi plays, you hear it. Down in the pit, among the San Francisco Opera Orchestra’s other musicians, there is no hiding the sound of her hitting the snare drum, bass drum, glockenspiel, marimbas, bells, or chimes… let alone the calculated crash of her favorite instrument, the cymbals.