when portions of his left cortex deteriorated, the composer maurice ravel selectively lost his sense of pitch while retaining his sense of timbre, a deficit that inspired his writing of bolero, a piece that emphasizes variations in timbre

이문장이요 해석은 매끄럽게 되는데 문제는 a deficit 이 어디에 속해있는 단어인가요?.. while retaining his sense of timbre 로 문장이 끝났어야 했는데 어떻게 갑자기 a deficit이 등장했는지??