Complex sentence: The announcements on the R188 cars were originally by Annie Bergen, but portions of her original recordings were re-recorded by either Catherine Cowdery or Kathleen Campion, the voices of the R143 and R160 car announcements, respectively.
Split into simpler sentences: The announcements on the R188 cars were originally by Annie Bergen. However, portions of her original recordings were re-recorded by either Catherine Cowdery or Kathleen Campion, the voices of the R143 and R160 car announcements, respectively.