Like a song in 2 Voices

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Across
  1. 3. plural noun
  2. 4. voice
  3. 5. song
  4. 6. (she) trills
  5. 7. expanse
  6. 8. part
  7. 9. echo
Down
  1. 1. boundless
  2. 2. songbird (birdsinger)
  3. 5. first (fem.)