O Holy Night has been my favorite Christmas carol for at least two decades.  It embraces the relative minor and creates some nice dramatic moments, but I never realized how little of the original English carol by Adolphe Adam we actually sing.  Personally, the third verse is only vaguely familiar and I have never even read the second verse or refrain.  My lack of attachment to these texts in the middle of my favorite carol led me to make a bold decision.  Rather than set these unfamiliar texts as a part of my arrangement, I have incorporated a different carol in their place.  The second verse of Silent Night fits perfectly in the lyrical context of O Holy Night and the combination of these texts adds another dimension to the story.

My decision to incorporate Silent Night was immediately followed by another decision: I wanted to layer the two carols over top of each other.  I didn’t realize that the creation of this Christmas carol mash-up would result in at least 10 hours of work on 30 measures of music, but it was worth it.  The first challenge was the time signature.  O Holy Night is written in 6/8 (compound duple) and Silent Night is written in 3/4 (simple triple).  I decided to use the triple aspect of each piece to fit them together, elongating the rhythm of O Holy Night so the one of its 6/8 bars would take the same amount of time as two 3/4 bars of Silent Night.  I created the transition to 3/4 with a 4-bar phrase in which the eighth note beat stays the same.  This section introduces the Silent Night theme several times and moves to the dominant key signature (G-major).
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I wanted to keep the lyrics from becoming jumbled so I decided to write the melody to O Holy Night on “Lo” in the Soprano I range while Silent Night’s lyrics are sung by the Alto I’s.  The Soprano II and Alto II parts serve the purpose of filling in the chords that tie the two melodies together.
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The polyphony of these melodies was difficult because their phrases are different lengths and there were several moments of unpleasant dissonance between the two.  I solved this problem by altering a few rhythms and offsetting the start of each phrase.  The second phrase of “Silent” begins nine bars into “Holy’s” first phrase and the third phrase of “Silent” begins four bars into “Holy’s” second phrase.  This section still has a definitive break at the end of “Holy’s” first phrase with a crescendo on a G-major seventh chord.  O Holy Night resets  in the relative minor as Silent Night continues its second phrase.
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The piece also grows in complexity at this point as the Alto II begins singing the lyrics in parallel thirds and sixths with the Alto I.  This creates text painting on the lyrics “Heavenly hosts sing Alleluia” and emphasize the most important part of the lyrics, “Christ, the Savior, is born.”
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Due to the offsetting of the phrases, “Silent” ends earlier than “Holy,” but I utilized this as an opportunity to begin the complex key change that will move a tritone to Bb-minor.  In measure 83, the Alto II restates the third phrase of “Silent” in F-major, introducing our ears to the F-natural and B-flat of the next key signature.  This all occurs while the “Holy” melody concludes.  The voices then come together with a 4-bar transition that moves to the new key and puts the piece back into 6/8 (still keeping the eighth note consistent).
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This section was incredibly challenging to piece together but I am incredibly pleased with the powerful message created by the combination of these two pieces.  Was I right to incorporate “Silent Night” into this arrangement or should I have taken the simpler route of setting another verse of “O Holy Night” in a different style?  Let me know your thoughts below!