My academic department recently put together a lip sync video of “Blue Christmas.” For part of my time, I played the alto saxophone.
I first took up the instrument in middle school and played regularly through college in band, marching band, and pep band. Even with this familiarity, miming playing a song was difficult. I did not know what key it was in. I could move my fingers to the music and go up or down when needed but this does not mean I was close to the right notes. As a musician, it felt strange. (Yes, if I had a little more time I could have figured out the key of the song and transposed for the saxophone.)
I have thought about this numerous times before with television shows and movies when they depict people playing instruments. Since I play piano and can strum a few guitar chords, these performances especially catch my attention. For piano, they often show separate shots of playing the keys and the person sitting at the piano with their hands hidden. For guitar, you can sometimes see which chords are being played or see the strumming patterns. But, this too can be hidden or obscured.
All of this reminds me that musicians like the Beatles sometimes had to mime playing their instruments on television because of particular rules. In these situations, I assume professional musicians with all of their training could play without sound. In music (and much of the rest of life), practice makes perfect, even if it is not a full performance.
Perhaps the normal viewer does not think about this much. This may matter more in films where music is at the heart of the story but if you do not watch too closely or the shots do not really show much, any issues may not be noticeable. The music generally sounds fine, regardless of what the musicians on screen is depicted as doing. And if people want to see musicians play, there are many fine music videos and recorded performances available for viewing. Still, this ended any dreams I might harbor of adding saxophone to numerous lip syncing videos – I will need to leave that to the professional musicians and cinematographers.