In the age of music notation software, composers and arrangers can crank out music quickly, and for the most part, neatly. However, in their quest to get an arrangement out the door asap, arrangers can often cut-and-paste lines of music from one instrument to another. I don’t have a problem with this – I’d mostly likely do it myself, if I were pressed for time – but what often happens is that the material that’s brought in from another instrument is kept in the same clef as the original instrument. Often, this isn’t a huge deal. Violists read two clefs in their everyday lives: alto, and treble. Here is a visual guide to how alto clef fits in with treble and bass clef (what pianists read when they play):
Those note heads designate the open strings of the viola. As you can see, the viola spans roughly half of each of the treble and bass clefs. Because of this range, the alto clef, squarely in the middle, works best, because if provides from the least amount of ledger lines (lines added above or below the staff) in the most commonly used range of the instrument.
That low C that you see in the bass clef – that is our lowest note. Unless we tune down our C-string, we can’t physically play any lower than that. However, we can play well up into the treble clef, using many ledger lines – if we tried to notate those notes in alto clef, it would be impossible to fit them on the page! Therefore, we use treble clef quite a bit for the sake of readability and ease of music engraving (what it’s still called even though most music publishing long ago abandoned engraved plates for printing).
To make a long story a bit shorter, here is the received wisdom of orchestrating for the viola: use treble clef to enhance readability, and don’t go lower than the range of the violin (because many of us either play, or have played the violin, and going below G on treble clef puts us in territory where we can’t quickly read what the notes are).
So, back to our composer and arranger (mostly arranger) friends. They are on a tight deadline, and they cut-and-paste music from one instrument to another (or from a piano score to an instrumental score line), and the music is shoe-horned into the clef that the arranger has chosen for the viola part. Often, this is in treble clef, because they’re working from a treble clef source, and it’s easier for an arrange to quickly read (most people who don’t play viola or trombone aren’t super fluent in alto clef). Sometimes, this works great. Other times, not so much. When the arranger doesn’t proof their parts, we get stuff like this to read:
You can see that most of the chart is in treble clef – not a problem, usually, but at m. 47, we get the dreaded treble clef below-the-staff ledger line issue which makes all violists see red and post to twitter with #OrchestrationMatters hastags.
Please, arrangers, use alto clef for violists! And use treble clef only if it keeps our line within the staff or the normal range of the violin! Please, we beg you!