Can you tell the difference between a violin and a viola just by listening to them?
Generally even a non-musical expert would be able to tell the difference between a violin and a viola just by listening to the two of them side by side. Violins are the soprano voice of the orchestra and therefore can produce the highest sounds. No other instrument in a string orchestra can get as high as the violin can. A violia looks very similar to a violin, but has one string lower than a violin and does not have the top string. The viola is the alto voice of the string orchestra and produces a much mellower and richer tone than a violin.
