Accomplished young ladies in the Regency period were expected to excel at music, specifically the piano forte (or fortepiano).
While this picture depicts a far grander salon (Le Petit Trianon), the Musgroves would have been able to afford very good instruments and the character of Louisa suggests she would have demanded them.
The sound quality differed on the piano forte, an early version of a piano. The octave range also was smaller.
Here is an example of an early 19th century song for the piano such as the misses Musgrove might have learned to play: