Dulcimer 2014
Several of the most common types of musical instruments are shown on the table as examples. If you have proficiency with a given musical instrument, you can add your proficiency bonus to any ability checks you make to play music with the instrument. A bard can use a musical instrument as a spellcasting focus. Each type of musical instrument requires a separate proficiency.
Source: System Reference Document 5.1 (Wizards of the Coast) · License: Creative Commons Attribution 4.0 / OPEN GAME LICENSE Version 1.0a details