The sitar is a plucked string instrument used in Hindustani classical music. A striking feature of the sitar is its double layer of strings. While there are usually 6 or 7 'played' strings on the top, there are 11 to 13 'sympathetic' strings (tarabdar) running underneath the frets. These sympathetic strings are never plucked directly. Instead, they are tuned to the notes of the Raga being played. When the player plucks a melody note on the main strings, the corresponding sympathetic string begins to vibrate on its own through acoustic resonance. This creates the shimmering, echoing, and 'lush' background sound that is the hallmark of the sitar. The curved frets are also unique; they are raised high above the neck, allowing the player to pull the string sideways to 'bend' the note, a technique called 'meend' that mimics the sliding nuances of the human voice.