"No; we heard, I think, the sound of her guzla, but she
remained perfectly invisible."

All I could find out was that it is some kind of stringed instrument.

Oooh, ooohh ooooh. I think it's a Swedish fiddle. Look under guzle.

The sound was supposed to be coming from quarters of a mysterious eastern Meditteranean countess. I think I remember seeing something that suggested it was a bowed instrument, so at least somewhat similar to the one you suggest.