Classical guitarist Cristina Galietto performs The Whistling Spider by Sergio Assad (b.1952). This comes via Knobloch Strings and their YouTube channel. The piece was dedicated to Galietto and this is the premiere video. Wonderful performance by Galietto with so many fun articulation and zippy characters to all the playful motifs. I have no idea what is creating the squeaky whistling in what looks like unpressed glissando sometimes with a stop. It must be unique to the strings. Ha, a mystery, a trick!
Cristina Galietto Plays The Whistling Spider by Assad
No trick. Just rub your finger along the string, works on my Nylgut strings.