Volume swelling is a musical crescendo (a gradual increase in volume of a musical passage).It is mainly used with electric guitar. This effect is also called as violining as it produces same sound as that of violin.
It is used by guitarist Eddie Van Halen, Jimmy Page, Steve Vai, Joe Satriani, Yngwie Malssteen, Slash and band like Radiohead and many more. This technique is heart of neo classical shredding (Yngwie Malssteen thing)
