I personally find the voices added to the gba version extremely annoying and overused. This patch removes both Mario and Luigi's voices and a few other sounds which were not present in the SNES version.
Super Mario Advance 2 - Super Mario World (U) [!].gba
CRC32: 5206880A
MD5: 2F660377581B7E48C06131F56C791B72
SHA-1: 5101DDF223D1D918928FE1F306B63A42ADA14A5E
-------------------------------------------------------------
0402 - Super Mario Advance 2 - Super Mario World (E) (M4).gba
CRC32: FCFEF343
MD5: F877B87F140945AD93CFCE50411507C0
SHA-1: 199A5A01BD3F56FBA9A701062EDBCF57E1528A0C