The answer will depend on the actual compression format. Uncompressed PCM in a bank will remain at the source sample rate. Vorbis banks will be resampled at build time to the nearest of 8, 11.025, 16, 22.05, 24, 32, 44.1, 48. AT9 will be resampled at build time to 48. XMA will be resampled at build time if it’s above 48, otherwise it will be encoded at the source rate. When the sounds are played at runtime that will be resampled from their bank rate to the system rate (plus any pitch changes applied).
The runtime resampling defaults to linear and can be changed using System::setSoftwareFormat(), the bank time resampling is spline.