According to compatibility matrix, nordic BLE and audio shields cannot be used together.
This is maybe because of SPI bus conflict.
But sdcard shield also uses SPI, which can be used with audio shield.
Can anyone answer me that why nordic BLE cannot be used with audio shield?

The audio shield uses pins 2, 3, 4 and the Nordic BLE shield uses pin 2 for its interrupt output- that's tough to change to another pin(other than 3, but that doesn't help).