(name v.s 'a') is it possible?

OMG, stop the madness!!! How could you have possibly written a 3000 line program without having the slightest clue regarding the most basic constructs of the language? Do yourself a favor, set this project aside for a while and learn the fundamentals of C++ programming.

Before you do, here's one more fish for you:

void playWav (char* name);

void setup() {
}

void loop() {
  //...
  //...
  playWav ("alarm");
  //...
  //...
}

void playWav (char* name) {
  char buffer [40];
  //..
  //..
  sprintf (buffer, "wav/%s.wav", name);
  file = new AudioFileSourceSD(buffer);
  //...
  //...
}

BTW, if the memory leak I warned you about shows up, it will make this problem seem like child's play. You'll get random crashes at random times in random locations and won't have a clue what's causing it. So, I'd make sure those dynamically-allocated objects eventually get deleted.

Now, go learn to fish.