ok, I'm sorry
the shield is the adafruits wave shield Adafruit Wave Shield for Arduino Kit [v1.1] : ID 94 : $22.00 : Adafruit Industries, Unique & fun DIY electronics and kits
and this is my sketch
#include <AF_Wave.h>
#include <avr/pgmspace.h>
#include "util.h"
#include "wave.h"
int pirPin= 0; // Reading from digital pin 11 PIR sensor!
int val = 0;
AF_Wave card;
File f;
Wavefile wave;
void setup() {
// set up serial port
Serial.begin(9600);
pinMode(pirPin, INPUT);
// set up waveshield pins
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(0, INPUT);
// open memory card...........This part is necessary to set up and read SDcard!
if (!card.init_card()) {
putstring_nl("Card init. failed!"); return;
}
if (!card.open_partition()) {
putstring_nl("No partition!"); return;
}
if (!card.open_filesys()) {
putstring_nl("Couldn't open filesys"); return;
}
if (!card.open_rootdir()) {
putstring_nl("Couldn't open dir"); return;
}
putstring_nl("Files fuond:");
ls();
}
void ls() {
char name[13];
int ret;
card.reset_dir();
putstring_nl("Files found:");
while (1) {
ret = card.get_next_name_in_dir(name);
if (!ret) {
card.reset_dir();
return;
}
Serial.println(name);
}
}
void loop(){
val = analogRead(pirPin);
Serial.println(val);
if (val < 10) {
Serial.println("e vai!");
playcomplete("PEN3.WAV");
}
if (val > 11) {
Serial.println ("zitto");
}
delay (500);
// while (LOW==analogRead(pirPin)) {;}
// delay(5000);
}
void playcomplete(char *name){
playfile(name);
while (wave.isplaying);
card.close_file(f);
}
void playfile(char *name) {
// stop any file already playing
if (wave.isplaying) {
wave.stop();
card.close_file(f);
}
f = card.open_file(name);
if (f && wave.create(f)) {
wave.play();
}
}
but what mean this? : sample_12 = sample_16 >>4;
thank you 
f