const int numberOfKeys = 7;
int keys[numberOfKeys] = { 6, 9, 10, 11, A2, A3, A4 };
int notes[numberOfKeys] = {1046, 1175, 1319, 1598, 1760, 2093, 2349};

int speaker = 5;                    // name of the speaker key
int touchValue;                     // will store sensor readings

void setup() {
    // set all keys to be inputs
    int i = 0;
    while (i < numberOfKeys)
    {
        pinMode(keys[i], INPUT);
        i = i+1;
    }
    pinMode(speaker, OUTPUT);       // set speaker to be an output
    Serial.begin(9600);             // initialize the communication
}

void loop() {
    int i = 0;
    while (i < numberOfKeys)
    { 
        checkPianoKey(keys[i], notes[i]); 
        i = i+1;
    } 
    Serial.println(); 
    delay(100); 
} 

void checkPianoKey(int key, int note) { 
    touchValue = readCapacitivePin(key); // read touch sensor value 
    Serial.print(touchValue);            // send value to the computer 
    Serial.print("\t");                  // send a tab 
    if (touchValue > 1)                  // if the key is pressed
    {
        tone(speaker, note);             // play a note
        delay(100);                      // wait for 1/10th of a second
    }
    else                                 // if the key is not pressed
    {
        noTone(speaker);                 // stop playing the note
    }
}