Help creating a sound-sensing LED display

Woops, sorry about that. Heres the code that I currently have set up for Knock Sensor:

/* Knock Sensor
 * ----------------
 *
 * Program using a Piezo element as if it was a knock sensor.
 *
 * We have to basically listen to an analog pin and detect 
 * if the signal goes over a certain threshold. It writes
 * "knock" to the serial port if the Threshold is crossed,
 * and toggles the LED on pin 13.
 *
 * (cleft) 2005 D. Cuartielles for K3
 */

int ledPin = 13;
int knockSensor = 0;               
byte val = 0;
int statePin = LOW;
int THRESHOLD = 100;

void setup() {
 pinMode(ledPin, OUTPUT); 
 beginSerial(9600);
}

void loop() {
  val = analogRead(knockSensor);     
  if (val >= THRESHOLD) {
    statePin = !statePin;
    digitalWrite(ledPin, statePin);
    printString("Knock!");
    printByte(10);
    printByte(13);
  }
  delay(100);  // we have to make a delay to avoid overloading the serial port
}

I want to set it so that each Knock turns on the light but turns it off as well right after.

However, I don't think the Piezo sensor is the right tool to use for my project, since it only picks up direct almost physical "taps". Perhaps a microphone.

Thanks for the insightful Grumpy!