int current;
int highest = 350;
int latchPin = 8;
int clockPin = 12;
int dataPin = 11;
int volume[9] = {0b00000000, 0b00000001, 0b00000011, 0b00000111,
                 0b00001111, 0b00011111, 0b00111111, 0b01111111,
                 0b11111111};
                 
void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  current = map(analogRead(A0), 0, highest, 0, 9);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, LSBFIRST, volume[current]);  
  digitalWrite(latchPin, HIGH);
}