Example showing how to mute changing only one bit.

mute_transm.cpp

void TEA5767N::mute() {
  setSoundOff();
  transmitData();
}

void TEA5767N::setSoundOff() {
  transmission_data[FIRST_DATA] |= 0b10000000;
}

void TEA5767N::transmitData() {
  Wire.beginTransmission(TEA5767_I2C_ADDRESS);
  for (int i=0 ; i<6 ; i++) {
    Wire.write(transmission_data[i]);
  }
  Wire.endTransmission();
  delay(100);
}