int buzzPin = 25, pwm_c = 0;
void setup()  
{        
  ledcSetup(pwm_c, 10000, 8);
  ledcAttachPin(25, pwm_c);
}

void loop()                     
{
  int octave = 4;
  delay(200);
  ledcWriteNote(pwm_c, NOTE_C, octave);
  delay(200); 
  ledcWriteNote(pwm_c, NOTE_D, octave);
  delay(200); 
  ledcWriteNote(pwm_c, NOTE_E, octave);
  delay(200); 
  ledcWriteNote(pwm_c, NOTE_F, octave);
  delay(200); 
  ledcWriteNote(pwm_c, NOTE_G, octave);
  delay(200);     
  ledcWriteTone(pwm_c, 0);
  delay(200);
}