Size and weight of the vocal cords, and the resultant sound, is very important for healthy singing in accord with the laws of nature. For each and every pitch that we sing, there is a specific length, width, and depth of the vocal cords vibrating to produce that pitch with a feel of weight that is heavier or lighter depending on where we are in the pitch range. If for example we were to try to sing a middle C on the piano but did so with the vocal cord adjustment of the A below the middle C, then the size of our vocal cords would be physically too large for the pitch being sung, the sound and feel would be too heavy. The vocal cords cannot stay in healthy vibration when we have too much length, width, and depth being engaged for a higher pitch, or too little engaged for a lower pitch. In the case of too much cord engaged and being too heavy, then we might try to boost the pitch by adding volume and pushing air. This only works for a time, and then we are in trouble as our cords dilate or separate. The cords cannot handle the strain and get locked out; unable to approximate or move well. However, if our muscles are balanced, then as we ascend the scale we will be smaller and lighter. As we descend the scale we will be little bit by little bit larger and heavier, all corresponding to the actual size of the vibrating vocal cords!