Why does singing high notes seem to strain my vocal chords more than low notes?

Higher pitch, higher tension.

1. Why does my voice strain when I sing high?
2. What happens to vocal cords on higher notes of singing?

Why does my voice strain when I sing high?

When you sing, you may subconsciously feel that you need to control your voice with the muscles that you can consciously control. So you activate your throat muscles and this creates strain in your throat as you try to control the notes you sing.

What happens to vocal cords on higher notes of singing?

This affects the quality of the sound. For lower notes, the folds vibrate slower and therefore can remain shorter and thicker. For higher notes, the folds vibrate faster. It can be easier to allow just the edges of the folds to vibrate, meaning the TA Thickening Muscle will be have to be less active.