I have two recommended methods on how to make a clear voice in terms of the physical movements of the larynx.
(1)Letting out voice slowly: By decreasing speed of the voice you can keep a steady balance of the lateral cricoarytenoid muscle, the transverse arytenoid muscle, the oblique arytenoid muscle, the posterior cricoarytenoid muscle, and the cricothyroid muscle. Moderate flexibility is necessary with these muscles, because they are difficult to control consciously.
(2)Put a whisper voice soon before (the beginning) letting out the voice: You can change the hardness of the vocal cords mucosa and the surrounding muscles, which will improve the blood circulation of the superior laryngeal artery in the larynx. Start vocalizing soft and smooth, focus and build up – then increase in volume and strength.
You can acquire a clearer high-pitched voice with a conscious awareness of the above methods.