When comparing the stylopharyngeus to the stylohyoid muscle, it is easier for the stylopharyngeus muscle to become hard.
There are similarities between the two muscles as well as differences. Both the stylopharyngeus muscle and the stylohyoid muscle suspend the larynx. The stylohyoid muscle is associated with the stylohyoid ligament, but the stylopharyngeus muscle does not have any ligament associated with it.
The stylopharyngeus muscle is needed to contract and suspend the larynx. The stylohyoid muscle does not need to contract. This is because the associated stylohyoid ligament assists and supports it to suspend the larynx.
The stylopharyngeus muscle hangs and contracts to change the position of the larynx. The stylopharyngeus muscle just contracts to change the position of the hyoid bone.
Therefore, its easier for the stylopharyngeus muscle to get tired and stiff, in comparison to the stylohyoid muscle. which makes the high larynx. This means the larynx goes up, pushes the hyoid bone up to narrow the space of the resonance chamber creating a loose voice echo.
Note1:The larynx floats in the air within human hard tissues such as bone, cartilage or teeth.