Aphonic and Unflappable

Aphonic adjective - Being without sound through injury or illness and thus incapable of all but whispered speech.

Unflappable and aphonic are semantically related. In some cases you can use "Unflappable" instead an adjective "Aphonic".

Unflappable adjective - Not easily panicked or upset.

Aphonic and unflappable are semantically related. Sometimes you can use "Aphonic" instead an adjective "Unflappable".