Hospital corpsmen were previously trained at Naval Hospital Corps School, Great Lakes, Illinois until the 2011 Base Realignment and Closure Bill caused Hospital Corps School to be relocated to the Medical Education and Training Campus (METC) at Joint Base San Antonio, Texas.
characteristic of highness or lowness of a sound is called The frequency of a sound wave determines the pitch of the sound you hear. Remember that frequency is the number of waves passing a fixed point in a given period of time. A high-frequency wave with short wave-lengths, such as that produced by a tiny flute, makes a high-pitched sound.
Very generally with speech, low frequency vowel sounds carry the 'power' of the speech, whilst high frequency consonant sounds carry the information of the speech - If these high frequencies are lost, the acoustic power is still there and you can hear that someone is talking but you can't make out what is being said.