Juan and giancarlo are opera singers. juan is a tenor and giancarlo is a baritone. tenors sing with higher-pitched voices than baritones. with respect to this fact, the sound waves corresponding to giancarlo's voice are lower in than those corresponding to juan's voice; that is, they are lower

The missing words are (respectively):

frequency and hertz

To complete the sentences:

the sound waves corresponding to Giancarlo's voice are lower in frequency than those corresponding to Juan's voice;

that is, they are lower in hertz

Quick information:

Frequency has two distinctions and level for male and female. For male the voice frequency is 85 to 180 and a unit of hertz which is Hz and for the female is 165 to 255 hertz (Hz)

Trumpets, saxophone, trombone, flute, french horn  mostly in jazz or classic.  you can answer the rest thats on your own honestly 

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