pronunciation of "octave"

[arpiruk]

Dear All,

 

I am wondering about two questions.

First, how should we pronounce the word “octave”

My German colleague always pronounce  it  as  oct-taaf ,  like staff.

Some others argue that it should be oct-teyv  like slave.

 

Second, how was the creator name it “octave” what are the reasons behind ?

 

 

Sincerely,

 

Arpiruk Hokpunna