Why tenor?

Church service. You're preparing to play a hymn on the organ but you're sick of the usual SATB arrangement. You want some variety and color for at least some of the stanzas.

Sure, you could re-harmonize, change texture, put a hymn tune in another voice. But of all possible options, playing a tenor line one octave higher on a solo registration is one of the most colorful arrangements.

Why the tenor and not the alto, or the bass?

Because the tenor range happens to be similar to that of the soprano, if you move it up an octave. Of course, the alto played higher would be a possibility too, but this part usually lacks melodic interest and is here simply to fill in the harmony. Touching the bass is out of the question because the harmony would change.

So if you want to make your hymn playing more colorful, try this disposition:

The pedals take the bass, the left hand plays 3 upper parts in a closed position, and the right hand - the tenor line up an octave with a Trompette or a Cornette stop on a separate manual.

​This way you create a 5th voice - a nice descant. The impression will be like playing with another melodic instrument.