One who speaks in a tongue should pray that HE may interpret

[tonychanyt]

Case #1 in 1 Corinthians 14:

13Therefore, one who speaks in a tongue should pray that he may interpret.

Who is he?

He is the speaker.

Case #2:

27 If any speak in a tongue, let there be only two or at most three, and each in turn, and let someone interpret. 28 But if there is no one to interpret, let each of them keep silent in church and speak to himself and to God.

Who is that someone?

That's someone who has heard the tongue speech.

Both cases are possible.