Q#5 for Frank

I will now post my final question for Frank:

Frank, you said: "Paul is making it clear that the sign gifts only build one's self up while the prophecy/teaching gift edifies the whole church", and you used 1 Cor 14:4 to justify this point.

Yet, I raised the point that in the very next verse Paul provides an exception, "unless someone interprets, so that the church may be edified" (14:5). This would make it clear to me that a tongue does have power to edify, provided that it is properly used in conjunction with interpretation, so that the content of the tongue is understandable. Sign gifts, therefore, when used improperly perhaps only edify the individual, but when used properly do edify the church.

How do you respond to this objection?