Is there a standard way to translate phrases like "a _ used for _".

Example: I'm trying to define 'Ohr' in German as "organ used for hearing". Based on what I've read, I've come up with a few possibilities, but I'm not sure which to prefer:

>1. Organ für Gehör benutzt
>
>2. Organ für das Gehör benutzt
>
>4. Organ zum Gehör benutzt
>
>5. Organ benutzt zu hören

Are any of the above correct "_ used for _" translations? Also, does a construction like that sound weird in German?