ある as a pre-noun adjectival is used to mean "one" or "a certain," in common constructions such as ある日.
In this case, ある is clearly bringing some "baggage" with it in the form of:
(Where the の is converted from が). So you can be certain that ある is acting as the verb in a phrase modifying the noun 声.
Having said that, I don't think there's any ...