I didn’t want this answer left unanswered, but my answer is one not researched, just what I think I know to be true. It is late or else I would double check before answering.
What I think is the case is that we don’t necessarily believe that the saints in Paradise literally hear us, but that it is possible for them to hear our petition. This could be literally, or it could be through the angels “their name means actually who they are ‘Messengers’” So the same should be valid for the saints in Purgatory (I called them saints because their destination is heaven) If in their purging they cannot hear us, it is possible, if the Lord permits, for them to hear us through the Angels. Also, we don’t know who might be in Purgatory, actually we don’t even know for sure if it is a space in time, it could be a state, but not a place, it could be outside of time, or in time…but that is a different subject.
So, if we pray (speak) to some of our loved ones who ended their time on earth, we have no way in knowing weather they are in Paradise or in Purgatory. So in our honesty, the Lord will allow all that is His will.
Hope this helps, I sometimes ramble…
Peace of the Christ be with you,
Luigi