Mmm, I don't know about this one. I think he used his voice in that moment because the moment was so intense and emotional, and it was the best way he could think of to get Bay to 100% understand him and know that he meant everything he just said/signed. I can see him speaking again when saying ILY to her, or something as emotional as the last episode, but I don't feel like he would speak to her, with his voice, daily. I feel like he will try had to break out of his bubble and vocally speak to her, but if there is no need in that moment and she can understand his signing, he won't. Him using his voice is a struggle for him, and the writers made a point of letting us know that the last time he spoke vocally was EIGHT years ago - thats a long time. He also told Bay that he does not need to use his voice, so I don't see his opinion changing too quickly. He spoke to her with his voice in a moment of raw emotion...unless a moment carrying the same intensity happens again, I don't see him using his voice too much and I doubt Bay would expect him to.
Last thing, I think when he does speak again, it will once again be to Bay. I think this will deapen their connection and be something just between the two of them. At least I hope so.
And like someone said, I hope Bay doesn't let Daphne in on it either.
I like that they have these little secrets that are reserved just for them...it shows they trust each other. Bay trusts Em enough to show him her art and make him her partner in crime, he trusts her enough to speak, and lets not forget about the scarf...only they will ever know what the scarf really is
