I subvocalize parts of words and parts of sentences. Lumping everything from this strategy to hearing complete words and sentences under "subvocalization" might be a bit misleading. I stop noticing it when in deep concentration, but as you said this doesn't mean it's not happening. You stop noticing all sorts of stuff that's definitely happening when you concentrate, that's the point. Switching language from Finnish to English doesn't seem to have any effect.