Hello,
Sorry, you can’t use scores for anything except relative comparison within the same session while it is in similar environmental circumstances. They can’t be used to evaluate across sessions or across speakers since they are sensitive to many factors including distance, noise, accent, nearness of the speaking frequency to the mean that was used in the model, the device, and the vocabulary size and complexity. You will end up with misleading data if you try to use scores to isolate only one of those factors.