But presently the phrases became distinct again whether because the other two had 51 insensibly raised their voices, or because Tommy's ears were getting more attuned, he could not tell.
Tommy could not understand the phrases at all anymore.  
mnli hypothesis: Tommy could not understand the phrases at all anymore.   premise: But presently the phrases became distinct again whether because the other two had 51 insensibly raised their voices, or because Tommy's ears were getting more attuned, he could not tell.