'He had left his room impulsively in the belief something was wrong; Now it seems to him he might merely be trespassing on the privacy of some member of the household.' - the word 'impulsively' shows that he felt Inclined to act on impulse rather than thought and now he thinks that he shouldn't have , However i get the impression that by Stephen saying that he 'might merely be trespassing'' makes me think that he believes that Madame Azaire has been hit by her husband more than once. Also, I think that by the last sentence that he thinks it is non of his business to find out whats going on as it's between Madame Azaire and Azaire, He is also only a guest at the house so he probably believes it would be disrespectful to be sneaking around and poking your nose in other peoples business when they've had the decency to let you stay there.
'He could feel the swell of his heart against his chest and a light pulse in the flesh of his neck' - The reason for this could be because he's moved closer to the door and anyone could potentially find him snooping around so he is more aware of things and is therefor more aware of his own pulse, Also in stressful situations your blood pulse is faster and potentially he could feel angry about the situation so his blood pulse has risen to the point it's noticeable to himself.
'He heard a woman's voice, Cool and low, though made intense by desperation' - Madame Azaire is most likley to be pleading with her husband and trying to stay calm by talking 'Cool and low', It could be so that he will calm down, Also the fact that her voice was made by 'Intense and desperation' shows that she is trying her hardest to stop him hitting her again.
Stephen could hear distinguish the words 'Rene' and later 'I implore you' - To implore someone is to beg them to do/ stop doing something in an emotional/ Forceful way, The likelihood is Madame Azaire is again begging her husband to stop, This also gives me the impression that in the household that Azaire is much higher up than her and she is most likely to do what he says and avoid making him mad.
'Stephen moved forward along the corridor, his hands no longer raised cautiously in front of him but tensed into fists by his ribs' -Clearly Stephen is angry by the fact he's 'Tensed his fists' and forgotten completely about the fact earlier on he didn't dare move any further towards the door for fear of getting caught but now hes forgotten about that.
'Stephen turned and ran for cover of the passageway, Knowing he had advanced beyond the limit he had set himself.' - Now he's realized that he has gone further towards the door than he should have and is now thinking about running away rather than getting angry and punching Azaire.
'He stood in the middle of the room, Listening.'- Because he's had a lucky escape he's basically in shock and doesn't really know what to do, Also he's most likely thinking about what he's just overheard.
'It made brief comments on the character of Bernard and his wife, under heavy disguise, and gave his impressions of Azaire and the two children. He saw, With some surprise, that what had struck him most he had not written about at all'
- From this i get the impression that Stephen originally thought that people we're completely different to what they now seem like 'Under heavy disguise' and the last part of the sentence is basically saying that what has shocked him most was not about what he had written, it's what had just happened.
