Please help, really need advice - Your interpretation?

Hey everyone – I would be extremely grateful for any help on this particular example please.

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The scenario:

You and your friend have just had a Physics lecture. It was the first time you had been taught by this particular teacher as your old teacher has left.

You say to your friend: “What do you think?”

Your friend replies:

Either 1): “We learnt a lot more in that lecture. I definitely know about the distance-time graphs now, hehe.”

Or 2): “We learnt a lot less in that lecture. I definitely know about the distance-time graphs now, hehe.”

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You did not hear/understand the first part of the reply correctly (highlighted in orange). You know your friend said either “We learnt a lot more...” or “We learnt a lot less...”. You then correctly hear your friend say “I definitely know about the distance-time graphs now, hehe.”

Do you think your friend meant (without asking them to repeat themselves) either version 1 (positive opinion of new teachers lecture) or version 2 (negative opinion of new teachers lecture)? Or do you think it is impossible to tell without hearing the speaker’s tone of voice to detect any sarcasm or a displeased attitude (E.g. the way “definitely” is pronounced/ the type of laugh ) and any other indicators to suggest you friend is not impressed with the new teachers lesson (E.g. Rolling eyes, sighing, etc.)?

In my opinion the laugh ‘hehe’ may or may not be an indicator of sarcasm or a displeased attitude. Version 1 makes sense and sounds positive and genuine with or without a laugh at the end of it (I guess it depends on the type/tone of the laugh to say if it is meant in a respectful or disrespectful manner) – would anyone agree?

To me saying I definitely know about something is a positive comment but I guess it could be meant in a negative and disrespectful way if for example the student feels “distance-time graphs” were too basic at their particular level of education. If the student feels this way (teaching too basic) do you think he/she would say the phrase: “I definitely know about the distance-time graphs now” in a different way to how they would say it if they were pleased by the fact they had definitely understood the graphs?

Thanks in advanced for any opinions, I very much appreciate your time.

Rich