I have heard many native speakers in the United states answer with a brief and cold "aha" when someone says "thank you". Is it really appropriate to answer like that? I myself feel offended when I receive such a response from a teacher or someone I don't know.
I think what you are actually hearing is a short, simple "uh-huh", which is intended as an acknowledgement that they have received your thanks and consider the exchange complete. It is not intended to be rude; in fact, ignoring someone who says "thanks" is much ruder. It's very informal, and is probably mostly used when whatever answer they gave that prompted you to thank them was a small, barely noteworthy thing.
Other utterances that you may hear include:
- you bet
- no prob
- mm-hmm (or even just mmm)
- (a head nod)
Edited [The original post asked for ah, not aha.]
To a peer or a social inferior, aha may indeed be appropriate in casual situations— in fact, a mere mmm or wave of the hand would be sufficient. It is an acknowledgement of the thanks, but simultaneously a dismissal of it as if it were unnecessary.
I almost never hear you're welcome, the conventional response, except in more formal situations or where the respondent is expressing an extra level of deference (for instance, if I thank a waitress for her attentive service).
I don't know any Americans who would say ah (/ä/), but I know some who might dismiss it with a mmm or uh-huh or eh (/e/), accompanied by a nod or shrug or wave of the hand, in casual exchanges with a peer.
There are numerous ways an English speaker may reply to a "thank-you" and the intent is almost never to offend; however, due to cultural differences, it seems that responses like eh or no problem seem to offend some.
The eh-er is trying to express that whatever it is that inspired the expression of thanks was a small matter, and that the thankful person should therefore not feel that he or she has any obligations on account of it, thus don't worry about it, it's no big [deal], no worries, no bother, not at all, don't mention it, and so on.
I tell you that aha is much more respectable than no response at all , it is American normal way of responding to thank you , I am myself not originally American , I notice that mostly non-Americans are offended by this normal aha , I had a non-American friend who was going really crazy if americans said aha after he said thanks ...I am sure if he had a compilation video of how americans usually respond to thank you , he would be no more mad at hearing aha