I asked a question just now.
Could someone help to listen if the speaker is saying ...
Is this expression "Could someone help to listen ..." polite and clear?
Although a reader will probably be able to understand what you mean, the phrase "help to listen" is not correct and the sentence as a whole would not be expressed this way by a native speaker.
There are two elements to your request. First, you are asking for help. Second, you are explaining what specific help you need.
Further, if you wish to sound polite, you ought:
Taking account of the suggestions above, some better ways to express your request would be as follows.
"Could someone please help me? I would like you to listen to this recording and tell me what the speaker is saying."
"Could someone please help me by listening to this speaker and telling me what you think she is saying?"
"I would appreciate some help in understanding what the speaker is saying."
I hope this helps. If you express the question more clearly, then your responses will likely be more positive.