Native speakers can speak very fast. That said, I find it hard to believe that you cannot hear the difference between "a" and "the'.
Interested in Language
In a dictation practice to the sound of an English narration, I often make a mistake in telling articles "a" or "the". Can most native English speaker tell the difference of those two words only by their sounds? They are usually uttered weakly and faintly in natural conversations. Contexts might be good help in many cases in real life situations. However, using CDs, I often find it difficult to tell them because a sentence in a textbook is generally too short to guess its context. Does somebody give me good advice?
I am not a teacher.
I must admit that it surprised me too, but after further thought, the unstressed articles (which pose no problem at all for native speakers) could sound similar to the untrained ear.
Having said that, it would have to be a very lazy pronunciation of "the", but it just comes down to a slight movement of the tongue.
It's true. It doesn't always happen, but during my practice I make mistakes at least one out of five or six times. Probably, one of the reasons is that, consciously or unconsciously, my attention is drawn to other more conspicuous words than those articles. The level of difficulty also depends on a speaker or the speed of speech. However, in the worst cases, even though I listened to the same recording more than five times, I made a mistake.
****Not a teacher of English language ****
Mogu, if you have the audio file of the material, perhaps you can try playing it with VLC player (free sofware) at a slower speed. In VLC you can also put a particular segment of the file in a loop ( so that you can listen to it again and again, without having to 'rewind' or go back). You can do this (loop a segment) on the fly - ie you can do this while the audio is playing. You don't have to stop and start. These two features of VLC (changing speed without change in pitch, and ability to loop on the fly) are very useful for language learners.
If that doesn't help, or if you want to try another method just for fun, you can open the audio file in a (free) software called Audacity. You can see the sound represented with graph so that it is easy to see the difference between two sounds.