This suggests a possible meta-study on intelligibility of technical works by native and non-native speakers. A technical paper in phonology might be unintelligible because of the linguistic structure of the article, or because of the subject matter. The same is true in speech and hearing science, and various other areas. Fortunately, SPHS and phonetics papers tend to follow a formula for presentation, and that means that in section 1 you will know the point of the paper. In section one there is a fair amount of talk that justifies expectations, which from a practical perspective you don't care about (not initially).
There are some language-related conventions that can get in the way, for example the fact that speakers are called "talkers" (I suppose they would say, looking at a linguistics article, that we call talkers "speakers"). This is disciplinary jargon, not an ESL matter. Same with hyper- and hypo-speech. Everybody in the discipline (that discipline) knows what hyper-speech is, at least I think I have heard that expression. You may have to read the article they refer to in order to understand that expression. The main point that you can extract from this section is that physical outputs are partially shaped by "mental context" (various social and communicative factors, not just a person's physiology).
They say what experiments 1 and 2 are intended to do, so read that part over and over. There is nothing at all quantitative in the article in section 1. If you do not understand section 1 (I will admit that I do not truly understand section 1), you won't understand the article. This is not about understanding linguistics articles in general, this is about understanding a specific article.