The first real setback for evp was the intervention of the spiritualists in the 1970`s who attacked the phenomena because it did not conform to what they were being told through their fake trance "mediums".
This was followed by the "spiritcom" debacle which was out garbage..it was 100% fraudulent and yet bizarrely..there are people today who still think it was real.
Amazing eh?
And the third modern setback for evp now days is the proliferation of people running around with devices like the ghostbox/franks box etc..which..to cut to the chase..have NOTHING to do with evp.
See the video below for a classic example..
This type of rubbish is perfect ammunition for the sceptics and a classic example of Pareidolia..how anyone could not find an "answer" in the tiny snippets from the radio stations is beyond me...its utter crap..
Interesting take on this garbage here