I recently learned that a nasheed is haram to listen to if it has sound effects which sound like musical instruments even if they are 'vocals only' (source). However, I don't have much idea about musical instruments.
There are a number of nasheeds by Maher Zain which are labelled as "Vocals only - No Music", and what I want to know is whether these nasheeds would fall under the prohibition in this fatwa (i.e. do any of the recorded vocals count as "effects which sound like musical instruments"?).
I am not interested in personal opinions and especially not in arguing about the validity of the fatwa itself; I expect answers to be backed by evidences, and these evidences must be compatible with the Salafi methodology used by IslamQA (the source of the fatwa itself).