Spectrographic analysis of Egyptian Cairene /r/: is it a trill or a tap?

The /r/ phoneme is variable in manner and place of articulation, and difficult to correct worldwide. Variability could exist within the same language. The objective of this study was to determine whether Egyptian Cairene /r/ was a trill or a tap and, if both forms were present, whether they were affected by word position or adjacent vowels/consonants.