“…Although some systematic reviews and further single studies noted for HNR [ 6 , 8 , 17 , 23 , 24 , 25 ], Jitter [ 26 ], Shimmer [ 24 , 26 ], CPPS [ 18 , 21 ], SPL [ 6 , 8 , 18 , 26 ], and AVQI [ 21 ] significantly effects by RPMs, the present evaluation of this meta-analysis did not support these findings using the software Praat for the signal processing of the included acoustic measures. Further studies that were not included in the present meta-analysis (based on different signal processing methods of the acoustic parameters or other mask types) also concluded that for the same acoustic measures for vocally healthy and voice-disordered individuals, no significant differences between wearing a RPM or not [ 27 , 28 , 29 ]. Moreover, it must be taken into account that voice physiology and voice characteristics may differ between different speakers and between single or multiple voice recordings for consistency of sound measurements [ 30 , 31 ].…”