“…A total of 15 studies used headphones for testing [10,21,23,38,41-47,49,50,52,54], 9 studies used earphones for the examination [22,29,36,37,39,40,48,53,55], and 1 study did not mention the equipment used[51]. In all, 6 studies conducted the examination in a soundproof booth[10,[49][50][51]53,55], 18 studies did not use a soundproof booth to conduct the examination[21][22][23]29,[36][37][38][39][40][41][42][43][44][45][46][47]52,54]…”