Immediate effects of semi-occluded vocal tract exercises in low and high voices: a self-perception study.

The study showed that the effects of these exercises are different and should be suited for each type of voice, such as the latex tube, which was the most preferred by low voice participants and also rated as less beneficial by high voice participants, and the high-resistance straw, which was the most preferred by the high voice participants and also rated as less beneficial by low voice participants.