Answer:
Attempts to deepen your voice may cause damage to your vocal chords. You might lose it altogether.
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But if you really want to deepen your voice, there are several methods. The one I like is:
Once a day repeat "Ding Dong Bing Bong King Kong" while holding the "ng" sound for 7 seconds on each word. First do it with your natural voice, then try again with a slightly deeper voice. Don't do it anymore until the next day, or you could hurt your vocal cords. Continue to do this for a week, and then move onto saying it while tilting you head toward the ceiling. Once again, wait a week of practice before doing this, or you could hurt yourself. This stretches out the vocal cords, giving you a deeper voice. This method is used by a lot OS radio jockeys and some transvestites to get a deeper voice.