Hi! I am new to the site and I was looking for some help finding a device. Does anyone know if there is a device (possibly with a microphone) that is used to change the frequency of your voice to a desired range? Also something that would enable you to hear certain frequencies and not others by adjusting the frequency range the device picks up? This could possibly be 2 different devices but would be great if there is something that does both! Any help is greatly appreciated, thank you in advance!