Bluetooth and the 2.4 GHz ISM band is not electricity and is highly resilient to moderate noise over short distances. Problems are usually caused by hardware related issues.

A man named Michel Thomas created a series of audio lessons to teach a number of languages, including German. He does it in a simulated classroom type of environment where one “student” makes common mistakes and he corrects them, so you get to hear someone else make the mistake first.

He also teaches you the necessary words to enable you to start understanding others speaking he language quickly. I found combining this with Duolingo and the super cheesy Extr@s TV series (once you have the basics) allowed me to go from 0 to speaking to people within 6 weeks and understanding 95% within 6 months.

I learnt Spanish and German from his audiobooks. They are worth the money if you can afford it and/or cannot pirate it.