Important disclaimer: deliberate interference with wireless communication may be illegal in your jurisdiction; the comments below are for recreational purposes and are not suggestions for implementation.
----------
Wireless microphones have been commonplace for a couple of decades and are seen in Kingdom Halls where they are used for a number of purposes including audience participation. There are several types of wireless microphones.
The least expensive type uses AM (amplitude modulation) to broadcast a low power (tens of milliwatts) analog signal with the frequency in the commercial audio (radio) band. These microphones are seen in toys for children. This type is easy to jam and is also easy to spoof (override with an unauthorized signal).
The most expensive type uses FM (frequency modulation) to broadcast a medium power (hundreds of milliwatts) digital signal with the frequency in a band especially allocated for such usage. The digital signal may use packets and various anti-jamming and other security measures. These microphones are seen in professional public performances. Jamming and spoofing ranges from being rather difficult to almost impossible.
The middle class of wireless microphones used FM to broadcast a low to medium power analog signal, either in the commercial FM radio band or a different band designated for such use. These are relatively easy to jam or spoof, particularly if the manufacturer is known and a second microphone of the same model can be obtained. Unlike AM receivers, most FM receivers will automatically select the strongest signal and reject, to some extent, weaker signals using the same frequency. Probably, most wireless microphones used in Kingdom Halls are of this type.
----------
Hypothetically, what types of, uh, "spiritual" speech would be, uh, most "illuminating" to the Kingdom Hall audience?
Suggestions:
1. (Trumpet fanfare) "This is Jehovah! Armageddon starts in fifteen minutes! I hope each of you put in ten hours last month!"
2. (Demonic laughter) "This is Satan! You have all been duped by my demons in Brooklyn! It's hell fire for all of you!"
3. (Loud static) "This is the demon Wormwood! We have control of your sound system!"
----------
Any other suggestions?