Church Hearing

You have many options. I'll try my best to list some for you.

• An iPhone and MFi compatible hearing aids where the hearing aids can be connected to an iPhone. You can put the iPhone into "Live Listen" mode and place the iPhone near a speaker and the audio will be transmitted directly to the user's hearing aids. There is virtually no delay in audio. This can only be used with one pair of hearing aids so you would need an iPhone for every user.
• You can setup a device or computer to stream the audio over the internet and each user that wants to listen to that stream can open the website on their phone and listen in. This is a simple and inexpensive approach but there may be a delay in the audio that might not be as pleasant.
• Some churches like mine provide wireless receivers and headphones. They are in a basket near the entrance way and can be picked up on the way in. Headphones over hearing aids are not the most comfortable thing in the world and might cause interference with the hearing aids but can usually be reasonably managed.

There are other products available for classrooms and lecture halls, these systems can be pricey and proprietary. I won't try to dive into that just yet.