Hi GinaJM55,
Welcome to the Apple (user-to-user) Community!
Re: "Switch off speaker when streaming to hearing aids" : "what do I have to do to mute the iPad speaker when I’m streaming direct to me hearing aids?"
Wondering if updating your iPad to the newest compatible iPad OS version may help: Eg: You could check in Settings > General > Software updates
If an update is available, it is wise to back up your iPad before updating.
If no updates are available: You could try restarting your iPad (deletes temporary files, re-establishes connections, may update recent setting changes, and often restores order if something is not working as expected)
If needed: See how to: Restart your iPad - Apple Support
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More info: The linked article below says:
"Bridge" accessories for audio streaming
Some hearing aid manufacturers offer special "bridge" hearing aid accessories that receive audio through bluetooth from the iPhone and retransmit that audio using proprietary wireless audio-streaming technologies built in to some hearing aids. Check with your audiologist or hearing aid manufacturer for more information.
Info: comes from:
About Hearing Aid Compatibility (HAC) requirements for iPhone - Apple Support
All the best :-)