Anybody else's iPhone 11 can barely hear people talking over the line?

During a live call use the Vol Up button.

If that fails to increase the volume then arrange a repair

https://support.apple.com/iphone/repair/service

or: contact Apple Support 

Anything other than Screen or Battery may be a replacement phone and the price is in the article.

You can see additional service information within the following article:

Prepare your iPhone for packing and shipping

see also How do iPhone volume controls work?

Check your warranty options if you are in UK

https://www.apple.com/uk/legal/statutory-warranty/uk/

"Under consumer laws in the UK, consumers are entitled to a free of charge repair and (depending on the circumstances) may be entitled to a replacement, discount or refund by the seller, of defective goods or goods which do not conform with the contract of sale. For goods purchased in England or Wales, these rights expire six years from delivery of the goods and for goods purchased in Scotland, these rights expire five years from delivery of the goods."

Let us know when they broadcast it.