Using iPhone as a hearing aid?

Just a thought!
All smart phones have a microphone and a headphone socket so can one use the phone as an amplifier? Turn on the microphone, plug in the earphones and there you go??
I cannot find any evidence that this is possible but getting harder of hearing with age it would be a very useful application.
I'm using an iPhone SE.

Give it a miss.

Modern hearing aids can be made to slip inside the ear with no wires, external microphones etc.

I simply asked whether the iPhone CAN be used as an amplifier, not whether it will replace hearing aids, which I have.

One way to test whether it would work is to speak into the iPhone mic while wearing the earpods. (The mic is voice actuated.) What's wrong with wearing your hearing aids? Or are you like most folks who have them and don't wear them? (Just kidding you.)

I do wear them all the time when out walking so I can better hear the birds. As I said in my opening post, it was just a thought whether it were possible.
Thanks

The phones have a microphone and speakers and apps determine how they want to use it. Some apps only use the mic to record and save the data in a format that's portable. Others just use the speakers to play audio, and yet another class of apps will take mic input and do something to them and play them back (think Talking Tom).

So can an app take the mic input and just blindly pay it out of the speakers, absolutely. However, the mic on smartphones is very uniquely designed to pick up your voice from around the phone and send it off. They go through great lengths (through software or hardware manipulation) to drown out all background and far away noises to make the purpose of the mic (holding a phone call) as clear as possible.

Hearing aids on the other hands generally amplify all sounds and I'm sure there are ones that allow you to filter out certain bands to amplify spoken word as opposed to other noises, but that is very counter to what the hardware and software in a phone is designed to do.

I wear two hearing aids constantly and a hearing aid is completely different to an iPhone or any other phone.

Thank you Raz, most informative!

See here, http://appcrawlr.com/ios-apps/best-apps-hearing-aid,

iphone as hearing aid

An iphone with airpods has all it is needed to function as hearing aids, microphones, possibility to equalize and to boost the sounds and of course hearphones. all you need it is an app that work for that, i can suggest an app called "Fennex augmented hearing" that makes it all really easyly , just check on the appstore

Thanks for that, looks useful!