Q: problems with the sound in the headphones when you press the keys iphone 5s

Greetings alexsuperpechen,

If you are getting distorted sound output through your headphones when you use your iPhone's keyboard, I would suggest that you troubleshoot using the steps in this article - 

If your headset isn't working - Apple Support

In particular the first troubleshooting paragraph -

You can fix most headset issues with a few steps. Try these first:

 

1. Make sure that the headset has a built-in microphone.
2. Unplug the headset and clear any debris from the headset jack. Then plug it back in.
3. Make sure the headset is plugged in all the way. If you’re using a case, remove it to make sure it’s not getting in the way.
4. Check the headset cable, connector, remote, and earbuds for damage. Make sure they’re not blocked or dirty.
5. Try using another headset. If the issue happens with the other headset, contact Apple Support for help. If the other headset works, contact the headset manufacturer.
6. Try using a different iOS device with your headset. If the issue happens with the other iOS device, contact the headset manufacturer. For Apple headsets, contact Apple support.

Thanks for using Apple Support Communities.

Be well,

Brett L