Ear speaker too low sound

Ah, you are referring to the "receiver." Sorry, I never heard it called an "ear speaker," but that certainly makes sense.

Regardless, the first support article offers tips on how to try to resolve volume issues.

Here are a few more you can try:

• How Do You Change the Ear Volume for Phone Calls on an iPhone? - Chron
• How to fix low or increase call volume in iPHone 6, 6 plus, 7, 7 Plus - How To iSolve <= You didn't provide which exact iPhone model you have, but it looks like it could one of these from the image.

Finally, if none of those articles help, here are a few other things you can try:

1. Thoroughly clean the receiver.
2. Perform a "forced" restart on your phone. Ref: Force restart iPhone - Apple Support
3. Make a Genius Bar appointment at your local Apple Store or Apple Authorized Service Provider to have them take a look and provide you with your options.

See if the following support article can help:

• If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support

By "ear speaker" are you referring to the Apple wired EarPods that come with the phone? If so, have you tried simply cleaning them?

Ref: How to clean your AirPods, AirPods Pro, AirPods Max, and EarPods - Apple Support