Muffled hearing in one ear can have many different causes, some of which are very minor and you can attempt to resolve yourself. Listed below are multiple steps that you can follow which may resolve your muffled hearing in one ear.
Check to make sure that you haven't got water inside your ear. This can happen after swimming, taking a shower, or any type of activity that involves a large volume of water near your ear. If you think this could be the case you can try gently tipping your ear towards your shoulder on the affected side to let the water drain out.
Try cleaning the wax buildup out of your ears using a q-tip. If you don't have a large amount of wax built up in your ears cleaning them out with a q-tip may reduce your muffled hearing. If you decide to try this method, make sure that your q-tips are sterile and that you are very gentle with them around and inside your ear.
Attempt to remove the wax buildup in your ear with wax softening drops and water irrigation. Most pharmacies and drug stores sell kits that contain ear drops to soften the wax within your ear and a bulb that holds water for the irrigation process. The kits usually come with detailed instructions and cost less than ten dollars.
Decrease the muscle tension around your ear. There are numerous muscles that surround your ear and neck and can affect the way that you hear when they are too tense. Try taking a warm bath or lying down to rest your neck muscles.
Don't let muffled hearing go untreated. Some causes of muffled hearing in one ear can be serious, and it's very important to be seen by a physician if your muffled hearing doesn't clear up right away or is associated with any measure of pain.