Whenever you stretch or relax a rubber band, it vibrates. The vibrations spread out in all directions, and if your ears are close enough, they can vibrate too, creating sound waves. These sound waves reach your brain and are processed by the nerves in your ears, which determine pitch, frequency, and where the sounds are coming from.
When you hear a sound that resembles the pulsing of a rubber band, it could be a sign of something called “eustachian tube dysfunction.” Each ear has a small tube that equalizes the air pressure on each side of your head by opening and closing. These tubes can become clogged with mucus when you have an upper respiratory infection like a cold, sinus infection, or allergy problems, or when you are standing up or lying down for too long.
You may also get a rubber-band sound when you have fluid or debris near your eardrum (tympanic membrane/TM). The spring-like sound can occur when you move around and the movement causes the fluid to change pressure. This can happen if you let water into your ear after swimming, or flying on an airplane, or even from yawning.
The best way to deal with a rubber-band sound is to flush out your earwax with a saline solution, which can be done by your doctor or you can use a bulb syringe and water kit at home. Avoid using cotton swabs, which can push the earwax deeper into your ear.