If the noise is lower, the AC service may be the cause. Magnetic fields from transformers can cause humming. Mains transformers typically cause an AC magnetic field around them. This magnetic field can be copled to wiring, electronics or signal transformers and cause humming.
Baby oil benefits: ear. Mineral or baby oil is good from treating common ear problems, such as wax build-up. For those that are hard of hearing, we recommend using a few drops of heated baby oil before going to your ear specialist. Then pour the drops in your ear, keeping your head cocked. Hold for a few minutes.
Being in such a delicate area, perhaps diluting the oil with almond oil or jojoba oil would be wise. Just 2 to 3 drops of almond oil per drop of helichrysum would probably do it. The oil will still penetrate. The blend Gentle Baby is used by many mothers after giving birth for reducing scars and stretch marks.