How should the interface of the audio cable be dealt with after oxidation?

Oxidation of the audio cable interface can lead to poor contact, deteriorated sound quality or even no sound. It is necessary to clean it in time. The following are detailed processing methods for different interface types, along with operation steps and precautions:
I. Common Causes and Hazards of Oxidation
Reason
Environmental factors: Moist air causes metal contacts to rust (such as copper oxidizing into copper oxide), and salt in sweat accelerates corrosion (such as frequent contact of earphone plugs with the skin).
Usage habit: If the interface is not unplugged or plugged in for a long time, dust accumulates and forms a mixed film of “oxide layer + dirt”.
Material difference: Low-cost wires are coated with ordinary brass, which has weaker oxidation resistance than gold-plated/silver-plated materials.

Hazard
Sound quality issues: high-frequency loss (muffled sound), increased background noise, mono or intermittent disconnection.
Equipment damage: The oxide layer may cause abnormal current at the interface contact points, damaging the input ports of devices such as headphones and speakers.
Precautions
Prohibited tools: Steel wool balls, sandpaper and other rough items can scratch the coating and accelerate oxidation.
Drying treatment: After cleaning, it must be thoroughly air-dried (for at least 30 minutes) to prevent alcohol residue from corroding the contacts.
Iii. Cleaning Guidelines for Categorized Interfaces
1.3.5mm headphone/audio plug (TRS/TRRS)
Oxidation characteristics: The surface of the plug turns black, and there is noise or mono after being inserted into the device.
Operation steps:
Pre-cleaning: Use a toothpick to remove earwax and fibers from the gap of the plug (especially the groove near the root).
Alcohol wiping
Dip a cotton swab in a small amount of alcohol and wipe the metal ring of the plug clockwise (Figure 1), with a focus on cleaning the ring-shaped area in contact with the equipment.
If the contacts are severely oxidized, you can soak a cotton ball in alcohol and wrap it around the plug. Let it stand for 5 minutes to soften the oxide.
Eraser polishing: Gently rub the metal ring with an eraser (with moderate force to avoid damaging the coating) until the surface is bright (Figure 2).
Drying test: Use compressed air to blow away debris, insert the device to play audio, and rotate the plug to check if there is still poor contact.