Written It depends on how loud the air conditioner is... Exposure to noises that are too loud or loud sounds that last a long time will damage the sensitive structures in your inner ear causing noise-induced hearing loss, also known as industrial deafness. The sounds damage the microscopic hair cells inside your ear. The cells are responsible for converting sound energy into electrical signals that travel to the brain. Once the cells have been damaged or broken they will not grow back, resulting in hearing loss.Sounds are measured in decibels (dB). An average person can hear sounds down to 0 dB which would be something very quiet like the rustling of leaves. A quiet library measures about 30 dB and a normal conversation occurs at 60 dB. When a sound reaches 85 dB it can start harming your hearing.If the air conditioners noise exceeds 85dB it will begin to damage your hearing after 8hrs of collective exposure. Common Noises Can Cause Permanent Hearing LossHow long does my aircon unit need to be upright before use?