TTS for short, this is an upward shift in the threshold of human hearing. It is usually caused by being subjected to a loud sound. The human auditory mechanism is remarkably tolerant of abuse, and it has several ways of protecting itself from damage when exposed to very loud sounds. One of these is to reduce its sensitivity, causing the hearing threshold to shift upward. As the name implies it is a temporary condition, but continual exposure to loud sound will cause it to become permanent. This is known as permanent hearing loss. You only get one set of ears for life, so take care of them. Make it your New Year’s resolution.