Tinnitus in the left ear may be caused by noise, psychological stress, ear diseases and systemic diseases. 1. Noise: Long-term stimulation by noise may cause damage to the hair cells of the inner ear, thus causing tinnitus in the left ear. 2. Psychological stress: recent emotional instability, excessive fatigue, lack of sleep and insomnia, etc. may also trigger tinnitus in the left ear. 3. Ear diseases: such as otitis externa, foreign bodies, acute and chronic inflammation of the middle ear, tympanic membrane perforation, etc. can cause tinnitus in the left ear. 4. Systemic diseases: neurological disorders, lack of blood supply to the brain, blood pressure and other diseases, with age, the decline of the auditory nervous system can lead to tinnitus in the left ear. Patients with symptoms of tinnitus in the left ear should go to the hospital in a timely manner, under the guidance of the doctor to determine the cause of the disease and then treatment.