The causes of throbbing sound in the left ear may include mental stress, hypertension and secretory otitis media. 1. Mental stress: due to the patient’s mental tension, excessive fatigue, etc. will cause nervous system disorders, appearing in the ear blood vessel flow rate and flow changes, induced by the beating sound in the left ear. 2. Hypertension: If the patient has high blood pressure, vascular pressure increases when the blood pressure rises, and vascular throbbing tinnitus may occur. 3. Secretory otitis media: the lesion may cause middle ear effusion, and then the middle ear cavity vascular pulsation sound conduction to the inner ear, manifested as the phenomenon of throbbing sound in the left ear. If the symptoms of tinnitus in the left ear persist, it is recommended to consult a doctor for a clear diagnosis to avoid delaying the condition.