There are several reasons for dizziness when speaking loudly: 1. Consider that the person is using more force when speaking loudly, and the lung capacity is larger, which can affect the body’s breathing and thus cause a lack of oxygen in the body. As a result of the symptoms of lack of oxygen in the lungs, the blood in the brain can show a lack of oxygen, which can still be manifested as dizziness, and in severe cases, headaches can occur after the patient speaks loudly for a long time. 2, dizziness from speaking loudly is still considered to be due to the increase in negative pressure when a person speaks loudly, which will also have a certain effect on the intracranial pressure. The change in intracranial pressure can lead to abnormal cerebral blood flow, and the patient can also experience dizziness. 3. Some hypertensive patients can have elevated blood pressure after speaking loudly or due to emotional stress. After the increase in blood pressure, the patient may experience dizziness, and in severe cases, dizziness and headache.