Dry rales are a long-lasting, musical breath sounds with a high pitch and a fundamental frequency of about 300-500 Hz. They are long-lasting and can be heard during inspiration and expiration, but are more pronounced during expiration, and their intensity and nature are easily altered, and their location is easily changed, so that their number can increase or decrease in an instant. The dry rales that occur in the airways above the main bronchial tubes can sometimes be heard without a stethoscope and are called stridor. Treatment and prevention of dry rales 1. Adopt good living habits and do not smoke. 2. Maintain a good state of mind and stable emotions, and have a healthy diet. Eat plenty of fruits and vegetables to improve your immune system. 3, must work in the heavy fumes of people try to protect themselves such as wearing a mask regularly go out to breathe some fresh air at least once a year to do a checkup. 4, away from smoke, alcohol, drugs, radiation, pesticides, pesticides, noise, volatile harmful gases, toxic heavy metals and so on.