Inflammation, infection or irritation of the larynx and the vocal chords.

Symptoms : Pain, itching, irritation and inflammation which doesn't allow one to speak naturally.

Causes :

• Smoking and drinking alcohol
• Too much speaking
• Singing or shouting excessively
• It is also caused by an infection due to bacteria in the air that is inhaled, or by contact with infected saliva from another person.

Low activity of the thyroid

Hypothyroidism is a disease of the thyroid gland which is characterized by the low production of hormones (this phenomenon is the opposite of hyperthyroidism). The general metabolism of the cells in the body is affected by this disorder, including the brain cells. That is why the intellectual abilities of the person are affected and in many cases, especially children, it is believed that there is mental retardation.

Symptoms :

• Fatigue
• A lack of strength
• A lack of concentration
• Sensitivity to cold
• Loss of appetite
• Dry skin and hair
• Blindness during night hours
• Impotence in the man
• In women, the mensuration is excessive and irregular

The main causes are : iodine deficiency or heredity.

Increase in activity of the thyroid. Hyperthyroidism is characterized by the over-production of hormones by the thyroid.

Symptoms :

• Nervousness
• Fatigue
• Weakness
• Weight Loss
• Insomnia
• Mood swings
• Trembling hands
• Excessive perspiration
• Intolerance to heat
• Fast pulse
• Irritability

Causes : Heredity is the main cause but there are other unknown factors also which are under research.