You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Patulous Eustachian tube and explain in detail?
Patulous Eustachian tube (PET) is the name of a physical disorder where the Eustachian tube, which is normally closed, instead stays intermittently open.  When this occurs, the person experiences autophony, the hearing of self-generated sounds.  These sounds, such as ones own breathing, voice, and heartbeat, vibrate directly onto the ear drum and can create a "bucket on the head" effect. PET is a form of eustachian tube dysfunction (ETD), which is said to be present in about 1 percent of the general population.

Signs and symptoms
With patulous Eustachian tube, variations in upper airway pressure associated with respiration are transmitted to the middle ear through the Eustachian tube.  This causes an unpleasant fullness feeling in the middle ear and alters the auditory perception.  Complaints seem to include muffled hearing and autophony. In addition, patulous Eustachian tube generally feels dry with no clogged feeling or sinus pressure.
Patients hear their own voice or its echo from inside. They describe it as being amplified and unpleasant. Lying head down  may help since it increases venous blood pressure and congestion of the mucosa.

Causes
Patulous Eustachian tube is a physical disorder. The exact causes may vary depending on the person.  Weight loss is a commonly cited cause of the disorder due to the nature of the Eustachian tube itself and is associated with approximately one-third of reported cases. Fatty tissues hold the tube closed most of the time in healthy individuals.  When circumstances cause overall body fat to diminish, the tissue surrounding the Eustachian tube shrinks and this function is disrupted.Activities and substances which dehydrate the body have the same effect and are also possible causes of patulous Eustachian tube.  Examples are stimulants (including caffeine) and exercise.  Exercise may have a more short-term effect than caffeine or weight loss in this regard.
Pregnancy can also be a cause of patulous Eustachian tube due to the effects of pregnancy hormones on surface tension and mucus in the respiratory system.Granulomatosis with polyangiitis can also be a cause of this disorder. It is yet unknown why.
PET can occur as a result of liquid residue in the Eustachian tube, after suffering a middle ear infection (otitis media).

Radiation therapy
High levels of estrogen
Nasal decongestants
Stress
Sudden weight loss
Neurological disorders

Diagnosis
Upon examination of a suspected case of patulous Eustachian tube, a doctor can directly view the tympanic membrane with a light and observe that it vibrates with every breath taken by the patient.  A tympanogram may also help with the diagnosis.  Patulous Eustachian tube is likely if brisk inspiration causes a significant pressure shift.
Patulous Eustachian tube is frequently misdiagnosed as standard congestion due to the similarity in symptoms and rarity of the disorder.  Audiologists are more likely to recognize the disorder, usually with tympanometry or nasally delivered masking noise during a hearing assessment, which is highly sensitive to this condition.When misdiagnosis occurs, a decongestant medication is sometimes prescribed