Tympanic membrane retraction tensa. Tympanic membrane retraction is fairly common and has been observed in one quarter of a population of British school children. Retraction of both eardrums is less common than having a retraction in just one ear. It is more common in children with cleft palate. Tympanic membrane retraction also occurs in adults. Attempts have been made to categorise the extent of tympanic membrane retraction though the validity of these classifications is limited. The majority of tympanic membrane retractions do not cause any symptoms. Some cause hearing loss by restricting sound-induced vibrations of the eardrum. Permanent conductive hearing loss can be
Membrane operating conditions, cost and performance, it should prevented, and if necessary, removed. Optimizing the operation conditions is important to prevent fouling. However, if fouling has already taken place, it should be removed by using physical or chemical cleaning. Physical cleaning techniques for membrane include membrane relaxation and membrane backwashing. Chemical cleaning. Relaxation and backwashing effectiveness will decrease with operation time as more irreversible fouling accumulates on the membrane surface. Therefore, besides the physical cleaning, chemical cleaning may also be recommended. They include: Optimizing the operation condition. Several mechanisms can be carried out to optimize the operation conditions of the membrane