<Li> Congenital malformation of the ossicles . This can be an isolated phenomenon or can occur as part of a syndrome where development of the 1st and 2nd branchial arches is seen such as in Goldenhar syndrome, Treacher Collins syndrome, branchio - oto - renal syndrome etc . </Li> <Ul> <Li> Barotrauma unequal air pressures in the external and middle ear . This can temporarily occur, for example, by the environmental pressure changes as when shifting altitude, or inside a train going into a tunnel . It is managed by any of various methods of ear clearing manoeuvres to equalize the pressures, like swallowing, yawning, or the Valsalva manoeuvre . More severe barotrauma can lead to middle ear fluid or even permanent sensorineural hearing loss . </Li> </Ul> <Li> Barotrauma unequal air pressures in the external and middle ear . This can temporarily occur, for example, by the environmental pressure changes as when shifting altitude, or inside a train going into a tunnel . It is managed by any of various methods of ear clearing manoeuvres to equalize the pressures, like swallowing, yawning, or the Valsalva manoeuvre . More severe barotrauma can lead to middle ear fluid or even permanent sensorineural hearing loss . </Li> <P> Third window effect caused by: </P>

What is the cause of conductive hearing loss