Stationary Wave Questions: Can Open Tubes Produce Them?

[momomo_mo]

Questions again!
AS I know stationary can be produced by the reflection of waves in a closed tube.But how can stationary still be produced in an open tube??


Thanks for your help

 

[Hootenanny]

Think in terms of air pressure. What is the air pressure likely to be at the open ends of the tube? What is it likely to be at the centre of the tube?