Air hole making wheezing sound

[Erik66]

Hi,

My concertina is making a whistling/wheezing sound when I use the air button.
It is a relatively small hole with sharp edges.
Both on the push and the pull.

Will this be less if I round off the sharp edge of this hole?
Is there another way to make this more silent?

[alex_holden]

Rounding the edges of the hole should help slightly, but enlarging it and fitting a bigger pad would be a better option if there is room to do so.