Variation

Where there is agreement.....
call is described as being softer or quieter than the cock call
it is a simple call
the same simple call is repeated 2 to 4 times
hen calls are much less frequent than cock calls
it is not shrill

But what is the hen call?
It might not be a single call, it could be several calls
Variations could be caused by age, environment, paired or unpaired etc.

Below is one call which turned out to be a hen. It is from a young bird which might explain why it is slow.

a young hen

So how is it done?
given the difficulty of knowing exactly what hens sound like, and as they call less frequently...

in a long cage (6') containing 3 to 5 birds listen for the unambiguous, pure cock call - call 2
catch that bird, put on a (blue) ring and move him to a cage elsewhere

wait up to a week for another cock to gain confidence to announce himself and repeat, ring & move elsewhere
(it often only takes hours or a day maximum)
if get muddled calls, change the composition in the cage of 3 to 5 birds

at the end you have got only hens..
if unlucky you could end  up with the odd timid or shy cock but that rarely happens

then - pair confirmed cocks and supposed hens - perhaps let each hen choose from a couple of cocks - but watch for fighting

an important and verified observation from Alice Mourisot
birds as young as 6 weeks start teaching themselves to call
this is probably one of the easiest times to determine their gender as they practice incessantly

So that's the calls - how about - housing