Quiet/lost voice but no other symptoms - what to do?

[BigJ111]

During molt or when broody, my hens tend to make a quiet clucking sound.

They are not molting at the moment. But I'm not sure regarding being broody. The one who lost her voice tends to take her time in the nest box, definitely longer than the others but I wouldn't be able to tell if she's actually broody. Also because sh'es been like this from the beginning

 

[Tookie]

How is she?

 

[Jlw0903]

After 2weeks of apple cider vinegar or echinacea in the water, she's slowly getting her voice back. Still zero sign of anything else. She's been laying , eating and acting as normal. No obvious crop issue to me, no discharge from nose or eyes, no apparent breathing issue, nothing... i'm a bit puzzled to be honest. Was joking with my wife that maybe she was too chatty and lost her voice, but to be honest, at this point, apart from a simple irritated throat, I really can't figure out why she lost her voice. Now is way better, though not totally back to the regular volume yet.

I I have a duck that this has happened to several times already and I can't figure it out. None of the others seem to have issues. If you find out what it is please let me know!