Answer
(Fatwa: 341/321=B/1430)
If the machine is on and the chickens are slaughtered while a person is reciting bismillah or a recorder is played, then this slaughtering is not valid and the meat will not be halal. Rather, the slaughtering will be valid only when a person recites bismillah and slaughters the animal. Only by reciting bismillah on first chicken, the other ones will not be halal, it is necessary to recite bismillah while slaughtering every chicken.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband