بسم الله الرحمن الرحيم
(Fatwa: 451/367/D=6/1438)
The detail of ‘echo’ which you provided suggests that it should not be used in salah, it shall make the salah makrooh as it creates the eco and causes disturbance as well. It should be avoided in salah.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
