Pls give me brainliest!!!
I think they decrease echo and reduce noise, they do this by either absorbing vibrations or by scattering the sound so that echoes arrive at different times rather than reverberating as a standing wave. An echo is a reflection of a sound that arrives at the listener with a delay after the direct sound. The delay is usually proportional to the distance of the reflecting surface from the source and the listener.
Answer:
30 seconds
Explanation:
A = A02^-(t/hl)
--> ln(A/A0) = -(t/hl)ln2
solving for hl,
hl = -t x ln2 /ln(A/A0)
= -(60 min)xln2/ln(50/200)
= 0.5 min or 30 seconds
