Two loudspeakers, a and b, are driven by the same amplifierand
emit sinusoidal waves in phase. the frequency emitted byeach
speaker is 172 hz. you are 8.00 m from a. what isthe closest you
can be to b and be at a point of destructiveinterference.

1 m

Explanation:

given,

frequency emitted by the speaker,

f = 172  Hz

speed of sound,v = 344 m/s

distance of Point A = 8 m

   λ = 2 m

For destructive interference

the closest you  can be to B and be at a point of destructive interference  

 = r_a - r_b

 = 8 - 7

  = 1 m

double the distance = divide strength by 4

he made 11 calls in one day