$6.)[15$ pts$.$ total$]$ A new machine $($M$)$ with a sound power level of $98\mathrm{.}5dB$ is being installed in a

factory workroom that is $40ft$ wide, $75ft$ long, and $12ft$ high. The workroom has an average

sound absorption coefficient $$ of $0\mathrm{.}03.$ The machine will be placed at one end of the room

on the floor and up against a wall as shown in the floor plan below. An operator work station

$($WS$)$ is initially placed $10ft$ from the machine.

ASSUME THE PRODUCED NOISE IS MONOTONIC AT $1,000Hz$ and THE MACHINE HAS

NO INTERNAL DIRECTIVITY.

a$)[5$ points$]$ Predict the sound pressure level at the work station with the machine

operating. Determine whether the sound pressure level at the workstation is in$..$

compliance with the ACGIH TLV $($for $8$ hours exposure$)$ and if not, calculate the

allowable exposure time according to the TLV$.$

Now for each of the exposure control scenarios in parts b$)$ and c$),(1)$ recalculate the

exposure level at the workstation, $(2)$ evaluate its compliance with the TLV$,$ and $(3)$

determine allowable exposure time:

b$)[5$ points$]$ The workstation is moved close to the wall opposite the machine, $70$ feet

away.

c$)[5$ points$]$ The workstation is moved close to the wall opposite the machine, $70$ feet

away, and surface treatments are applied to the room to increase the average sound

absorption coefficient $$ to $0\mathrm{.}18.$