Question

4 (10 points) Two machines have similar performance and satisfy price requirement. The choice between the two machines is to be based on noise considerations. The octave- band sound-pressure level spectra of these two machines are listed below: Band, Machine A. Machine B, Hz dB dh 96 315 88 91 81 71 61 63 125 250 90 90 90 1000 81 56

Answer 1

It is clear form the data provided that both the machines i.e. Machine A and Machine B have similar performance and satisfy price requirement. The selection is to made on the basis of noise produced by both the machines provided the level of noise in dB.

As an engineer, the main aim of an engineer is to design a quiet workplace with maximum output, minimum input. Since both the machines have similar performance and they satisfy the price requirements of the company. So, the selection of machine solely depends upon the level of noise produced by Machine A and Machine B.

The table below shows the level of noise produced by Machine A and Machine B.

Band, Hz Machine A. Machine B dB 315 88 89 125 81 76 71 1000 81 8000

Table (1)

It is clear from the table provided that the Machine A will be preferred as the level of noise produced by Machine A are quite low as compared to level of noise produced by Machine B ob varied range of input bandwidth of signals provided as input to the machines.

Therefore, Machine A will be opted.