Sound Testing Procedures

The test area shall be cleared of all persons except test personnel.

The test area shall be furnished in its normal manner. All items affecting room sound absorption, such as drapes, furniture, carpeting, etc., shall be in place.

All windows and doors to the test area shall be closed.

Indoor tests shall be performed when outside noise levels are at a minimum.

When conducting sound tests, precautions shall be taken to keep the sound-testing meter and the operator from interfering with the measurements. The sound meter shall be removed from its case. The operator shall hold the sound meter at arms length and stand out of the line of the sound source, or mount the sound meter on a tripod. Some sound meters are provided with an extension rod or cables for mounting the microphone away from the sound meter body to avoid disturbing the sound field around the microphone.

Microphones shall be pointed toward or at an angle to the sound source, as directed by the manufacturer’s specifications. Microphones shall be placed in the test area at the height from the floor and distance from reflective surfaces that is specified in the manufacturer’s instructions. Sound-pressure measurements shall be taken with equipment on and off.

The procedure for measuring equipment under conditions of background noise is:

  • Measure the total noise level with the equipment running. This includes an octave band analysis.
  • Measure the background noise level with the equipment off.
  • Calculate the difference between the two readings. If the level of the total noise measured is less than 2dB higher than the background noise, the level of the background noise is too high for an accurate measurement.

If the difference is between 2 dB and 10 dB a correction shall be necessary. No correction shall be required if the difference is greater than 10 dB.

In some cases it may be necessary to take sound measurements on equipment at separate times and combine the readings to obtain a total sound pressure level in the event that both machines will operate at the same time. The procedure for combining reading is:

  • Measure the sound level on each piece of equipment.
  • Subtract the lower dB reading from the higher one.

If three pieces of equipment were present, the sum of the first two and the sound pressure level of the third machine would be used.


Vibration Testing Procedures

Ensure that there is no construction in progress that will interfere with the test.

Ensure that all construction equipment that might interfere with the test is off.

Ensure that any building vibration source, such as an elevator, that might interfere with the test is off.

Clean the equipment being tested of any grease, oil, or other substance that might cause slippage of the vibration transducer.

Clean the equipment being tested of any substance that might cause improper contact between the vibration transducer and the equipment.

Position the vibration transducer according to the manufacturer’s instructions.

Mount the vibration transducer so that it does not interfere with the operation of the equipment being tested.

Place all test instruments where they will not interfere with the operation of the equipment being tested.

Test each piece of equipment under actual operating conditions.

Test in all three directions; the x-axis, y-axis, and the z-axis.