GB/T 18697-2002Acoustics -- Measurement of noise inside motor vehicles (English PDF)

3.1 Confirmatory test

The measurements performed are used to verify, whether the motor vehicles

provided by the manufacturer meet the noise requirements.

3.2 Check test

The measurements performed are to check whether the noise of the motor

vehicle is within the specified limits AND whether there has been a significant

change, since the motor vehicle is submitted, or between motor vehicles which

are submitted in different batches.

4.1 The reading of the sound level meter used shall use the "F" time-weighting

characteristic.

4.2 The measured value of all measuring points, in the confirmatory test and

the check test, shall be A sound level LpA, in unit of dB.

5.1 The sound level meter shall meet the requirements of Type 1, which is

specified in GB/T 3785.

5.2 If other measurement systems are used, such as tape drives or level

recorders, their electroacoustic performance shall meet the requirements of

Type 1 in the relevant clauses of GB/T 3785.

5.3 In order to measure the noise spectrum, the filter shall meet the

requirements of GB/T 3241.

5.4 At the beginning and end of each measurement, the acoustic performance

of the measuring device must be checked, in accordance with the

manufacturer's instructions. It is best to use an acoustic calibrator (such as a

piston sounder) for calibration. The sound level meter shall meet the

requirements of Type 1, which is specified in GB/T 3785, within the effective

calibration period.

5.5 For automobile acceleration tests, it is particularly recommended to use a

dual-channel recording device, which can record noise and vehicle speed

signals at the same time. It can obtain a graph of the relationship between

vehicle noise and vehicle speed.

5.7 The accuracy of measuring instruments for vehicle speed and engine speed

shall be 3% or better.

6.1 The measurement location must meet the following conditions, that is, the

sound radiated from the motor vehicle can only become a part of the noise

inside the motor vehicle, through the reflection of the road surface; it cannot

become the noise inside the motor vehicle, through the reflection of buildings,

walls or similar large objects outside the motor vehicle.

6.2 The air temperature outside the motor vehicle must be in the range of -5°C

to +35°C. The wind speed, at a height of about 1.2 m, along the measurement

route, shall not exceed 5 m/s. Other meteorological conditions shall not affect

the measurement results. The wind speed and wind direction, for the direction

of motor vehicle, shall be stated in the test report.

8.1 Engine and tire conditions

During the measurement process, all operating conditions of the engine, such

as fuel, lubricating oil, ignition timing or fuel injection time, shall comply with the

manufacturer's requirements. Before the start of the measurement, the engine

shall stabilize, within the normal operating temperature range; OR drive a

distance, at a moderate speed.

8.2 Vehicle load

The basic conditions of vehicle load shall comply with the provisions of 4.4 or

4.6 in GB/T 3730.2-1996, which are the same as those, as required by motor

vehicle manufacturers. The motor vehicle must be unloaded, when testing

noise (except for the driver, measurement personnel, test equipment, no other

loads are allowed).

8.3 Openings, windows, auxiliary devices, adjustable seats

Openings, such as sunroofs, all windows, air inlets, air outlets, must be closed

if possible. They shall be opened, only when it is necessary to study their

influence on the internal noise of the motor vehicle.

8.4 Vehicle operating conditions

The operating conditions, that can represent the interior noise of the tested

vehicle, shall be selected from the following three operating conditions.