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flymo · 29-05-09, 03:01 PM

I dont think there is a national standard that is used for track days, I do know that the ACU race regulations are pretty specific and are often copied for this purpose.

The limit for racing is 105dB at a specific rpm that is based on the type and size of engine. A 600cc 2 cylinder engine should be measured at 5500rpm and the following technique used...

The noise test will be conducted with the microphone placed at 50 cm from the exhaust pipe at
an angle of 45° measured from the centre-line of the exhaust end and at the height of the
exhaust pipe, but at least 20 cm above the ground. If this is not possible, the measurement can

be taken at 45° upwards.

The 'slow' response setting on the meter should be used.

Guidelines for the use of Sound Level Meters
1. The Sound Inspector must arrive in sufficient time for discussions with the Clerk of the
Course and other Chief Technical Officials in order that a suitable test site and testing policy
can be agreed.
2. Sound level measuring equipment must include a compatible calibrator, which must be used
immediately before testing begins and always just prior to a re-test if a disciplinary sanction
may be imposed. Two sets of equipment must be available in case of failure of tachometer,
sound level meter or calibrator during technical control.
3. Before testing, the Sound Inspector should if possible liase with another official who has
noise test equipment including calibrators, in order to agree the accuracy of the official sound
level meter.
4. Tests should not take place in rain or excessively damp conditions. Machines considered
excessively noisy must be individually tested if conditions allow.
5. In other than moderate wind, machines should face forward in the wind direction.
(Mechanical noise will blow forward, away from microphone).
6. ‘Slow’ meter response must be used.
7. ‘A’ weighted setting on sound level meter.
8. Always round down meter reading, that is: 103.9 dB/A = 103 dB/A.
9. Type 1 meter: deduct 1 dB/A. Type 2 meter: deduct 2 dB/A
10. Below 10° Celsius: deduct 1 dB/A. Below 0° Celsius: deduct 2dB/A
All tolerances are accumulative. Action taken will depend on the sporting discipline concerned, and

decisions taken during prior discussions with the Clerk of the Course.

29-05-09, 03:01 PM	#7
flymo Member Mega Poster Join Date: Jan 2008 Location: North West Posts: 3,124	Re: Track day noise tests I dont think there is a national standard that is used for track days, I do know that the ACU race regulations are pretty specific and are often copied for this purpose. The limit for racing is 105dB at a specific rpm that is based on the type and size of engine. A 600cc 2 cylinder engine should be measured at 5500rpm and the following technique used... The noise test will be conducted with the microphone placed at 50 cm from the exhaust pipe at an angle of 45° measured from the centre-line of the exhaust end and at the height of the exhaust pipe, but at least 20 cm above the ground. If this is not possible, the measurement can be taken at 45° upwards. The 'slow' response setting on the meter should be used. Guidelines for the use of Sound Level Meters 1. The Sound Inspector must arrive in sufficient time for discussions with the Clerk of the Course and other Chief Technical Officials in order that a suitable test site and testing policy can be agreed. 2. Sound level measuring equipment must include a compatible calibrator, which must be used immediately before testing begins and always just prior to a re-test if a disciplinary sanction may be imposed. Two sets of equipment must be available in case of failure of tachometer, sound level meter or calibrator during technical control. 3. Before testing, the Sound Inspector should if possible liase with another official who has noise test equipment including calibrators, in order to agree the accuracy of the official sound level meter. 4. Tests should not take place in rain or excessively damp conditions. Machines considered excessively noisy must be individually tested if conditions allow. 5. In other than moderate wind, machines should face forward in the wind direction. (Mechanical noise will blow forward, away from microphone). 6. ‘Slow’ meter response must be used. 7. ‘A’ weighted setting on sound level meter. 8. Always round down meter reading, that is: 103.9 dB/A = 103 dB/A. 9. Type 1 meter: deduct 1 dB/A. Type 2 meter: deduct 2 dB/A 10. Below 10° Celsius: deduct 1 dB/A. Below 0° Celsius: deduct 2dB/A All tolerances are accumulative. Action taken will depend on the sporting discipline concerned, and decisions taken during prior discussions with the Clerk of the Course. Last edited by flymo; 29-05-09 at 03:03 PM.