In the past years noise control laws have been adopted and enforced by State and Local governments. The Federal Noise Control Act of 1972 was the first nation-wide regulation concerning truck noise. The regulation requires "total" truck noise levels not to be greater than 86 dBA when measured at 50 feet, and applies to speeds less than 35 mph.

This regulation went into effect on October 15, 1975. On January 1, 1978 the noise level was lowered to 83 dBA. The mufflers in our line will enable you to meet this lower noise level when properly applied.

Exhaust Noise: Since engine exhaust is usually a major contributor to total vehicle noise, it is essential to reduce it significantly below the desired total vehicle noise level. The following guidelines indicate how low the exhaust noise levels need to be to meet total vehicle noise levels of 86 dBA and 83 dBA.

Rating Chart for Exhaust Noise
levels measured in dBA:

Excellent
Good
Marginal

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under 77dBA
77 to 82 dBA
82 to 86 dBA

• Exhaust noise levels less than 77 will allow almost any truck to meet an 86 dBA level. The only exception is a vehicle with several other excessive noise sources.
• Exhaust noise levels between 77 and 82 dBA would enable a vehicle to meet an 86 dBA level if all other noise sources are normal.
• Exhaust noise of 82 dBA or higher generally will not allow a truck to have a 86 dBA unless all other noise sources are controlled.

NOTE: For a vehicle noise level of 83 dBA, the levels on the rating chart must be reduced by 4 dBA.

You will find some helpful advice on noise reduction in our "Tech Tips" area.