Law for the “Un-sound”

Last week, a City Councilor proposed to update the Anti Noise Ordinance of Cebu by introducing a measure that will seek to impose a hefty increase in the fines against motorists who will modify their vehicle mufflers.

Councilor Cabarrubias sought to increase the penalties of those who "use or operate any motor vehicle so modified or removed muffler as to cause loud and unnecessary or unreasonable noise, including the noise resulting from exhaust, which is clearly audible from the nearby properties and unreasonably disturbing to the quiet, comfort, or repose of the other persons".

So what is a muffler and why are motorist driven to modify these?

Mufflers are decades old vehicle devices that minimize noise levels in the exhaust systems of a car. If you've ever heard a car engine running without  these, you'll  know what a huge difference this device can make to the noise level of your car's exhaust system.   Inside a muffler, you'll find a deceptively simple set of tubes with some holes in them bunched together with sound deadening material like fiberglass strands or fire resistant foam . These are designed to reflect the sound waves produced by the engine in such a way that they partially cancel themselves out. These tubes and chambers are actually fine tuned by the car manufacturers like a musical instrument.

There are different types of mufflers that can reduce exhaust noise. The most conventional and widely used muffler  is called the "glass pack" which use absorbent materials like fiberglass to reduce the sound. On a muffler like this, the exhaust goes straight through a pipe that is perforated with holes. Surrounding this pipe is a layer of fiberglass insulation that absorbs some of the pressure pulses. A steel housing surrounds the insulation.

One important characteristic of mufflers is how much backpressure it  produces  from exhaust gases. Because of all of the turns of the exhaust pipes and holes the exhaust gases have to go through, mufflers  produce a fairly high backpressure. This subtracts a little from the power of the engine. Performance mufflers produce much less  restriction or backpressure, but do not reduced the sound levels as much as Original Equipment Manufacturer(OEM) mufflers.

The other characteristic of mufflers is how they produce exhaust notes. Modern OEM Mufflers are relatively very good silencers . But for the boy racers and aficionados, stock mufflers are simply dull and uninteresting.

Performance Cars,  Sportsbikes  or "Big Bikes" have distinct exhaust notes that, in stock form, rarely poses as a nuisance.  I cannot say the same for Mopeds(low powered motorcycle variants) with modified/aftermarket mufflers.

In Japan, where the passion for motorsports is as strong as ours is for basketball, they made an government sanctioned group solely tasked to regulate legal specifications for performance mufflers and exhaust systems. JASMA or Japanese Automobile Sports Muffler Association oversees the products of all exhaust systems manufactured or brought in to Japan.  JASMA compliant mufflers operates below 120 decibel.

The ordinance will be a good step in eradicating unreasonably noisy motor vehicles but will need a few sharp teeth to be implemented correctly. Clearly the most important of which will be a good, reliable implementing body equipped with very good and reliable sound meters equipment. Without these, it'll be interesting to see how they will proceed in ticketing a Harley escorted by a Black SUV.