At Kohout's we know Exhaust. Whether you just need a
clamp fixed on your muffler, or you are interested in custom performance
exhaust systems, we can get the job done!
With highly trained exhaust technicians and the
capability to custom bend exhaust pipes to fit any make or model of
vehicle, Kohout's is the place to bring your vehicle for all your
exhaust needs!
Custom and Performance Exhaust Systems - Get the power and sound
you are looking for!
Catalytic Converter Replacement -
Custom bending of exhaust pipes to fit any make or model of
vehicle.
If you've ever heard a car engine running
without a muffler, you know what a huge difference a muffler can make to
the noise level. Inside a muffler, you'll find a deceptively simple set
of tubes with some holes in them. These tubes and chambers are actually
as finely tuned as a musical instrument. They are designed to reflect
the sound waves produced by the engine in such a way that they partially
cancel themselves out.
Mufflers use some pretty neat technology to cancel out the noise. In
this article, we'll take a look inside a real car muffler and learn
about the principles that make it work.
Inside a
Muffler
Located inside the muffler is a set of tubes. These tubes are designed
to create reflected waves that interfere with each other or cancel each
other out. Take a look at the inside of this muffler:
The exhaust gases and the sound waves enter through the center tube.
They bounce off the back wall of the muffler and are reflected through a
hole into the main body of the muffler. They pass through a set of holes
into another chamber, where they turn and go out the last pipe and leave
the muffler.
A chamber called a resonator is connected to the first chamber
by a hole. The resonator contains a specific volume of air and has a
specific length that is calculated to produce a wave that cancels out a
certain frequency of sound. How does this happen? Let's take a closer
look ...
The Resonator
When a wave hits the hole, part of it continues into the chamber and
part of it is reflected. The wave travels through the chamber, hits the
back wall of the muffler and bounces back out of the hole. The length of
this chamber is calculated so that this wave leaves the resonator
chamber just after the next wave reflects off the outside of the
chamber. Ideally, the high-pressure part of the wave that came from the
chamber will line up with the low-pressure part of the wave that was
reflected off the outside of the chamber wall, and the two waves will
cancel each other out.
The animation below shows how the resonator works in a simplified
muffler.
Waves canceling inside a simplified muffler
In reality, the sound coming from the engine is a mixture of many
different frequencies of sound, and since many of those frequencies
depend on the engine speed, the sound is almost never at exactly the
right frequency for this to happen. The resonator is designed to work
best in the frequency range where the engine makes the most noise; but
even if the frequency is not exactly what the resonator was tuned for,
it will still produce some destructive interference.
Some cars, especially luxury cars where quiet operation is a key
feature, have another component in the exhaust that looks like a
muffler, but is called a resonator. This device works just like the
resonator chamber in the muffler -- the dimensions are calculated so
that the waves reflected by the resonator help cancel out certain
frequencies of sound in the exhaust.
Whether you understand the theory behind it or not, a sound exhaust
system is a necessity. Have it inspected regularly.
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