The COVID-19 pandemic has brought i a tough time to the people all around the world. The lockdowns have gracefully given us a lot of time to think and reflect on ourselves. One of the positive side of the lockdown is that people have stopped roaming the streets which were once busy with hustle and bustle. The streets are now calm as smooth sailing water. No one is sure whether the chirping of birds existed even before the lockdown was initiated.Nature has truly taken over the city with its music but the sound of an orchestra of tyres have its own charm and pleasure which can be heard and sustained in our memory in disbelief.
Around the world, the symphony of sounds created from objects that were mere materials to humans are now being heard. One of the most important part in the orchestra that our environment presents is the sound of a car that is moving at about 40 Kmph. If you increase the speeds you can hear the tyres registering 80 decibels which is about the same volume as that of a train heard from about 50 feet away. Interestingly, the sound is loud enough to cause hearing damage if a person is exposed to it for one whole day.
Now, if you are wondering how tyres make such high levels of sound, the only explanation to it would be that the rolling tyres makes sound when the contact patch that is the rubber touches the tarmac. The curved shape of the tyre and the road acts like a big horn of a trumpet which amplifies the original sound by 10 to 20 decibels in both direction when the front and the rare tyres roll.
Also See:Everything To Know About Tyre Manufacturing
The interesting question of "what is being amplified?" would have come into your mind. Well the sound is the disturbance in the air which carries the signature of the material that created it. If we consider a musical instrument, the quality and note that we hear depends on the physical structure of that instrument. A trumpet has a tube with air passing through it which makes the sound and a violin has a string which generates the sound depending on the vibration so the bigger question is what does a tyre have in them to produce sound?
The answer to that is simple. A tyre is a mixture of different instruments, all playing together not in tune. As the front tyres slam on to the tarmac, air is rapidly forced out of the gaps in the tread of the tyre which acts like a miniature trumpet. Air is sucked back into the gaps when the rear tyres leave the road and a sticky rubber pops off the tarmac something which seems to sound like a percussion instrument. When we try turning the wheels, the tyres slips and then again acquires grip. This continuous action of the tyres forces it to vibrate like a violin does. when the sidewalls of the tyre vibrates, it makes sound like a double bass.
The sound that a tyre makes vary depending on the size, shape and orientation of its various tubes, rubber blocks and grooves. The faster a vehicle is driven, the more the sound. This is one of the major reasons why tyre manufacturers focus on reducing tyre noise by balancing the components better to keep the cabin of a vehicle noise-free.
The tone is also affected by the kind of road. A porous road reduces the violence with the air that slams around the tyre grooves, reducing the creation of sound.
Tyres are one of the complicated subjects which acts like a musical instrument that the scientists are working towards understanding in terms all its nuances. As long as research on tyres remain, there is a lot to learn from them.
