According to a report in the authoritative medical journal JACC Advances, one of the main culprits of road rage is the noise in the car. Long-term exposure to noise above 65 dB can cause sympathetic nervous tension and blood pressure fluctuations. To put it bluntly, noise can cause high blood pressure. It can even affect the visual organs, causing symptoms such as eye pain and vision loss.
Obviously, when the noisy car environment encounters congested urban commuting traffic, it is indeed very frustrating. When blood pressure rises, it is accompanied by irritability, excitement, and anger. Referred to as "road rage." So for our own health, and to avoid safety risks from road rage, we need to do two things: make the environment less noisy, and avoid congested roads as much as possible.
Basic situation of the test
As for avoiding congested roads, we can use the "avoiding congestion" function of the navigation software to find a smoother driving route. So what should we do to make the environment less noisy? What to do? Maybe after reading today's actual test, you will know.
Test environment: closed test site, standard painted cement test track
Weather conditions: Sunny, temperature 27℃
Test vehicle: Tesla MODEL Y
Measurement tools: decibel meter, electret condenser microphone, Denon audio power amplifier, Dan Take the unit bookshelf speaker
to test the suitable tires: ordinary tires/Thor Jingyue Pro silent cotton tires
Test items: tire noise
flame combustion comparison experiment
We install a high-precision electret (capacitor) microphone in the car for recording Noise signal inside the car. The tester drives the vehicle at a constant speed on a smooth asphalt road, keeping the vehicle speed at 60km/h. The operator uses a microphone to record the noise signal in the vehicle at a specified position and archives the signal.
The entire test was conducted twice in total. In the first test, the vehicle was equipped with ordinary original tires that are mainly economical and wear-resistant; while in the second test, the vehicle was equipped with professional silent tires with the pattern model: Thor Jingyue pro. This is a high-end tire with silent cotton, and it is also a product optimized and developed for new energy vehicles.
After 2 tests, we have 2 different car noise signals in our computer. We brought 2 signals into the audio laboratory and input the signals into the amplifier at the same time. The amplifier drives 2 bookshelf speakers respectively. This speaker is an inverted speaker, and when it is working, there will be airflow in the inverted tube. The more energy the bass signal has, the stronger the airflow will be.
Test result evaluation:
We placed burning candles in front of the inverter tubes of the two speakers. The left side plays the interior noise of normal tires. On the right, the in-car noise of Thor Jingyue Pro is played. Use the principle of sound wave vibration to observe the beating amplitude of candlelight. The more intense the flame jumps, the stronger the airflow in the inverter tube is, which reflects the greater the noise from the tires.
You can see that the flame of the candle in front of the inverter tube of the left speaker is beating violently and is almost extinguished; while the flame of the candle in front of the inverter tube of the right speaker is obviously much calmer. Through experimental comparison, I can judge that the rolling noise of Raytheon Jingyue Pro is lower than that of ordinary non-silent tires. Through experimentation, we determined that silent tires actually work.
Experiment summary: What does the
experiment show? The reason why the
experiment can show such results is mainly related to the noise spectrum. The noise emitted by tires when they are rolling can cover approximately 40 to 4000 Hz, which is the range from bass to mid-range and high treble. The higher frequency noise is easily "solved" by the body's sound insulation, so it is almost imperceptible to the human ear.
And the bass noise of 150~250Hz is difficult to solve through vehicle body sound insulation. It can easily be introduced directly into the car through the metal structure of the car chassis. It sounds like a dull buzzing sound to the driver and passengers, commonly known as "muffled sound".The "radiated power" of the bass signal is much higher than that of the mid-range and high-pitched sounds, so it is difficult to process.
At present, the method of sticking special silent cotton inside the tire has been proven to be really effective. For example, the Leishen Jingyue pro tires used in this test are affixed with polyurethane silent cotton that is specially optimized and designed with greater thickness, higher density, and larger volume. It can effectively absorb noise in the 150~250Hz range, thereby achieving the purpose of quietness and comfort. Especially for new energy vehicle users, the sound insulation of the vehicle itself is already good enough. At this time, the "muffled sound" from the tires will give us more headaches.
