Interesting article on tire noise:
Some excerpts:
Speed of Sound: The Science of Tire Noise - Tire Review Magazine
Designing a quiet, comfortable tire for OEM applications is critical.
www.tirereview.com
Some excerpts:
...As you can imagine, the quietest tire is a smooth tread where no impact between the tread blocks and the road exists. The closer the tire pattern gets to a completely smooth tire, the quieter the tire gets. Tire manufacturers were able to reduce overall tire noise by 5 to 8 dB in the past 10 years. In some cases, modern tires have only 2-3 dB higher noise than smooth tires....
...Interior noise is transmitted inside of the vehicle through its structure and via air. Airborne noise consists of the progressive movement of mass particles (vibrations) and is transmitted in the form of soundwaves at the speed of sound to the vehicle cabin. Structure-borne noise is transmitted through the body of the vehicle through the tire. Exterior noise is transmitted outside through radiation and sound waves...
...The frequency of structure-borne and airborne noises shifts as the dominant inside noise as the result of changes in the vehicle’s speed. At lower frequency, normally at lower speeds, the structure-borne noise is the dominant type of noise. At a higher frequency range, normally at higher speeds, the airborne noise is the dominate type of noise....
...Structure-borne noise is normally around 160 Hz and is influenced by tire construction. Airborne noise is normally around 1,000 Hz and is influenced by a tire’s tread pattern...
...Tire noise is a very complex matter normally managed by a team of experts within tire companies who are experienced with NVH (noise, vibration and harshness). Because tire noise levels change internally and externally with the speed of the vehicle and the transfer through different sources, detecting and improving tire noise is difficult. However, with the advancement of prediction tools and a better understanding of noise sources, today’s tires are much quieter than their predecessors...