Why does newly paved asphalt sound so much quieter when driving over it?
In: Engineering
Roadwork engineers have figured out a mixture of asphalt with different pebble- and grain sizes, such that the surface is ultimately flat but “raw” with lots of cavities of different sizes. The flatness reduces noise generated by the tyres, while the rawness offers sufficient grip. The cavities act like sound absorbers. The different sizes of the cavities translate to different frequencies of the noise.
As you can guess, flatness and rawness are their respective couterparts to an extent. The trick is to find a compromise that is both: quiet and grip-offering as much as possible.
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