In many countries experiments with different types of road surfaces have produced such products as “whisper concrete,” where some of the aggregate is left exposed and consequently there is only random tire contact.
Katika nchi nyingi majaribio ya aina tofauti za nyuso za barabarani yamezalisha bidhaa kama vile "sauti ya kunong'ona," ambapo baadhi ya jumla huachwa wazi na hivyo basi kunatokea mguso wa tairi bila mpangilio.