A proper assessment of seismic reference site conditions has important applications as they represent the basis on which ground motions and amplifications are generally computed. Besides accounting for the average S‐wave velocity over the uppermost 30 m (), the parameterization of high‐frequency ground motions beyond source‐corner frequency received significant attention. , an empirical parameter introduced by Anderson and Hough (1984), is often used to represent the spectral decay of the acceleration spectrum at high frequencies. The lack of hard‐rock records and the poor understanding of the physics of introduced significant epistemic uncertainty in the final seismic hazard of recent projects. Thus, determining precise and accurate regional hard‐rock values is critical. We propose an alternative procedure for capturing the reference on regional scales by linking the well‐known high‐frequency attenuation parameter and the properties of multiple‐scattered coda waves. Using geological and geophysical data around more than 1300 stations for separating reference and soft soil sites and based on more than 10,000 crustal earthquake recordings, we observe that from multiple‐scattered coda waves seems to be independent of the soil type but correlated with the hard‐rock , showing significant regional variations across Europe. The values range between 0.004 s for northern Europe and 0.020 s for the southern and southeastern parts. On the other hand, measuring (and correspondingly ) on the S‐wave window (as classically proposed), the results are strongly affected by transmitted (reflected, refracted, and scattered) waves included in the analyzed window biasing the proper assessment of . This effect is more pronounced for soft soil sites. In this way, can serve as a proxy for the regional hard‐rock at the reference sites.