Reliable and accurate measurements of acoustic attenuation enable correlations between the acoustic responses and properties of sediments to be attempted. This paper proposes a dynamic modeling technique which allows for a direct assessment of attenuation from changes in the signal spectral shape caused by absorption losses in the sediment. Using the frequencies corresponding to the signal spectral maximum and a point 3 dB below the maximum, attenuation data can be dynamically extracted. Laboratory experiments on three types of sand were conducted to validate the proposed method. Although the concept can be applied using any broadband sound source, a parametric array source was used in the study because of its broad bandwidth and definable wave shape. A comprehensive discussion on the different sets of data collected is given with an emphasis on the attenuation coefficient k and the exponent N of frequency. The results of the study demonstrate close agreement when compared with the accepted literature values. ¿ American Geophysical Union 1989