The ultrasonic attenuation coefficient of a fluid or solid material is an acoustic parameter routinely estimated in nondestructive evaluation (NDE) and biological tissue characterization. In this paper, a new measurement and analysis technique for estimating the attenuation coefficient as a function of frequency for a fluid or solid is described. This broadband technique combines two established concepts in attenuation coefficient estimation: (1) frequency spectrum amplitude ratios of front surface, first back surface, and second back surface reflections from interfaces of materials with plate‐like geometries, and (2) equivalent diffraction points within the transducer wave field. The new approach yields estimates of the attenuation coefficient, reflection coefficient, and material density without the need to make diffraction corrections. This simplifies the overall estimation process by eliminating the transducer characterization step, that is, by eliminating experimental characterization of the effective radius and focal length of the transducer which are required when careful calculated diffraction corrections are applied. In this paper, attenuation coefficient and reflection coefficient estimates are presented for water and three solids with estimates based on measurements made with two different transducers. © 2003 American Institute of Physics