A generalized harmonic analysis of ultrasound waves propagating in cancellous bone

Two longitudinal waves, called fast and slow waves, can be observed in ultrasound signals propagating through in vitro cancellous bone. From the propagation properties of both the fast and slow waves, an estimation of the bone status can be made. However, in in vivo measurements, a wide overlap of the fast and slow waves in the time domain is generally observed. In this study, a derivation of the characteristics of the fast and slow waves was attempted using a generalized harmonic analysis. From the results of this analysis, the times of the leading edges, frequencies, and amplitudes of the fast and slow waves were derived. These derived characteristics were scarcely influenced by the noise when the noise level was low. When the noise level was high, the derived frequencies and amplitudes were influenced by the noise, but the times of leading edges generally were not. (C) 2014 The Japan Society of Applied Physics