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Estimating the losses of ultrasound signal energy with propagation depth as a function of frequency is essential for quantifying tissue properties. Specifically, ultrasound attenuation is used to correct for spectral distortion prior to estimating quantitative ultrasound parameters to assess the tissue. Ultrasound attenuation can also be used independently to characterize the tissue. In this chapter, we review the primary algorithms for estimating both the local attenuation within a region of interest as well as the total attenuation between a region of interest and an ultrasound source. The strengths and weaknesses of each algorithm are also discussed.

The FIRAS and DIRBE experiments on COBE will provide data that strongly constrain models of Population III stars and dust. This paper describes the analysis procedures necessary to process COBE data, and compares simple Population III models to the preliminary COBE data.