This paper defines the echo signal-to-noise ratio (eSNR) for pulse-echo systems that adapts to the effects of shift-varying impulse responses, spatiotemporal coding, and various beamformers. Measurement techniques using point targets or random scattering media can be interrelated for a broad range of experimental conditions through the eSNR. The eSNR definitions are also illustrated by comparing a spatial matched filter (SMF) beamformer to conventional dynamic receive focusing methods to evaluate performance based on resolution and sensitivity. Closed-form expressions are presented that predict eSNR gains from SMF approaches relative to other beamformers.