where P is the acoustic pressure measured at point x, P0 is an initial pressure at a reference point, Δx is the distance from the reference point and α is an attenuation coefficient. Scatter can be a large contributor to these losses. Typical ultrasound frequencies used in battery metrology are in the 200 kHz -50 MHz range. The corresponding wavelengths (hundreds of microns at the MHz range) are much larger than the typical particle size (20 𝜇m or less) in an electrode, meaning that Rayleigh scattering dominates. As a result, scattering losses dramatically increase at higher frequencies and there is a tradeoff when choosing the frequency in an experiment: higher frequencies can provide better spatial and temporal resolution to measurements, but at the cost of signal intensity and penetration depth.