“People often quote 22 dB/cm/MHz attenuation of ultrasound. Decibels are a logarithmic scale, so with 1.4 cm of roundtrip skull distance, and typical fUSI frequencies of 10 MHz, this would be 14 orders of magnitude of attenuation! In physics, there's a word for 14 orders of magnitude of attenuation. It's called zero, i.e., you will measure nothing.

But where did the 22 dB/cm/MHz attenuation number come from? We were skeptical…”