Superfluid 3He in silica aerogel provides a unique system for studying the effect of quenched disorder in the unconventional superfluid. We have performed longitudinal ultrasound (5.7 MHz) attenuation and sound velocity measurements of the superfluid 3He in 97% porosity aerogel. The attenuation and sound velocity were determined by direct propagation of sound pulses through the medium in a wide range of temperatures, down to 400 μK. The superfluid transition, marked by the increase in sound velocity, is substantially suppressed from that in 98% aerogel used in most of studies. The superfluid fraction determined from the sound velocity is less than 0.02 even at the lowest temperature.