  We have performed longitudinal ultrasound (9.5 MHz) attenuation measurements
in the B-phase of superfluid $^3$He in 98% porosity aerogel down to the zero
temperature limit for a wide range of pressures at zero magnetic field. The
absolute attenuation was determined by direct transmission of sound pulses.
Compared to the bulk fluid, our results revealed a drastically different
behavior in attenuation, which is consistent with theoretical accounts with
gapless excitations and a collision drag effect.
