Yes it is. To make it simple : when a substance is cooled to 0 Kelvin (absolute zero), its molecules stop moving completely. With no molecule movement, the speed of sound obviously drops to zero. For example, if we assume that the temperature in space is 0 Kelvin (it is actually slightly higher), U could "stand" right in front of someone (provided U both could breathe !!) & talk to him (even shout)... yet he wouldn't B able to hear U !
MF