Most animals (including some very stupid critters) can recognize the voice of their parents. It is a low-level brain function hard-wired into animal physiology. This is not evidence of consciousness any more than it is for any other animal.
As has been pointed out elsewhere, the higher brain tissue is non-functional until several months after birth, and generally isn't fully "online" in any meaningful sense until a human is around two years old. This is one of the reasons humans don't have memory below a certain age; the parts of the brain that would store and process such memories don't function when you are born and slowly become operational over the first few years of life. The higher brain isn't fully functional until around the age of three.
Its too bad that false information was pointed out elsewhere and then repeated. There is no such thing as non-functional tissue in the brain. Neural function, esp. cortical function is progressively acquired. At any point in development, the tissues are functioning at their capacity. Development of the human brain follows a slow progression that peaks in the early teens. Fetal pain responses, speech, or the abilities of a 6 month old or 2 year old, are all milestones along that progression.