Without maternal instinct we never would have got here.

As to relationship of sound to babies' needs, the nature of the instinct is to pay attention to the cry.

It is not necessary to regard a cry as a language to be decoded. Try being a parent and you will discover that rhythm and routine help organize the seeming chaos of instinct. With routine you can make predictions.

You will also discover that as children develop, they respond well to some routine, which should be surprising in the same sense that we respond instinctively to the diurnal cycle, and are at least highly sensitive to the lunar and seasonal cycles, and the cycles of life. Look no further than human language to see the significance of instinctive cycles in human affairs, and notice that we learn and teach these cycles reflexively.

The sensitively to detect cycles and modulate responses constitute the meaning of the term "instinct" in this article.

The cry, which due to instinct is both manifest and cannot be ignored, primes and sustains the maternal attention from which parental care cycles emerge.

Sadly, in this era of hyper rationality and verbalization of everything in a perverse reason-as-first-principle for every feature of life, obsessive compulsive imposition of plans over nature may cause some new parents to think babies cry in some arcane jargon that can be deciphered by expertise into clear declarations of their needs. Cries don't work like this, but you can learn a routine.