If you have ever seen and talked to a baby, you probably noticed yourself doing something very strange. Instantly, you start to talk in a different tone of voice while saying weird stuff you otherwise would never. But why do we suddenly change the way we talk when talking to an infant?
The kind of talking I just described is colloquially known as ‘motherese’ or more formally as infant directed speech (IDS), and it differs significantly from adult directed speech (ADS).
IDS has been reported in every known language tested to date. It has basic sound features that make it unique: a higher fundamental frequency (basic pitch levels), more intense and exaggerated contours and slides, and more repetitive and rhythmical elements.
But why do we speak this way to babies?
It has been found that IDS is crucial to both babies and adults for different reasons.
Babies prefer to listen to IDS compared to ADS almost as soon as they are born, irrespective of whether it’s spoken by a man or woman. This preference for IDS has even been found in infants born to deaf parents. IDS provides a reliable way for adults all over the world to trigger positive reciprocal response from their young. It’s a method by which we can attract their attention and potentially modify their behaviour, at a developing stage when verbally reasoning with a baby is tempting but largely pointless.
Another main advantage of IDS for adult is that we get a smile. When we speak to a baby in musical tones, we often get positive feedback that is, frankly, adorable.
This happy response has the benefit that the baby is not crying. Scientific evidence shows that parents experience a release of stress hormones in the brain on hearing a baby crying.
As much as a baby’s cry can be distressing, once upon a time it was downright dangerous. A screaming baby would have been no good to our ancestors if they were trying to hide from predators or allow their community to get valuable rest in order to restore energy levels.
As such it’s an extremely useful survival skill to be able to create a state of calm in a baby by low-energy methods that require only our voices.
In modern times this calming technique remains useful in situations where the baby’s natural response is not necessarily productive or desirable, such as when they must have a vaccination or try new food.
The first obvious benefit of IDS is that babies can respond to adults using these sounds. They can’t talk to us yet but they can produce coos, pitch glides, and rhythmic responses. When we interact with babies they mimic our IDS, and in doing so the baby guarantees a safe and nurturing environment.
One of the oldest functions of musical IDS was probably able to communicate emotional state. IDS exaggerates the features of our own emotional speech, such as high-pitched, fast sounds when we are happy and low-pitched, slow sounds when we are sad. Not only do caregivers use these features of IDS to communicate emotional information to babies, they also use them to modify a baby’s emotional state.
Another research concluded that IDS contains musical features that can help babies to learn about different vowel types long before they are able to make use of this information. Our musical speech may therefore help our young to build the foundation of their language learning.
Source: You Are The Music by Victoria Williamson