Comprehensive Notes on Normal Language and Speech Development Part A

Foundational Concepts in Vocal Development and Child Communication

This course, overseen by Dr. Limor Adi-Ben Said at the Ono Academic College Department of Communication Disorders, addresses the normal development of language and speech. The preliminary portion focuses on the progression of vocal productions, which are systematically categorized based on their function and nature. Specifically, vocalizations are divided into two primary types: Reflexive and Non-reflexive.

Reflexive vocalizations refer to the physical and physiological activities of the infant, such as crying or coughing. These are considered automatic responses to physical states. In contrast, Non-reflexive vocalizations are non-automatic productions that contain phonetic components increasingly similar to those found in adult language. These phases mark the beginning of the child's journey toward expressive language and are detailed through specific developmental stages.

Stages of Vocal Development: From Birth to Jargon

Research by Stoel-Gammon and Menn ( $2013$ ) provides a comprehensive framework for the stages of vocal development. These stages reflect the physiological maturation and the increasing control the infant gains over their vocal apparatus.

Stage 1: Reflexive Vocalizations ( $0-2$ months). This earliest stage is characterized by the birth cry and other reflexive sounds. These include coughing, sucking, and various vegetative sounds. At this point, the infant lacks neurological and physical maturity, resulting in a lack of intentional control over the vocal system.

Stage 2: Cooing and Laughter ( $2-4$ months). During this stage, the infant begins to produce sounds associated with comfort and pleasure. These are often referred to as cooing sounds, which are both consonant-like and vowel-like. Most of these productions are "back sounds," consisting of guttural consonants and back vowels, which occur as the infant discovers the back of the oral cavity.

Stage 3: Vocal Play ( $4-6$ months). This stage involves repetitive sounds and random reflexive babbling rooted in "mouth play." The vocal play during this period is not yet intentional. Oller ( $1986$ ) describes this as Marginal Babbling, which occurs at the edges of syllable formation. Some infants in this phase may randomly produce isolated syllables in a Consonant-Vowel ( $CV$ ) structure.

The Emergence of Canonical and Variegated Babbling

Stage 4: Canonical Babbling ( $6$ months and onward). This is a critical milestone where the infant produces sequences of consonants and vowels ( $CV$ ) with timing similar to adult speech. Although these productions sound like words and are often interpreted as such by parents (who may assign meaning to them), they are not yet considered true linguistic words. There are two distinct types of canonical babbling observed during this period.

First is Reduplicated Babbling (also known as Lalling). This consists of repetitive babbling with fixed, doubled sequences such as "baba," "mama," or "dada." Second is Variegated Babbling (or Non-reduplicated Babbling). This involves syllables with a variety of different consonants and vowels, such as [bagidabu]. This form is also linked to Echolalia (mimicking sounds) and becomes more dominant around the ages of $12-13$ months.

Stage 5: The Jargon Stage ( $10$ months and older). This stage overlaps with the appearance of meaningful speech. It is characterized by sequences of sounds and syllables produced with a wide variety of stress patterns and intonation. It is frequently referred to as Conversational Babbling or Modulated Babbling because the infant sounds as though they are speaking in full sentences without using actual words.

Development of Communicative Gestures

Communicative gestures in infants are defined as formal movements whose primary function is to convey meaning that can be interpreted consistently within a shared interactive system between the child and the adult (Zinober & Martlew, $1985$ ). These gestures are performed with the specific intention to communicate and are typically expressed via the fingers, hands, and arms, as well as facial expressions and body movements (Iverson & Thal, $1998$ ).

Gestures are categorized into two main types: Deictic Gestures and Representational Gestures. Deictic gestures (Thal & Tobias, $1992$ ) do not have a fixed referential meaning tied to a specific object; instead, they are entirely context-dependent. They are produced to express communicative intent, draw attention to something, designate or declare something, or make a request. These can be used with a variety of objects, such as reaching for a cup, a spoon, or a teddy bear, or pointing at a dog, or a plane in the sky. These gestures are usually accompanied by vocalizations.

Masur ( $1990$ ) identifies four specific deictic gestures:

Showing: The infant holds out an object to show it to the adult.
Reaching: The infant reaches toward an object while looking at the adult.
Giving: The infant hands an object to the adult they are communicating with.
Pointing: The infant directs the adult's attention to something without touching it.

Representational Gestures and Their Role in Language

Representational gestures (Crais et al., $2009$ ) typically appear after the infant has already begun using several deictic gestures. Unlike deictic gestures, these have fixed and specific semantic content, representing stable referents. There is an inherent similarity between these gestures and the words they represent, acting as labels for different contents. The use of representational gestures increases at the start of the single-word stage but decreases as the child's use of conventional, agreed-upon words increases.

These gestures often emerge during ritualized games and routines used by adults or caregivers. Examples include putting a hand to the ear to represent a phone, bringing the finger and thumb close together to represent "small," waving for "bye-bye," shaking the head for "no," or clapping for "Bravo" (well done). While some of these are modeled after adult behavior, others may be original gestures invented by the child independently of any model.

Theoretical Perspectives: Babbling as a Bridge to Speech

The relationship between babbling and the appearance of first words/speech has been a subject of debate. Jakobson ( $1941/1968$ ) famously argued that there is no connection between these stages, suggesting a "silent period" exists between babbling and the onset of speech.

However, other researchers, including Stoel-Gammon, Vihman, Robb et al. ( $1994$ ), and Oller et al. ( $1976$ ), argue that there is a clear continuity between these stages. They posit that babbling is an essential and important marker for speech. Evidence for this continuity includes the high degree of similarity in sounds and phonological sequences between babbling and first words. Furthermore, infants show a preference for adult-like sounds in late babbling stages and use intonation curves to signify requests or resistance before they can produce words. Notably, babbling continues even after the first words appear. Consequently, babbling and spoken language are considered a normal, natural continuum in child development.

Early Language Comprehension in the Pre-Verbal Stage

Before an infant begins to speak, they develop early foundations of language comprehension. This development includes an awareness of the human voice and a preference for familiar voices. The infant will begin to reference the source of a sound and attempt to locate it. They listen intentionally to the characteristics of adult vocal productions and demonstrate anticipation and enjoyment of shared vocal games.

The infant eventually starts to attribute communicative intent to being called. They attempt to assign meaning to the vocal productions directed at them based on intonation, context, and facial expressions. This progress is evidenced by the infant's ability to respond appropriately to prompts and questions, such as "Where is the light?", "How does a fish go?", "Where is Dad?", or "Do bye-bye."