Signs and symptoms
The warning signs of early speech delay are categorized into age-related milestones, beginning at the age of 12 months and continuing through early adolescence.At the age of 12 months, there is cause for concern if the child is not able to do the following:

Using gestures such as waving good-bye and pointing at objects
Practicing the use of several different consonant sounds
Vocalizing or communicating needsBetween the ages of 15 and 18 months children are at a higher risk for speech delay if they are displaying the following:

Not saying "momma" and "dada"
Not reciprocating when told "no", "hello", and "bye"
Does not have a one to three word vocabulary at 12 months and up to 15 words by 18 months
Is unable to identify body parts
Displaying difficulties imitating sounds and actions
Shows preference to gestures over verbalizationAdditional signs of speech delay after the age of 2 years and up to the age of 4 include the following:

Inability to spontaneously produce words and phrases
Inability to follow simple directions and commands
Cannot make two word connections
Lacks consonant sounds at the beginning or end of words
Is difficult to understand by close family members
Is not able to display the tasks of common household objects
Is unable to form simple 2 to 3 word sentences

Effects
Studies show that children diagnosed with speech delay are more likely to present with behavioral and social emotional problems both in childhood and as adults. Decreased receptive language, reading, and learning skills are common side effects for children that have a speech delay and do not receive adequate intervention.
Physical and occupational therapies can be used for a child that has a speech delay due to physical malformations and children that have also been diagnosed with a developmental delay such as autism or a language processing delay. Music therapy has effective results in the fundamentals of speech development, including phonological memory, sentence understanding, sentence memory, and morphological rule generation. Children that have been identified with hearing loss can be taught simple sign language to build and improve their vocabulary in addition to attending speech therapy. The parents of a delayed child are the first and most important tool in helping overcome the speech delay. The parent or caregiver of the child can provide the following activities at home, in addition to the techniques suggested by a speech therapist, to positively influence the growth of speech and vocabulary:

Reading to the child regularly
Use of questions and simple, clear language
Positive reinforcement in addition to patienceFor children that have a physical disorder that is causing difficulty forming and pronouncing words, parents and caregivers suggest using and introducing different food textures to exercise and build jaw muscles while promoting new movements of the jaw while chewing. Another less studied technique used to combat and treat speech delay is a form of therapy using music to promote and facilitate speech and language development. It is important to understand that music therapy is a newer therapy and has yet to be thoroughly studied and practiced on children with speech delays and impediments. See also
References
Further reading
Kennison, S. M. (2013). Introduction to Language Development.