According to Crowe and McLeod (2020), all speech sounds should be acquired by 6 years, 11 months. This means that by the time a child enters 2nd grade, they should be able to produce all speech sounds, even the more difficult sounds like /r/ in red and /th/ in with. When a child is unable to produce speech sounds and they are difficult to be understood by familiar and unfamiliar listeners, they may have a speech sound disorder. A functional speech sound disorder may be characterized by articulation errors or phonological errors. These types of speech sound disorders are idiopathic, meaning there is no known cause. Articulation errors are characterized by motor aspects of production, typically manifested by substitutions and distortions, such as saying “wabbit” for rabbit or “flowuh” for flower. This type of SSD occurs because of difficulty producing the sound. Phonological errors are characterized by difficulty understanding the linguistic aspects of sounds. Typically, they are manifested by pattern-based errors. For example, saying the word “tea” for key or “dote” for goat symbolize the phonological pattern of fronting. This means that all sounds that should be produced in the back of the mouth are produced in the front of the mouth. This is due to difficulty understanding that sounds can change the meaning of words.