Counter-intuitively, Chris's speech impediment appears to have worsened over time. He spoke relatively clearly and normally in his earlier videos (outside saying "listen" as "risten"), while his stuttering and other difficulties have increased significantly since then.
Likely causes include troll-induced stress and a lack of conversational company not already accustomed to Chris's speaking tendencies.
Chris's problems in verbal communication potentially stem from either the extended period of "muteness" he went through during his childhood (supposedly as a consequence of his treatment by the abusive babysitter) or his autism, a disorder which often results in speech difficulties. Chris's written communication generally tends to be significantly more coherent and grammatically correct than how he speaks. While writing, he has more time and freedom to determine what he says.
Nervousness in general may also be a factor with Chris's stuttering issues. His early videos in which he stuttered less and spoke more fluently, comparatively speaking, were possibly rehearsed and may have required several takes before the final version. He was also within the comforts of his own room and house, and possibly felt more relaxed than he would in a normal social situation. When conversing with outside parties, such as trolls or random strangers out and about, he may feel more pressured to be sociable and thus, trip and stumble over his sentences. Another possible reason for his degenerative speech habits might be the increasing levels of paranoia Chris has over the belief that every person he comes into contact with might be a troll. This may be causing him to be become less comfortable around people more-so than he already was, and thus affects his communication skills greatly.
Slang such as "Y'all" and "'em", and contracting the "g" of words ending in "-ing" is typical in dialects of the southeastern United States, Chris's native region.
Chris's pronunciation of "nt" (Internet pronounced "Innernet") is a common trait of American accents.
Chris's diction is naturally staggered, interspersed with pauses, deep breaths, "um", "uh" and "hm". The pauses and deep breaths, used in speech therapy, suggest that Chris has had his speech impediment professionally treated at some point. Chris's protracted style of speaking seems to make it easier for him to lose his thought, stray off topic, or forget to include certain segments of his thoughts. However, in the Flipnotes he has made, his speech is surprisingly fluent, with no "ums" or "uhs". This fluency is probably because he is being timed to do it, so there's little time to stop.
Chris also has a strong tendency to stutter. Although not the type of "machine-gun" stutter largely associated with the problem, Chris constantly has to repeat whole phrases, and he stumbles over certain phrases as he finds the correct words to best convey his ideas. This also could be because Chris finds the need to correct himself, and finds repetition to be the optimal way to deal with this. Ofte- usually this resu- this resu- thi- th- this ends up in Chris having to rei- repe- this ends up in Chris having to shuffle through many synonyms just to express a brief statement (prime example: Kacey calls).
During the conversation with Kacey's dad, Chris claimed to pause before speaking in order to "spellcheck" what he is saying. This implies that Chris needs to consciously plan what he is going to say or else he is unable to say it; this suggests that Chris's difficulty with speech stems from poor contact between the speech centers of his brain and his cerebellum, a common characteristic of autism. Ironically, Chris clearly doesn't spellcheck his written work.
Like small children, Chris has a tendency to speak too quickly, run words into one another, and slur words. For example, Chris's pronunciation of "Ensykapeia Dramakka paysh".
Chris has difficulties with the post-vocalic L in words like real /ˈɹiːəl/ and medal /ˈmɛdəl/, pronouncing the "al" as an "o" (real becomes Rio, medal becomes meadow, jail rhymes with mayo, etc.)
Chris has difficulty pronouncing the letter "X" (/ks/ or /gz/), as well as related consonantal digraphs (/sk/, /st/), pronouncing it either as an "/s/" sound (elision) or as a "/t͡s/" sound (fronting); for example, he pronounces the number 6 as "sits". In addition, he pronounces the voiced "th" sound (/ð/) as "d", even when it's not deliberate (as in "da" standing in for "the"). This indicates trouble with consonants, known as articulation disorders. This may have also been caused by high-frequency hearing loss that Chris experienced as a young child (as noted by the autism papers).
However, given the above, it is most likely he has tachyphemia. This explains most of his speech and grammar usage.
Chris's singing voice
Main article: Chris and music#Singing
Chris's tomgirl voice
Chris has attempted to change his voice as part of his tomgirl transition. Though some MTF transsexuals are able to pull off a convincing female voice with practice, Chris isn't one of them. He opens his videos with a falsetto voice, but usually switches back to his natural voice at some point during a video.