I’m gonna drop a little education on a speech impediment I have: a stutter!
Why? Mainly because most people write stutters terribly and it annoys the heck out of me.
So, let’s start with the basics:
Stutteringis a speech disorder. Most people think of it as being where the flow of speech is interrupted by the involuntary repetition of sounds, words, or phrases (this is the sterotypical stutter you see in movies, though even that’s inaccurate which I’ll get to later). However, it also involves involuntary prolongation of sounds (I call it getting stuck on a sound, cuz that’s what it feels like. when this happens for me it is like I lengthen a word for no apparent reason. “geeeeeeting mmmmmilk. Want some?” type of thing), and involuntary stops (it’s like my mouth just dammed up the flow of words here - I know exactly what I want to say, I just can’t get my mouth to say it. This is the most frustrating because when I can make words I can still speech-communicate but if I have a stubborn stop I can’t at all - autistic loss of words feels very similar but more long lasting and also sometimes involves language structure and word retrieval as well). Lastly, it can also involve involuntary insertion of meaningless sounds - ums, ahs, and ers are pretty common. Some stutterers, me included, often curse when we’re having trouble as well (and I dunno why but the curse for me usually comes out pretty easily even though the sentence itself is not. Don’t ask me why, but it happens - I think cuz speaking with a stutter is like trying to hold onto a handful of sand where the harder you try to say something, the harder it is to say.
Now, how does stuttering happen in real life?
For one, people who stutter usually have more trouble at the start of the sentence, and less as it goes on. Movies almost always get this wrong. A person who writes stutters well would write “I have a stutter” with a severe stutter less like this:
“I-I, uh, I have, uuuuh, I hhhhhh- fuck - I hhhhaaaaa, um, I have- I have a- um, I have a stutter.”
Do you get the difference? It starts off with a lot of trouble at the beginning, and gets smoother as you work through.
Secondly, stutters are variable. Meaning they change depending on the situation. For me, the more anxious I am, the more I stutter. The more angry I am, the more I stutter (often, I can’t communicate aloud at all if I’m furious, my involuntary stops get so bad. I can have a whole speech I want to say in my head and nothing can get out and it just makes me more furious). On the other hand, if I’m calm or relaxed, I often don’t stutter at all. That movie or book character who has a severe stutter always and forever without ever changing? Doesn’t really happen very often. There are people like that, but not many. Far more common are people like me, who can talk effectively - maybe not completely fluently, but who can make effective communication in a fairly efficient manner - some or even a lot of the time, but who in some situations can’t talk well or at all. And sometimes, there’s a person who doesn’t seem to stutter at all (probably does but not in a way that people who don’t know stutters will notice) a lot of the time, who will in a high stress situation suddenly have a really hard time communicating.
Thirdly, a lot of people with stutters have more trouble with certain phrases or sounds than with others, and will try to rephrase their thoughts if they know that what they’re about to say is going to hit a lot of trouble. This is why I am absolutely terrible at oral exams - the stress of the exam drives my stutter into overdive (though I can give a talk without stuttering, go figure - I imagine because it’s scripted cuz scripts seem to help for me), and sometimes I literally can’t give the correct answer because I can’t say it, and instead of just giving the oral exam, it’s like I’m doing a second exam at the same time trying to figure out how I can actually get what I want to say out around my stutter.
Fourthly, stuttering is not just a kid thing. People of any age can stutter, and less than 1 in 5 of those who stutter past age 5 will stop stuttering before adulthood. Toddlers, however, very often start stuttering and then have their stutter resolve on its own within two years. Teenagers and adults who stutter will never not stutter. Those stutters do not resolve - though they may reduce in severity. However if your story has the main character magically not stuttering anymore ever? Not going to happen. Learning to make peace with their stutter and communicate effectively around it even when it’s acting up, on the other hand? Actually happens.
Lastly, how to help stuttering: Drawing the person’s attention to the stutter, teasing them, pressuring them to speak more quickly, advising them to stop and take a breath or take their time or what have you, and in general applying negative social pressure to stuttering are all counter-productive. By which I mean they make stuttering worse, and make it harder to speak smoothly.
What actually does help? On a one-on-one basis, basically shutting up and letting the person with a stutter do their thing to get the words out without input or judgement. If what they want to say is obvious, you can substitute a word now and then (sometimes it helps me get past a block for someone to do that), but don’t play 20 questions and definitely don’t do any of the stuff in the previous paragraph.
Additionally, I am told that modern therapy is helpful. Speech therapy I had as a kid was overall less than useful (with the exception of teaching me to try to re-phrase stuff I was blocking on which actually did help with real communication but the “concentrate on your mouth to make the sounds” stuff just made it worse honestly), but apparently it’s changed since then.
And all of that ^^ should give you a start on how to write stuttering properly - though you should still do a lot of research on it and talk to people with stutters about their experience with stuttering stigma and stuff like that about how to deal with it.
EDIT: I should note that a user messaged me with a good point that I thought should be included, and that is this: not all people with stutters find the same things helpful. Frex, I find it useful if I’m completely blocking on an obvious word for someone else to substitute it, but this user absolutely hates that. If you know someone who stutters, ask before you start substituting words or anything like that - they’ll tell you what helps them.