Language and the brain – what you need to know about speech disorders

A life without speech?
When I was a teenager I heard the story of a close friend of mine, whose uncle had lost the ability to speak after he had a stroke. Uncle Peter used to be a very funny and talkative guy until the day the stroke occurred. From that on, he simply could not form a single sentence, because the stroke had damaged a part of his brain which was responsible for language production. And Uncle Peter is not a rare case, in fact there is an incredibly high number of people with a language deficit. 

More people like Uncle Peter?
It is estimated that in the UK alone, 2.5 million people suffer from a communication disorder of which 800,000 people are affected so severely that even their immediate families have a hard time understanding them (Cummings 2008). Perhaps you even know a person who is suffering from a speech disorder yourself? If not, think about your relatives, the families of friends or general acquaintances. In any case I am sure that even if you don’t know anyone personally, you will know someone who knows someone affected by it. Now you might ask yourself “Is there a way to help those affected by a language impairment” or “What can you do to preserve people from getting a speech deficit?” and this is where clinical linguistics comes into action.

What the heck is clinical linguistics?
Put simply clinical linguistics is the study of all the different ways in which human language can be distorted (Cummings 2008). This does of course include language disorders that come to your mind when thinking about the term, but clinical linguistics also deals with disorders you might not have on your radar. Since language is largely dependent on earlier evolutionary developments in humans (namely such mechanisms that make breathing, swallowing and feeding possible), a damage in the brain areas which make these functions possible can also result in disordered speech (Fava 2002).

Growing more and more important
The study of the relationship between language and the brain goes back to the early 19th century and has grown more and more important since then. Over the last decades there has been a tremendous increase in language disorders or disorders making language reception or production impossible, s
o it is no wonder that there is an increasing interest in that field. Due to this growing importance, the branch clinical linguistics was developed. Clinical linguistics however is not only an academic discipline dealing with researching brain functions or language disorders, 
but also an area of clinical practice. In order to help people with speech impairments, speech therapists are offering special therapies which aim at restoring language functions.  

‘Mistakes’ while speaking or speech disorder?
Of course everybody makes ‘mistakes’ while speaking from time to time. Whether it be mixing up words, repeating themselves or mispronouncing something, no human being speaks 100% correct at all times. This might be annoying or sometimes even embarrassing, but it is completely normal and not something to be worried about. However, there are people in this world who suffer from a speech disorder and are not capable of communicating the way “normal” people talk.

So what exactly is a speech disorder?
A speech disorder is a condition in which the correct understanding or production of speech is limited or not given at all. Usually a speech disorder occurs after the brain (most commonly the left side of the brain) is damaged. This is called aphasia. The most typical causes for an injury of the brain are strokes, tumors, intoxication, inflammations or internal bleedings after accidents. Aphasia is not a disease itself, but a cover term for several serious language disorders which are linked to brain damage (Steinberg 1993).

Language and the brain – how even does that work?
To fully understand the occurrence of aphasia we first have to find out about the connection between language and the brain. So let’s have a look at where language is located in your head. As you most probably know already there are two different sides of the brain, the left and the right side (also called hemispheres). Most language functions are located in the left hemispere (if you are righthanded), otherwise they are distributed more evenly between both hemispheres. In the brain they are mostly found on the cortex (the surface of the brain). Here you can see a picture of the most important regions of the human cortex:

The circle area in the front is called Broca’s area, because a scientist named Paul Broca discovered this part of the brain and its function, which is the production of speech. The part of the brain marked with a circle in violet is Wernicke’s area, once again named after the man who first found it. Wernicke’s area is responsible for the comprehension of speech. Both areas are connected by tissue which is called the arcuate fasciculus and makes cooperation between the two areas possible. If now the brain gets damaged and some of the parts involved in language understanding or production take harm from it, an aphasia occurs (Blank et. al. 2002).

Different forms of aphasia?
The most common types of aphasia are Broca’s and Wernicke’s aphasia, which means that the respective area of the brain is damaged. For patients suffering from Broca’s aphasia the speech production is very limited. The speech of the patients is slow, deliberate, and effortful, while function words and grammatical endings are often missing (Anderson et. al. 1999). This by the way is the form of aphasia my friend’s Uncle Peter suffered from. To give you an example what it was like talking to him, here is a video of a man with Broca’s aphasia talking to his speech therapist:

In case you are interested, there is a YouTube channel dedicated to the language development of Sarah Scott, a girl who had a stroke at 18, and from this day on has been suffering from Broca’s aphasia. Her speech learning is quite remarkable.

Typical for the other type Wernicke’s aphasia next to the damage in Wernicke’s area are severe difficulties with speech comprehension, while the speech is still fluent, and speed and intonation appear normal. Patients also tend to frequently use very detailed descriptions or newly created words. This becomes visible in this video of a male patient with Wernicke’s aphasia:

So we can note, the most important distinction between the two types of aphasia is that people suffering from Broca’s aphasia have great difficulty with producing speech but at the same time can understand mostly everything that is said to them. In contrast patients with Wernicke’s aphasia have great difficulties with understanding speech while they can still speak relatively fluently even if what they say does not contain a lot of information most of the time.

Getting your speech back
But here are the good news: aphasia can be treated and if you are lucky treated so well that a normal production and reception of speech are possible again. How? You can take part in a speech therapy to learn how to speak again. Before a speech therapy takes place patients are tested for the type of aphasia they are suffering from. For that they are spontaneously interviewed by a speech therapist so that their speech production and reception can be checked. During these interviews the patients for example have to repeat words, name items presented to them, write a text, read a given text out loud or speak spontaneously. After that the speech therapy begins.

How does a speech therapy work?
In a regular speech therapy a speech therapist comes several times a week to train language use and understanding with the aphasia patients. Here, they use several techniques and tools to help the patient learn. Uncle Peter for example had to do simple word finding tasks in fill-in-the-gap format, name items his therapist showed to him, and later learn how to hold a conversation. A speech therapy is most succesful when friends and family help the aphasia patients to regain their language abilities outside of the sessions. Therefore, 
UK connect (an organization who tries to educate society about aphasia and help those affected by it) made a handy information sheet with tips on how to handle everyday conversation with aphasia patients, which you can see here:

DAT – dementia of Alzheimer’s type
Another cause for a language disorder is Alzheimer’s. Alzheimer’s is a neurological disease from the family of dementia disorders in which brain tissue and nerve endings are dying and dissolving. This process cannot be undone and is not curable. It is a slow gradual process from mild to severe which affects intellectual as well as physical abilities. Also the effects on language are severe. Alzheimer’s influences language processing, language knowledge and communicative behavior in general. In the end stage patients may become mute (Hamilton 2008). The bad news here is, to this date scientists have not found a cause for Alzheimer’s and are still desperately researching to find ways to treat it, as more and more people are suffering from it when they get older. You can try speech therapy, but over the long run it will not stop Alzheimer’s from progressing, and the patients suffering from it will definitely sooner or later lose their capability of producing or understanding speech.

So what does this mean for us?
Ok, now that you have heard this fancy word “aphasia” and learned more about language disorders in general, you might ask yourself what you should do with this information and why it is important to know about it. Aphasia literally means “without speech”, because the patients suffering from aphasia (the Aphasics) cannot speak or understand what someone else says to them. Imagine not being able to understand what people around you are trying to tell you, or not having the possibility to talk to someone. Wouldn’t that be horrible?

What does the future look like?
In Germany alone there are over 85,000 people suffering from aphasia, and every year around 30,000 new cases occur. Scientists believe that over the course of the next years the number of cases will increase and more and more people will be affected by aphasia.
The numbers for Alzheimer’s are even worse. Right now in Germany there are over 1.3 million cases of Alzheimer’s noted and every year around 250,000 new people are starting to show the first symptoms. For 2050 it is estimated that 2.6 million people in Germany will be suffering from Alzheimer’s or another form of dementia.

This is why research in clinical linguistics is so important!
It enables people to get the help they need in order to reclaim their speech, and even more it is important, because scientific research might find ways to improve speech therapy, discover new prevention methods for speech disorders or perhaps even find a cure for Alzheimer’s. No matter what it is and no matter how trivial it might appear at first, every new thing scientist find out about aphasia, Alzheimer’s and other diseases, is helpful and good. The more we know about language and the brain and the ways to prevent and treat language disorders, the better.

A happy ending?
This way the lives of many people might get improved or even saved, and people have the chance to take part in everyday life again, just like my friend’s uncle Peter did. After a couple of years Uncle Peter had regained almost all of his language abilities, was able to successfully communicate with his family members and friends again, and even could go back to work. All of this thanks to speech therapy and the research in clinical linguistics behind that. So let’s be thankful for what science has found out so far and hopefully will find out in the future. 

Anderson, J.M. et al. 1999. “Conduction aphasia and the arcuate fasciculus: A reexamination of the Wernicke-Geschwind model.” Brain and Language 70, 1: 1-12.

Blank, S.C. et al. 2002. “Speech production: Wernicke, Broca and beyond.” Brain: a Journal of Neurology 12, 8: 1829-38.

Cummings, Louise 2008. Clinical Linguistics. Edinburgh: Edinburgh University Press.

Fava, Elisabetta (ed.) 2002. Clinical Linguistics: Theory and Applications in Speech Pathology and Therapy. Philadelphia: John Benjamins North America.

Hamilton, Heidi E. 2008. “Language and dementia: Sociolinguistic aspects.” Annual Review of Applied Linguistics 28: 91–110.

Steinberg, Danny 1993. An Introduction to Psycholinguistics. London: Longman.

Sources Images 
Featured image: Retrieved from

Motory and sensory regions of the cerebral cortex: Retrieved from OpenStax CollegeAnatomy & Physiology, Connexions Web site., Jun 19, 2013.

Ten top tips for talking with people with aphasia: Retrieved from

Sources Videos
Broca’s aphasia:

Wernicke’s aphasia:


by Lissi Müller and Joan Degener


Cite this article as: lissi&joan, "Language and the brain – what you need to know about speech disorders" [blog post]. In: Language Matters!, December 7, 2016,

(NOTE: If the authors have indicated their real names at the beginning or end of the post, please substitute the pseudonyms accordingly.)


Lissi and Joan both hold a B.A. from the University of Bonn in English Studies and Psychology respective English Studies and German Studies. In her Bachelor’s thesis Lissi investigated gender differences in using and perceiving sexist speech while Joan dealt with the question whether emojis have a reinforcing effect on the perception of politeness and irony in text messages. Both share their research interest in psycholinguistics and clinical linguistics. Lissi moreover is strongly interested in language and gender as well as neurolinguistics whereas another of Joan’s major interests is forensic linguistics. Both are currently enrolled in the “Applied Linguistics” M.A. program at the University of Bonn as first year students.

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  1. March 4, 2017

    […] seems to be a very challenging task: Terms and aspects like “Broca’s and Wernicke’s area”, “aphasia”, “prosodic features”, “discourse markers” or “ideological square” do not necessarily […]

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