Generally speaking, once you have reached a competent level of upper intermediate (B2 CEFR) or above, you probably have enough vocabulary to cope with most situations. You have studied the language for years and will have picked up a lot of the English lexicon, but it needs practice. If you are using English irregularly, or hardly ever speaking it out loud, the language may start to become passive knowledge, rather than active knowledge. When it is stored in your brain you will recognise the words or phrases and understand what is being said, or the text you are reading, you may also be able to repeat it once you have heard it, but that particular word or phrase might not be your first choice when speaking. In order for vocabulary to be part of your active knowledge, regularly usage is key.
Having studied grammar for many years at school, your awareness of the different tenses, and sentence structures is probably quite good. You do not necessarily get it accurate 100% of the time, but you are understood more often than not and any mistakes made are inconsequential to the communication. Being precise in your use of grammar can be helpful to make sure someone knows whether something happened recently, or a long time ago, when you were a child, alternatively if you have already made plans for the weekend, or you are just coming up with an idea now. But these things can all be ironed out with a couple of questions, some clarifying information, or a little more context.
However, once you have a basic understanding of both vocabulary and grammar, in truth, it only becomes beneficial to expand on that knowledge when you can really use it to your full advantage. You have an instinctual use of pronunciation based on your passive learning from listening to your teachers, classroom audio files, TV series and films. Having said that, because it was never taught, you are probably not conscious about the decisions you make as to how you say the words within a sentence when speaking English. Is that really a problem? If you simply want to use your English while travelling on holiday, then honestly, no; it is not a problem. Although if you would like to be able to use it competently at work in order to support your career and help you reach your goals, then being able to use pronunciation to influence how others understand exactly what you have said could be hugely beneficial. Because if your intonation implies that you're bored with the situation or not as keen as your words might suggest, not many people will ask a follow up question to check that is what you really meant, as they might be more willing to do with grammar or vocabulary.
What are the other benefits to understanding more about pronunciation, you may ask; let's have a look.
1. You no longer have to rely on subtitles
When you learn more about how English pronunciation works, for example, how words join together, how when certain sounds are together they can morph into different sounds and how emphasis within a phrase can influence the meaning of the sentence; even if you do not actively use these yourself, you will be able to understand other proficient speakers more easily, which will enable you to communicate with fewer misunderstandings. You will even be able to confidently watch videos without subtitles and also listen to audiobooks or podcasts in English without worrying about missing information. This will start the process of increasing your self-confidence.
2. You know you belong
As your self-confidence grows, while you improve your listening skills, you will become more aware of the nuances of the English language and you will be able to pick up on more subtle messages from other speakers. Because you understand what people are really saying, you can respond appropriately and you will no longer feel like an imposter. You will know you belong in your team, because you can assuredly contribute to projects, meetings and presentations, in addition to the small talk in the corridors, gaining more self-respect as well as approval from your colleagues.
3. You take control of your life
As you start to implement your knowledge into your own spoken English, your self-belief will soar as you realise your message is coming across exactly as you meant it to and with this you will stand taller when you speak, with better posture, you will smile more as you relax into your communication. With your more natural body language, you will be able to develop better personal relationships with colleagues, acquaintances and strangers alike! All of which will contribute to a higher self-esteem, allowing you to take control of your life in ways you had not even imagined. For example, you will put yourself forward for that promotion you have been wanting, or you will take a leap of faith and go for that job you have dreamt of for years.
Now that you understand the benefits of improving your pronunciation, the only question left to answer is: how? That is simple: there are plenty of ways to learn more about pronunciation; there are hundreds of YouTube videos, online courses and good language teachers who understand the importance of pronunciation.
If you would like more support from me, please get in touch; you can find more details of my current courses here: Pronunciation Courses | Excellence in English Education