Async vs Sync Communication

We can divide communication into two channels:
Synchronous (Sync) - all parties are actively taking part in the conversation right now. For example, physical meetings or a video call
Asynchronous (Async) - one party writes or records a message and has to wait for responses for an indefinite amount of time. For example, sending an email or posting on a discussion board.
Conversations on sync channels are usually recorded only in the heads of the participants where async channels are a more permanent medium.
Chat applications are a bit of a grey area; they allow for synchronous communication, but often you have to wait for a response. Because of the inherently fleeting nature of real-time chats, I consider them to be synchronous.

In the workplace, often conversations will revolve around making a decision - for instance, choosing between various options. These conversations, ideally, can be divided into three stages.
Each stage will involve the usage of both synchronous and asynchronous channels. They are:

  1. Initialisation
  2. Discussion
  3. Decision

Initialisation

This stage starts with someone writing down a proposal, an introduction to the subject, and it may also include some initial research done by the person writing it. It can be a detailed post, or it can be simply an email invitation with a short description of the subject. Follow up with brainstorming to gather opinions; it’s not a time for decisions yet - we are just stimulating the conversation and collecting ideas. After a brainstorming session, one person writes a follow-up post summarising what you have discussed and all the ideas mentioned, including rejected ideas as well for completeness. Someone good at taking notes will be very helpful here.
We have here both synchronous and asynchronous communication.

Discussion

Now people have been familiarised with the subject. It is time to digest it. I’m sure everyone has experienced clarity after a night of sleep - that is why this stage may take a few days or even weeks, assuming there is no particular time pressure. At this stage, people should mostly use async channels to communicate with the whole group. Sync channels should be seen as supplementary to be used when you want to avoid spamming the async channel with the back and forth of short questions and answers. I recommend adding a summary of such conversations in the async channel later.
Again, we employed both synchronous and asynchronous channels.

Decision

When enough time has passed - maybe because there is a deadline, or the discussion is slowing down, or agreement seems to have been reached - we head back to a meeting room to make the decision. Ideally, there should be no more new ideas introduced at this point. In terms of how you pick the winning idea that is another subject. It could be a democratic vote, a manager/leader decision, or dice roll. After the meeting, you write a summary.
Once more, both synchronous and asynchronous communication is involved here.

How to improve

Writing and speaking with clarity can both be difficult, but they are vital skills and need to be worked on, no excuses here. But if you are bad at either and finding it hard to improve by yourself, then try to find someone good at it and work together.

Writing

If you are bad at writing, find someone who does it well. Write a draft with what you want to say, and ask them to review it, improve it based on their feedback. Rinse, repeat until it is ready to be shown to a broader audience.

Speaking

If you are bad at speaking, then try to write down all the points you want to say first - remember it is ok to read notes in the meetings. You can practice speaking by finding someone who likes to have small debates and discuss opinions with them in a one-on-one setting, so you don’t stress because of group pressure.

My Experience

For me, the writing was always my weaker point of the two. In school and university, I always struggled with reaching the required word count. Today I know that they taught me writing the wrong way. It is not about the word count. If you know what you want to say the words will come by themselves. Write a draft first as if you were talking, then review and improve it. There are a lot of books, blogs, and courses that share tips on how to improve your writing. One point they all agree on is this: write something, anything, and improve later.
My speaking skills improved thanks to a volunteering organisation I was involved with in high school. During my university years, I had a job in customer service that helped a lot as well. When I started working as a software engineer, my problem was lack of confidence and impostor syndrome. I was questioning myself in my mind all the time, which made it hard to take part in conversations. That one is hard to solve, and I don’t have any suggestions here. I overcame it at least partially thanks to my team members at Football Radar showing recognition for my skills.

Conclusions

It is not a case of async versus sync communication. As with many things, it is not one or the other. Each approach has its use cases, and they complement each other. Use them together at the right time to derive the most benefit.