Technical tips to improve the quality of video calls
The physical environment
One of the most important factors for a good-quality video is finding a quiet room, where there are no noises that can disturb you or the person you talk to, and you don't have to be worrying about disturbing anyone either.
Your audio equipment
Headsets with two headphones and a mic is at the end of a boom (an attached stick, so the mic is closer to the mouth) tend to be better because they are closer to your mouth and tend to deliberately be more sensitive in the direction of your mouth and less sensitive in other directions where noise may come from. However, position the boom so you don't blow air on it, or else it can create very loud PFFFF noises.
Mics without the boom tend to have to do a lot of signal processing to filter out room noise, and the result is often worse.
Headsets with cable offer in general better quality than Bluetooth ones (if everything else is more or less equal quality). Two main reasons:
They are immune to interference in the electromagnetic spectrum.
There's a much smaller delay (latency) for the audio (usually zero, while that's impossible for Bluetooth).
And they are actually cheaper.
If you already have a Bluetooth pair, you can use it, but if you're considering buying a set and you're planning to do a lot of video calls, you may want to consider one with cable. Of course, Bluetooth is more convenient if you are just listening to music. I personally have a Bluetooth pair for music, but for videocalls I use a cable one.
Loudspeakers and standalone mics can sometimes work, but it can sometimes create a feedback loop: the sound of the speakers is caught by the mic, so the other person hears what they said half a second later. When this happens, the conversation becomes very difficult. It happens much less often with good headsets.
Your WiFi
Bad Wifi is a frequent cause for difficult video calls. Sometimes it's difficult to solve, but the most basic recommendation is to stay as close as possible to the WiFi hotspot (a box that sometimes, but not always, has antennas). Some walls have metal inside, which creates a barrier. There may also be interference from other devices outside the network, or too many devices connected to the same hotspot. If you have issues, the best advice that's not technically very complex is trying to move to the same room where the hotspot is. Sometimes, installing a repeater can help.
Ethernet cable is much better than WiFi (faster, no interferences, no delays/latency), but nowadays WiFi has become much more common because it is more convenient. However, if you have the possibility to use Ethernet cable, like for instance you have the Internet router nearby and there's an easy path for the cable, I recommend it. Since my work involves a lot of video calls, I use it on my end.
Your Internet connection
Your Internet connection isn't the same as your WiFi connection. It's the connection between your WiFi hotspot and the machines from your ISP (Internet Service Provicder: the company you normally pay for the Internet). These are different types of Internet connection, from best to worst:
Optical fibre: in most situations, this is the very best. It's what I use.
Coaxial cable / "Cable Internet" (a thick cable with a rigid copper wire in the middle). Generally good, but depends on how it's installed.
4G/5G. It can vary a lot depending on many circumstances, it could be in second or third place. Most often, when using 4G/5G, you skip the WiFi step, since it's already wireless.
4G/5G+WiFi. In some cases, however, one can have a 4G/5G connection behind a WiFi connection.
For instance, if you use your phone as a WiFi hostspot, there's two wireless jumps one after another. Although it can be convenient in some situations, I don't recommend it for video calls because the less wireless jumps, the better. In this situation, there's always a way to connect the phone to the PC with a USB or lightning cable, so you skip one wireless jump.
Another situation where this happens is if you live in a rural area, and you have a central device in your home that uses 4G/5G to provide Internet to your whole home, and distributes it over WiFi to different devices. In some of these cases, it can still be possible to skip one wireless jump if you can use an ethernet cable to connect your computer to this device.
Stuff such as Starlink is kinda mid-tier in terms of latency today, and could be placed here.
ADSL/DSL and other things that go over old twisted-pair telephone systems.
You can use a service such as this one to test your Internet connection. For a video call, what matters the most is not the download or upload in Mbps, but the smaller and more inconspicuous numbers with "ms" (milliseconds) behind. The lower, the better, since it's the time data takes to arrive from/to your computer to/from a computer somewhere on the Internet. That particular test gives you three numbers, but a simple rule is:
All less than 100 ms: Very good
100-200ms: Okay
More than 200ms: Here problems start to be noticeable, because people will start to talk over each other.
You can use the website to test different places within a building, and different workplaces. Results for a given place may vary depending on circumstances.
The result the test gives you us the latency of the internet connection + the latency of the WiFi, since one is behind the other. There are ways to measure them independently in order to pinpoint where a problem is, but they are more complicated. You can ask me if you're interested.
Software
Many modern video software has a built-in AI noise cancellation systems enabled by default. It's designed to block sounds like flowing water or something popping in the background. The problem is that due to this, they can end up blocking some parts of what one says, such as f's and p's, which sound very similar to these background noises. Some systems look around the sound, and if it's followed by a vowel, they guess it's an actual f or p and let it through, but this requires introducing a delay for the system to be able to make this decision.
Overall, it is a necessary evil if you do actually have background noises, but if you're in a silent room, deactivating the noise cancellation can improve the quality.
Avoid many apps or browser tabs running in the background, because some of them can consume CPU and make the computer slow, and that can affect the audio or the video.
Useful interactive productivity tools
For many kinds of lessons or meetings, a collaborative document system is best. Microsoft Office and Google Docs offer this. I personally use Google Docs, especially for language teaching. One can for instance make comments about certain parts of a text, make suggestions that are highlighted in a different colour, seamlessly connect with other materials in other documents, etc. To make full use of these features, you must have a Gmail address.
For other subjects, such as mathematics, an interactive whiteboard can be very useful. I use tldraw.com. I have an electronic pen, but I know most students don't. However, if you have a laptop with a pen, or a drawing tablet, it's a good opportunity to use it.
If you have any questions, you can write to me at jacobo@rouces.com.