Question: Watching various COVID-related briefings, I notice there is always a sign language interpreter. This is clearly necessary, yet thinking about all the conferences I've attended in the past, literally none of them have had a sign language interpreter.

How do conferences work for deaf scientists? Do deaf scientists simply not attend conferences? If so, how does one even work in fields such as computer science where conferences are an integral part of the academic experience?

Answer: 
In what was a very large astronomy conference I have seen a sign language interpreter (actually they had two, who round swap every few minutes during the talk) in certain sessions (presumably going to the sessions which the deaf scientist(s) was attending). I haven't seen this at other conferences, but whether that is because of their smaller sizes or because deaf scientists didn't attend I don't know.
In spite of what Anonymous Physicist says, conference can work for deaf scientists. This is the case in my own area of work, digital accessibility.

There are two main methods to make conferences accessible for deaf attendants:

1. **Sign language interpretation**: this means that a sign language interpreter translates the spoken words into sign language. If the conference is a local or national event, the sign language interpreter will translate into the national sign language, e.g. American Sign Language (ASL), British Sign Language (unrelated to ASL), German Sign Language, etc. However, if the conference is an international event, there won't be sign language interpreters for each of the nationalities represented in the audience. In that case, sign language interpreters will translate into [International Sign](https://en.wikipedia.org/wiki/International_Sign). Sing language interpreters take turns every 20-30 minutes. It is also helpful if they know in advance what the talk will be about, so they can prepare for it.
2. **Live transcription into text**: the talk is transcribed live and the transcription is displayed on a large screen at the front of the conference room. The transcriber can be physically at the conference or connected remotely. The transcription is in the same language as the talk.

For congenitally deaf persons, sign language translation is preferable, since that represents translation into their native language (except if the translation is into International Sign), whereas written language is essentially a foreign language.

Research into sign language avatars has been ongoing for quite some time, but I have never seen them in action at conferences.

The above is about deaf scientists in the audience. What about deaf scientists giving a talk?

In 19 years of research in accessibility, I have seen this only once. It was a congenitally deaf researcher from Finland who gave a talk in English. His pronunciation was only marginally harder to understand than that of many other non-native speakers of English, i.e. something one could get used to within minutes. The only issue was that he did not know how loud he was talking, so he asked he wasn't talking to loud. After feedback from the audience, he started talking less loudly.

(The conferences I am referring to include [ICCHP / International Conference on Computers Helping People with Special Needs](https://www.icchp.org/), where translation was into International Sign, the e-Accessibility Forums in Paris (transcription), events organised by the Swedish organisation Funka/FunkaNu (transcription) and conferences organised by EU-funded projects in the domain of digital accessibility.)