How to address individual audiences with diverse members (hint: simple structure, even if the detail
As I discussed on other last tips, individual audience members will vary in their expertise and there will be uncertainty about who will actually come to your talk. How do you manage this?
The first step is to identify the least expert person you care about reaching. It is probably impossible to simultaneously address someone in your subspecialty and a lay person, but you can still meet the needs of a fairly broad spectrum. Prior to the talk, identify the range of people you want to reach and the least expert part of that range. For example, if you are giving a job talk, the range may span the individuals in your subspecialty to the department chair, who hasn't been in the lab in 15 years and doesn't know your specific area. You've decided ahead of time that you will not try to reach a pure lay person.
So in the above example, draft a simple narrative that the least expert target audience (department chair in the above example) can understand. Work out the language that allows you to explain that narrative to the department chair in a short amount of time. You don't need to include actual data in the narrative, but you do want to transmit the conceptual points.
Now you can add complexity and specificity that only experts can understand. But you are adding it to a structure and narrative that a broader audience understands. It is OK if the less expert audience members doesn't understand the methods underlying a slide or two because your talk is organized around a narrative they can understand. Continually connect detailed messages targeted toward the experts to the points in the narrative you've created for the generalists.