An elevator speech is a 30–60 second summary of your research interests, main findings, and their importance to society. It's a good way to introduce yourself and your work, whether it's to professional colleagues at a conference or a job interview or just explaining your work to your neighbors and new acquaintances.
When composing an elevator talk for the first time, writing it out will help you organize your thoughts and identify areas for improvement.
Focus on the most important aspects of your work. Remember you have a time limit, and you need to use a normal rate of speech. "Differentiate what you do from how you do it….Start with the big picture of your research, give it context, and then proceed to the main points you want to convey1."
Even if you're speaking to someone of similar training and familiarity with the field, showing an ability to communicate clearly in plain language is an admirable trait.
Once you have a good written draft, adapt it for spoken language—account for natural rates of speech, including pauses for effect or clarity. Consider how voice and body language can convey your message.
Now practice your speech orally—first to yourself, and then to friends and peers. Convey the interest you have in your work. Use and be open to questions. Adapt your talk based on other's feedback, which may include questions about the subject of your talk.
A good elevator speech will pique the interest of the listener. What you say can (and should!) give rise to specific questions about your background or findings. Anticipate those questions and prepare concise answers to them. Giving your speech a few times will help you identify what those questions might be. If you consistently get the same questions, you might want to incorporate the answer into future versions of your talk.
An elevator speech is a means to an end: to share what's important about your work and to start a conversation.
Because you'll be talking with more than one group of people during your career, develop a few versions of your speech and know which one will resonate best with your audience (one version might emphasize the social benefit of your work, another the financial viability of your current research, a third focusing on practical value for future work).