I sat through a presentation yesterday that had about 300 people in attendance. When you have that many people paying attention to every detail, you should be on top of your game and ensure that every aspect of your presentation is as perfect as it can be. That includes minor details as well. One detail overlooked was that the technician running the slide deck in this case was that the volume on the laptop had to be adjusted several times throughout the presentation. When you press the volume up/down button to adjust the volume, there is a "beep" generated by the system. Ordinarily, that beep is great because it gives you a real-time sense of where the volume level is set to. However, in front of a large audience, it can be distracting (and awkward).
The temporarily disable the beeps while you adjust the volume, simply hold down the Shift key while pressing the volume up/down keys. Simple and effective.
The video below shows this tip in action: