Interesting comment by Deborah Meaden on a recent episode of Dragons Den (UK S8:E2 I think). The invention was a more compact variant on the megaphone, consisting of a small microphone/amp section and a separate speaker section, with the idea that the speaker could be held up above the crowd. The comment was that, whilst effective in the core function (projecting the voice), the megaphone also has an important visual function—the person directing a crowd can readily be identified because they are holding a megaphone-shaped object, not just because they are speaking. Makes an interesting comment on the notions of form and function.