Digital and social media have grown exponentially to become highly influential spheres of public communication -- increasingly crowded, contested, and corrupted, and increasingly in need of scholarly engagement. As public debate is conducted more through social and digital media, alternative metrics ('altmetrics') that are generated from social and digital media platforms become important as indicators of impact and engagement. We review the growth of amplifier platforms and the academic and contextual reasons for their growth. Amplifier platforms are defined to distinguish them from traditional media outlets (where the scholarly voice is mediated through and 'gatekept' by journalists, whose editors retain final control), personal blogs (very few of which can be maintained over time) and from social media platforms (where the scholarly voice is accorded no presumptive standing). A significant range of amplifier platforms is canvassed while acknowledging that in Australia, the amplifier platform "The Conversation" plays a central role.