In this article I investigate online sound mapping practices, taking cartophony – the coming together of cartographic and sonic activities – as an important contribution to emerging ways of thinking and practicing mapping. I first develop a typology of approaches to cartophony, before moving on to reveal the normative tendencies of online combinations of sound and mapping through an analysis of three platforms: Freesound; audioBoom; and Radio Aporee. Showing how in different ways each of these platforms supports an approach to sound mapping that favours pinning high fidelity, indexical audio-recordings to a seemingly neutral base layer, I question what is glossed over through this approach, while also considering how visual and sound-based strategies for communicating about places illuminate and resonate with one another. Discussing some more experimental online sound maps, I highlight the value of such projects in their current form, and argue for the continued expansion of cartophonic practice.