I'm working on a project that requires detecting frequencies around 18kHz using the WebAudio API on mobile. However, the frequency bins I get back never seem to be able to detect anything over around 10kHz, but I know my phone can detect higher frequencies by using other spectral analyzing apps. How can I solve this or work around it?
I'm presuming you're using live input. You need to disable all the automatic filtering; take a look at How to disable Web-Audio analyzer filtering high frequencies.