The web-audio pipeline is like a chain of audio-plugins, loaded into Javascript, which does custom audio processing. This includes the low-cut filters, limiting, compression, audio-visualizers, active-speaker, director-side gain and mute control, and more.
This audio pipeline can start to have problems though if the CPU is overloaded. This can result in odd issues, including clicking. This pipeline is disabled by default in scenes, but it's usually enabled by default for most guest types.