A Strudel voice must be tagged `.analyze('hydra')` to contribute to the FFT — an untagged voice is inaudible to the visuals even if loud in the speakers

The analyser only sees voices explicitly tagged with .analyze('hydra'). An untagged voice contributes zero to a.fft, so reactive visuals will not respond to it no matter how loud it is. To make visuals react to the whole mix, every $: voice (or a summing bus) must carry the tag. The seed file music/hello.strudel tags every voice by default. When building new patterns, omitting the tag on a new voice is the most common reason a working reactive sketch stops reacting to new content.

Examples

$: s('bd').analyze('hydra') — the kick contributes to FFT. $: s('hh') — the hat is audible but invisible to Hydra; a.fft ignores it.

Assessment

A performer adds a new hi-hat pattern in Strudel but the Hydra highs band stays flat. What is the most likely cause and how should they fix it?