Link Error "Voice-Processing I/O Audio Unit Properties"

I'm looking for information on the audio unit using this site (https://developer.apple.com/library/content/documentation/MusicAudio/Conceptual/AudioUnitHostingGuide_iOS/UsingSpecificAudioUnits/UsingSpecificAudioUnits.html.)

However, the link that describes specific properties available for this audio unit, "Voice-Processing I/O Audio Unit Properties" is not working.

So, are there other documents that describe it?

Please tell me the information about it.


Best regards,

S. Tanaka