As iPhone and iPad owners know, Apple maps specific output levels to its physical volume controls, in some ways mimicking a stepped attenuator. While not as smooth as a potentiometer style knob, the presets are good enough to home in on a desired loudness level.
Changing volume on AirPods via Siri works in a similar fashion, but instead of buttons users tell the virtual assistant to "lower volume" or "turn up the volume" with their voice. The process feels vague in comparison to the physical controls on iPhone, perhaps in part due to the lack instant onscreen GUI feedback.
Further confusing matters, iPhone's volume controls raise and lower output in 6 percent chunks, while Siri makes changes of 12 to 13 percent when performing the same operation. The method avoids repeated commands, but makes it difficult to arrive on a specific volume.(The article continues...)