Zoom's audio settings read like they were named by a committee that wasn't allowed to talk to users. Here's what each one actually does to your signal on a Mac, and the settings that fix the complaints people usually blame on their microphone.
Microphone selection: the dropdown that overrides everything
Zoom keeps its own input selection, independent of System Settings. Change your Mac's default input and Zoom keeps using whatever its dropdown says — the override chain works app-first. There's also a "Same as System" option, which follows the system default and inherits its problem: macOS re-picks the default when devices come and go, so "Same as System" means "whatever got plugged in last" more often than people expect. Selecting one specific device is more predictable — and selecting one specific virtual device that manages the physical mics behind it is how you stop thinking about this dropdown entirely.
Automatically adjust microphone volume
Zoom slowly rides your input gain toward a target level. For a mic at a fixed distance it's harmless. For a speaker who moves, it's always a step behind: you lean back, your level drops, Zoom cranks gain — and pumps up your room noise with it — then you lean in and the first seconds are hot. If your voice level swings because your distance swings, gain-riding treats the symptom. Fix the distance problem (placement, or multi-mic coverage) and this setting stops mattering either way.
Background noise suppression: Auto, Low, Medium, High
This is Zoom's own noise reduction, applied before your voice leaves your Mac. High is aggressive: great against a vacuum cleaner, but it can chew the quiet onsets of speech and add a processed quality. Low preserves the most natural voice and is the right choice for a reasonably quiet room. Auto floats in between. If teammates say you sound "underwater" or your first syllables clip off after silence, drop this to Low before blaming the mic.
Original sound for musicians
The most misunderstood toggle in Zoom. It disables Zoom's noise suppression, echo cancellation adjustments, and high-pass filtering, and optionally enables stereo and higher-quality codecs. If you have a clean signal chain — a good mic, close placement, quiet room, or processing you've chosen yourself — Original sound is how you let that quality through instead of having Zoom flatten it. If you're on a laptop mic in a kitchen, leave it off; the processing is earning its keep.
The settings that can't help
No Zoom setting fixes the two most common Mac audio complaints. A voice that fades when you turn to another monitor is an off-axis and distance problem at the microphone (measured here). And hollow, roomy sound is a mic-too-far problem that suppression can only smear further (the echo-and-reverb guide). Both are input problems, and Zoom sits downstream of your input.
The upstream fix: give Zoom one stable input that's already right. SoundMesh presents a single virtual microphone backed by every mic you own, keeps your voice on whichever one hears you best as you move, and never changes identity when devices reconnect. Set Zoom's dropdown to it once, put suppression on Low, and the settings panel becomes a place you used to visit.