Source Priority, Audio Focus, And Ducking

Canonical Definition

Source priority is the policy that decides which audio context may play, pause, mix, duck, mute, or replace another. Audio focus is the software or vehicle-control mechanism used to request and manage that priority. Ducking is a controlled temporary gain reduction, not a universal fixed attenuation.

Different Interrupt Behaviors

Behavior	Result	Typical risk
pause	lower-priority audio stops	slow or incorrect resume
replace	new context takes the route	wrong source restored afterward
duck	lower-priority audio continues at reduced level	spoken content becomes unintelligible
mix	contexts play together	headroom loss, duplication, or phase interaction
mute	selected route or group is silenced	safety or alert path is accidentally included

Contexts To Map

music, podcasts, audiobooks, and radio
navigation guidance
phone and communication audio
voice assistant and speech recognition
parking, collision, restraint, emergency, and other safety sounds
OEM chimes, active sound, ANC, and multi-zone audio

Who Owns The Decision?

app or phone audio session
→ projection framework or head unit
→ vehicle audio service or factory amplifier
→ integration interface or DSP routing
→ physical output zones

More than one stage can act on the same event. A duplicated prompt can result when a factory path and an aftermarket mixer both reproduce it.

Ducking Must Be Measured

Record attenuation, attack, release, output route, and restored state. Music may remain intelligible under a prompt while speech-on-speech material may need to pause. The correct policy depends on context, vehicle architecture, and safety requirements.

Verification

List every audio context and output zone.
Identify which stage grants priority and changes level or routing.
Measure pause, replace, duck, mix, mute, attack, release, and restored volume.
Test fader, balance, user mute, source change, calls, prompts, and vehicle safety states.
Repeat after communication loss, reconnect, key cycle, and sleep.