Moving between two streaming apps often means adjusting the volume, even though the television has not changed. The difference comes from how each service measures loudness before delivery.
Loudness is measured, not left alone
Audio is not delivered at whatever level it happened to be mixed at. Each service measures the perceived loudness of a programme across its full duration and adjusts it toward a chosen target.
The measurement is weighted to approximate hearing rather than raw signal, so a quiet dialogue scene and a loud effects sequence contribute differently to the single number that results.
Different platforms picked different targets, and broadcast, cinema and music streaming picked different ones again. Nothing forces them to agree, so the mismatch survives every handoff.
Dynamic range is the real culprit
A cinematic mix deliberately places dialogue well below its explosions. That gap is the point in a treated room, and it is preserved when the mix is normalised as a whole.
Normalising the average leaves the gap intact. The result is dialogue that disappears under domestic noise and effects that are startling, which viewers experience as a volume problem rather than a range problem.
Music and much television are mixed far more tightly, with the quiet and loud passages closer together. Those sound consistent at any setting, which sharpens the contrast when a film follows.
The chain adds its own changes
Between the service and the room sit several devices that each may apply processing. A streaming box, a television and a soundbar can all be adjusting level independently of one another.
Television speakers compound this. Small drivers cannot reproduce low frequencies, so manufacturers apply processing that lifts the perceived body of the sound and shifts where dialogue sits within the mix.
Channel folding matters as much. A surround mix collapsed into two speakers has to fit a dedicated centre channel, which carries most dialogue, into the same space as everything else.
Why night modes exist
Most platforms and devices offer a compression setting under names like night mode or dialogue enhancement. These reduce the distance between the quietest and loudest passages after the fact.
The effect is deliberate flattening. Impact is lost, but dialogue rises above the room, which is usually the trade a domestic viewer would choose if asked directly.
What this means across a session
The mismatch is most obvious at transitions, because the ear adapts within a programme but has no time to adjust when an app changes or an advert break begins.
Adverts are prepared to broadcast conventions and often normalised separately, so they arrive at a level that feels aggressive against a film mixed with a wide range.