Amazon has introduced a new feature to Prime Video called Dialogue Boost. It’s intended to isolate dialogue and make it louder relative to other sounds in streaming videos on the service.

Amazon describes how it works in a blog post:

Dialogue Boost analyzes the original audio in a movie or series and intelligently identifies points where dialogue may be hard to hear above background music and effects. Then, speech patterns are isolated and audio is enhanced to make the dialogue clearer. This AI-based approach delivers a targeted enhancement to portions of spoken dialogue, instead of a general amplification at the center channel in a home theater system.

Not all content will be eligible for the dialogue boost feature, though—at least not yet. Amazon says it “has initially launched on select Amazon Originals worldwide” like The Marvelous Mrs. Maisel and The Big Sick.

While this is partly an accessibility feature for people who are hard of hearing, Amazon is also responding to a widespread complaint among viewers.

A 2022 survey found that 50 percent of 1,260 American viewers “watch content with subtitles most of the time,” many of them citing “muddled audio” and saying that it’s more difficult to understand dialogue in movies and TV shows than it used to be.

The dialogue problem

There’s no one simple reason for this development. It involves several factors, but many of them could reasonably be categorized under a “fragmented viewer experience” banner.

Decades ago, most TVs or home theater speakers had similar audio capabilities. However, the range of devices used—from built-in speakers in cheap TVs and laptops to high-end Dolby Atmos surround-sound systems with AI-optimized sound fields and everything in between—has grown. Additionally, TV manufacturers introduce a wide variety of proprietary technologies and configurations that they can try to use to differentiate their products in marketing materials, changing the way the same content sounds on nearly every device.

All of that means that professionals who master and encode audio for distribution on streaming networks have their work cut out for them. Some shows prioritize making sure it sounds good for the highest-end setups, but the comparative lack of dynamic range in cheaper speakers can leave owners of lesser systems with muddled audio. But even if a (futile) effort is made to encode the audio for the widest viewership possible, the devices are still so fragmented that it may be impossible to ensure a quality experience for everyone.

There are other factors, too, of course. More theatrical styles of TV acting that were popular in the ’70s, ’80s, and ’90s have given way to a subtler, more realistic delivery that was previously the realm of art films. While those deliveries played well in movie theaters with robust sound systems, they don’t always work as well on $200 TVs. Streaming bitrates and related audio quality can also vary from household to household.

It’s a similar set of underlying problems to TV shows appearing too dark for some viewers. Many of us remember the final-season Game of Thrones episode that had viewers squinting in vain to see what was happening. Film techniques playing on small screens with limited contrast, peak brightness, and dynamic range were all at play there—though HBO Go and HBO Now’s then-subpar resolution and bitrate were a particularly big issue in that specific case.

Anyway, back to audio: Some streaming boxes or audio systems—like the Apple TV 4K or Sonos’ home theater offerings—offer built-in dialogue-boosting features, but not everyone uses those devices. Amazon’s new feature should, in theory, work on anything, even if it doesn’t already have support for dialogue boosting.

The company hasn’t announced when the feature will expand to more content. But we wouldn’t be surprised to see rapid expansion—not just from Amazon, but from other streamers offering similar features, too.