---
id: LSN-0010
ticket: legacy-runtime-learn-import
title: Audio Mental Model
created: 2026-03-27
tags: [migration, tech-debt]
---

# Audio Mental Model

Status: pedagogical
Companion spec: [`../specs/05-audio-peripheral.md`](../../specs/05-audio-peripheral.md)

The right mental model for audio in PROMETEU is an active peripheral with a budget, not "automatic sound".

## Philosophy

Sound:

- consumes time;
- consumes memory;
- uses finite channels;
- depends on explicit commands.

That brings PROMETEU closer to classic consoles and arcades where the game "talks" to an audio block with its own rules.

## Audio CPU Metaphor

A useful metaphor is:

```text
[Game CPU] -> sends commands at 60 Hz -> [AUDIO Peripheral]
                                         |
                                         v
                                   Voices + Mixer
                                         |
                                         v
                                     PCM Output
```

This metaphor does not require a dedicated thread. It only separates responsibilities:

- the machine defines the logical model;
- the host decides how to deliver continuous buffers;
- the game speaks in commands, not direct backend manipulation.

## Good Habits

- reuse samples;
- limit simultaneous voices;
- treat sound as an intentional event;
- separate music and effects;
- avoid triggering the same sound every frame.

## Historical Direction

The main influences here are:

- NES, for the clarity of limited channels;
- SNES, for sample playback and mixing;
- CPS-2 and Neo Geo, for the feeling of headroom and sample presence.

PROMETEU abstracts those references. It does not try to reproduce any of those systems literally.