Godot Audio System

Master (always exists)
├── Music          → volume, effects for background music
├── SFX            → volume, effects for sound effects
│   ├── Footsteps  → sub-bus for fine-tuning
│   └── Weapons    → sub-bus for fine-tuning
└── UI             → volume for menu sounds

extends Node2D

@onready var sfx_player: AudioStreamPlayer2D = $AudioStreamPlayer2D
@onready var music_player: AudioStreamPlayer = $MusicPlayer

func _ready() -> void:
    # Play background music (looping is set on the AudioStream resource)
    music_player.play()

func play_jump_sound() -> void:
    sfx_player.stream = preload("res://audio/sfx/jump.wav")
    sfx_player.play()

using Godot;

public partial class AudioExample : Node2D
{
    private AudioStreamPlayer2D _sfxPlayer;
    private AudioStreamPlayer _musicPlayer;

    public override void _Ready()
    {
        _sfxPlayer = GetNode<AudioStreamPlayer2D>("AudioStreamPlayer2D");
        _musicPlayer = GetNode<AudioStreamPlayer>("MusicPlayer");
        _musicPlayer.Play();
    }

    public void PlayJumpSound()
    {
        _sfxPlayer.Stream = GD.Load<AudioStream>("res://audio/sfx/jump.wav");
        _sfxPlayer.Play();
    }
}

# Get bus index by name
var bus_index: int = AudioServer.get_bus_index("SFX")

# Set volume in dB directly
AudioServer.set_bus_volume_db(bus_index, -6.0)  # -6 dB = ~50% perceived volume

# Convert linear (0.0–1.0) to dB — use for UI sliders
func set_bus_volume_linear(bus_name: String, linear: float) -> void:
    var index := AudioServer.get_bus_index(bus_name)
    AudioServer.set_bus_volume_db(index, linear_to_db(linear))

# Mute / unmute a bus
AudioServer.set_bus_mute(bus_index, true)

# Read current volume as linear (for displaying on a slider)
func get_bus_volume_linear(bus_name: String) -> float:
    var index := AudioServer.get_bus_index(bus_name)
    return db_to_linear(AudioServer.get_bus_volume_db(index))

int busIndex = AudioServer.GetBusIndex("SFX");

// Set volume in dB
AudioServer.SetBusVolumeDb(busIndex, -6.0f);

// Linear to dB conversion for UI sliders
public void SetBusVolumeLinear(string busName, float linear)
{
    int index = AudioServer.GetBusIndex(busName);
    AudioServer.SetBusVolumeDb(index, Mathf.LinearToDb(linear));
}

// Mute / unmute
AudioServer.SetBusMute(busIndex, true);

// Read current volume as linear
public float GetBusVolumeLinear(string busName)
{
    int index = AudioServer.GetBusIndex(busName);
    return Mathf.DbToLinear(AudioServer.GetBusVolumeDb(index));
}

# Enable/disable an effect on a bus at runtime
var bus_index := AudioServer.get_bus_index("SFX")
var effect_index := 0  # First effect on the bus
AudioServer.set_bus_effect_enabled(bus_index, effect_index, true)

# Apply low-pass filter for "underwater" feel
func set_underwater(enabled: bool) -> void:
    var index := AudioServer.get_bus_index("SFX")
    # Assumes a LowPassFilter is the first effect on the SFX bus
    AudioServer.set_bus_effect_enabled(index, 0, enabled)

Enemy (CharacterBody2D)
├── Sprite2D
└── AudioStreamPlayer2D   ← positioned at enemy's location
    bus = "SFX"
    max_distance = 1000.0
    attenuation = 1.0

# Make a specific camera the audio listener
# 2D: add AudioListener2D as child of Camera2D, call make_current()
# 3D: add AudioListener3D as child of Camera3D, call make_current()

# By default, the current Camera2D/3D acts as the listener.
# Only add an explicit AudioListener if you need a different listening position.

// 2D spatial player
public partial class Footsteps : AudioStreamPlayer2D
{
    public override void _Ready()
    {
        Bus = "SFX";
        MaxDistance = 1000.0f;     // Pixels at which volume reaches zero
        Attenuation = 1.0f;         // Linear falloff (higher = sharper)
        MaxPolyphony = 4;           // Allow overlapping footstep sounds
    }

    public void PlayStep() => Play();
}

// 3D spatial player
public partial class EngineHum : AudioStreamPlayer3D
{
    public override void _Ready()
    {
        Bus = "SFX";
        UnitSize = 4.0f;            // Meters at which volume is 0 dB
        MaxDistance = 50.0f;
        AttenuationModel = AttenuationModelEnum.InverseDistance;
    }
}

// Custom listener — overrides the default Camera2D / Camera3D listener.
public partial class FollowCamListener : AudioListener3D
{
    public override void _Ready() => MakeCurrent();
}