Voyager — sound theme for KDE Plasma

A signal that has been travelling for a very long time

A complete, freedesktop Sound Theme specification compliant sound theme for KDE Plasma 6 (and any other desktop that honours the spec). 61 cues, all of them synthesised from scratch — no sample library, no third-party audio, no attribution burden. The whole theme is reproducible from the script in tools/.

kde-sound-theme-voyager/
├── Voyager/
│   ├── index.theme          # [Sound Theme] + [stereo] OutputProfile
│   └── stereo/              # 61 × Ogg Vorbis 48 kHz stereo
├── tools/
│   ├── gen_sounds.py        # the synthesis engine (reproducible)
│   ├── verify_theme.py      # spec + audio + KDE coverage checks
│   ├── make_preview.py      # rebuilds preview/index.html
│   └── preview_template.html
├── preview/
│   ├── index.html           # player nel browser per ogni cue
│   └── avatar.png           # icona del tema (512×512)
├── LICENSES/
├── Makefile
└── install.sh

Character

Voyager is a probe on the edge of the heliosphere. Voices are pushed through narrowband bandpass filtering, amplitude-modulated by a square tremolo at 9 Hz and quantised to 7 bits with sample-and-hold, so every cue carries the artefacts of a link that is barely holding. Telemetry beep patterns carry the state information; there is a noise floor underneath almost everything.

Motif	Used for
Narrowband AM radio burst	message, calling, attention
Telemetry beep pattern	state, busy, authentication
Square-tremolo degradation	every transmission artefact
Low telemetry root, spare bass	probe-console character
Sonar sweep with noise floor	scan, probe return

Requirements

• KDE Plasma 6, or any desktop implementing the freedesktop sound theme spec
• nothing at runtime — the cues are plain Ogg Vorbis files
• ffmpeg (libvorbis), python3, numpy, scipy only if you want to regenerate the audio

Install

User-local (recommended, no root needed):

git clone https://git.enne2.net/enne2/kde-sound-theme-voyager.git
cd kde-sound-theme-voyager
./install.sh              # copies Voyager/ into ~/.local/share/sounds/

System-wide:

sudo make install-system  # copies Voyager/ into /usr/share/sounds/

Select the theme

System Settings → Colors & Themes → System Sounds → Voyager

Or from the command line:

kwriteconfig6 --file kdeglobals --group Sounds --key Theme Voyager

To go back to the Plasma default:

kwriteconfig6 --file kdeglobals --group Sounds --key Theme ocean

The theme declares Inherits=freedesktop, so any event it does not provide (e.g. multi-channel test signals) falls back to the stock desktop theme instead of going silent.

What is inside

Voyager/index.theme declares the theme, Directories=stereo, OutputProfile=stereo and Example=theme-demo. The Example key is what the Plasma System Sounds KCM uses for its preview button, so theme-demo.oga is a montage of the theme's signatures rather than an arbitrary cue.

Name[it] and Comment[it] are also provided, so Plasma in an Italian locale lists the theme as Voyager. That is a display name only: the theme id — the folder name in ~/.local/share/sounds/ and the value written to kdeglobals — is always Voyager, exactly like KDE's own Ocean theme shows up as Oceano in Italian.

sound name	duration	size
alarm-clock-elapsed	2.66 s	43.6 KiB
audio-test-signal	1.10 s	21.1 KiB
audio-volume-change	0.13 s	6.7 KiB
battery-caution	1.18 s	22.2 KiB
battery-full	1.05 s	20.4 KiB
battery-low	1.18 s	21.0 KiB
bell-terminal	0.15 s	7.1 KiB
bell-window-system-attention	0.94 s	18.0 KiB
bell-window-system	0.88 s	17.1 KiB
bell	1.26 s	21.3 KiB
button-pressed-modifier	0.12 s	7.1 KiB
button-pressed	0.11 s	6.9 KiB
camera-shutter	0.26 s	9.7 KiB
complete-media-burn	2.26 s	40.0 KiB
complete-media-error	1.72 s	35.1 KiB
complete	0.83 s	16.9 KiB
completion-fail	1.38 s	23.0 KiB
completion-partial	1.12 s	20.2 KiB
completion-rotation	1.68 s	28.2 KiB
completion-success	2.14 s	38.2 KiB
desktop-login	2.90 s	45.4 KiB
desktop-logout	2.20 s	32.7 KiB
device-added	0.64 s	15.5 KiB
device-removed	0.64 s	15.2 KiB
dialog-error-critical	2.32 s	44.2 KiB
dialog-error-serious	1.80 s	36.2 KiB
dialog-error-veryserious	2.70 s	40.2 KiB
dialog-error	1.48 s	32.1 KiB
dialog-information	1.13 s	20.6 KiB
dialog-question	1.14 s	21.9 KiB
dialog-special	1.86 s	35.9 KiB
dialog-warning-auth	1.00 s	19.5 KiB
dialog-warning	1.27 s	22.2 KiB
game-over-loser	2.60 s	47.9 KiB
game-over-winner	3.02 s	54.3 KiB
media-insert-request	0.87 s	17.7 KiB
message-attention	1.16 s	23.7 KiB
message-contact-in	1.05 s	19.4 KiB
message-contact-out	1.05 s	19.3 KiB
message-highlight	0.86 s	18.3 KiB
message-new-email	1.48 s	26.8 KiB
message-new-instant	0.92 s	17.3 KiB
message-sent-instant	0.45 s	10.6 KiB
message	0.80 s	16.6 KiB
network-connectivity-established	1.66 s	30.7 KiB
network-connectivity-lost	1.26 s	22.4 KiB
outcome-failure	1.32 s	29.1 KiB
outcome-success	1.62 s	30.3 KiB
phone-incoming-call	2.44 s	44.3 KiB
phone-outgoing-busy	1.30 s	24.2 KiB
phone-outgoing-calling	1.16 s	23.7 KiB
power-plug	0.78 s	16.0 KiB
power-unplug	0.88 s	18.6 KiB
screen-capture	0.30 s	10.2 KiB
service-login	1.34 s	23.5 KiB
service-logout	1.24 s	22.2 KiB
suspend-error	1.92 s	38.0 KiB
theme-demo	11.39 s	185.1 KiB
trash-empty	0.95 s	19.8 KiB
window-attention	1.43 s	24.4 KiB
window-question	1.04 s	20.6 KiB

Rebuilding from source

The audio is generated, not sampled, so it is fully reproducible:

make generate     # rewrites Voyager/stereo/*.oga from tools/gen_sounds.py
make verify       # spec + audio + KDE coverage checks
make preview      # rebuild preview/index.html
make dist         # build dist/kde-sound-theme-voyager-1.0.0.tar.gz

make verify fails loudly on a clipped sample, a DC offset, a click at a file edge, a wrong sample rate or channel count, a missing stereo directory in Directories=, a broken Example/Inherits reference, and it reports how many of the sound names actually requested by the installed KDE *.notifyrc files the theme resolves.

Design notes

One instrument set, not sixty unrelated beeps

Every cue is assembled from the same small library of motifs — FM bells, sub impacts, band-limited noise sweeps, additive pads, plucked strings, telemetry blips — so the theme reads as a single instrument rather than a folder of noises. The palette below is what turns that library into this theme:

Parameter	Voyager
Root	E3 — 164.81 Hz
Scale	pentatonic (0 2 5 7 9)
FM voice	ratio 3.5, index 3.0, index decay 90 ms
Detune	±4 cents, degraded by 7-bit quantisation
Space	1.7 s sparse, grainy hall at low density (a room made mostly of vacuum)

A differentiated reverb bus

A single reverb setting is wrong for a desktop theme: frequent cues (chat, volume, button clicks) would smear into each other during a burst, while rare dramatic cues would sound dry and small. Cues here are assigned one of five reverb classes — from near-dry clicks through a small room up to a vast hall with an extra half-second of tail — by motif, with per-sound overrides. The result is that a chat notification stays crisp and a login blooms.

Loudness-aware normalisation

Peak-normalising every file is not enough: a sparse bell and a dense error cluster end up at wildly different perceived levels. After peak normalisation each cue gets a bounded gain (±6 dB) that pulls the RMS of its active portion towards −16 dBFS, with the peak ceiling always winning. That keeps the theme consistent without introducing clipping.

No clicks

Every cue is high-passed (30–130 Hz depending on the class), given a 1.5 ms raised-cosine fade in and a 35 ms fade out before the reverb is applied, so the convolution never sees a discontinuity. make verify enforces this: it rejects any file whose first samples are not at zero.

Licence

• Audio (Voyager/stereo/*.oga, Voyager/index.theme) — CC BY-SA 4.0, the same licence the KDE sound themes use.
• Code and documentation (tools/, Makefile, install.sh, preview/, README.md) — BSD-2-Clause.

The sounds are original synthesis; nothing is derived from the KDE Ocean sound theme or any other recording. You may therefore use this theme commercially and adapt it freely, subject to CC BY-SA 4.0's attribution and share-alike terms.

Credits

Created by enne2 (2026). Designed for Plasma 6.3 on Debian 13.

The avatar illustration in preview/avatar.png is an AI-generated image (Google Gemini via Antigravity). It is included only to identify the theme, and is not covered by either grant below: neither the CC BY-SA 4.0 that applies to the audio nor the BSD-2-Clause that applies to the code.