Game developers have been hiding images in audio spectrograms since the technique was first demonstrated in the late 1990s. What started as a niche trick has become one of the most popular types of video game easter eggs. Here are the most notable examples, how they were found, and how you can check your own favorite games.
DOOM (2016) - Pentagrams and Demonic Faces
id Software went all-in on spectrogram easter eggs in the 2016 DOOM reboot. Multiple tracks in the soundtrack contain hidden imagery:
The most famous is a pentagram visible in the spectrogram of certain combat tracks. During intense gameplay sections, the music literally contains satanic imagery in its frequency content. Given DOOM's demonic subject matter, this was perfectly on-brand.
The images were placed in frequency ranges above 10 kHz, where they don't noticeably affect the sound of the music. Players discovered them by running the soundtrack through spectrogram analysis software, and the discovery went viral on gaming forums and Reddit.
Mick Gordon, the composer, later confirmed these were intentional. He used spectrogram encoding as part of his sound design process, treating the visual spectrogram as another dimension of the composition.
FEZ (2012) - QR Codes and Puzzle Solutions
Polytron's indie puzzle platformer FEZ is packed with cryptographic puzzles, and several of them use spectrogram-encoded images as clues.
The soundtrack, composed by Disasterpeace, contains hidden QR codes and number sequences in the spectrograms of specific tracks. These weren't just easter eggs - they were integral to solving the game's deeper puzzles. Players who wanted to reach 100% completion needed to analyze the audio.
FEZ's spectrogram puzzles helped popularize "spec-surfing" (scanning spectrograms for hidden content) in the gaming community. The game made audio analysis a gameplay mechanic, which was genuinely innovative.
Undertale (2015) - Gaster and the Mystery Man
Toby Fox's Undertale contains some of the most discussed spectrogram easter eggs in gaming. The track "mus_smile" (associated with the mysterious W.D. Gaster character) contains visual anomalies in its spectrogram that fans have analyzed extensively.
While not all of the supposed spectrogram images in Undertale are confirmed intentional (some may be pareidolia in the natural audio patterns), the community's investigation of these spectrograms has produced an entire subcategory of Undertale lore discussion.
The Gaster mystery demonstrated how spectrogram easter eggs can drive community engagement long after a game's release. Years later, fans are still debating what's intentional and what's coincidental patterns.
Nine Inch Nails - Year Zero (2007)
While not a video game, Trent Reznor's Year Zero ARG is too important to skip. It directly influenced how game developers think about hiding content in audio.
Multiple tracks on the Year Zero album contain spectrogram images, including a hand reaching out and various symbols. These were clues in an elaborate alternate reality game promoting the album. Players had to analyze the audio, decode messages, and follow trails across websites and physical locations.
Reznor later composed the soundtrack for Quake (1996) and has been involved in gaming culture throughout his career. The Year Zero spectrogram technique directly inspired game developers who were fans.
Portal (2007) - Transmission Received
Valve's Portal received an update years after its initial release that added hidden radio signals throughout the game. When players found and carried certain radios to specific locations, the radios played new audio transmissions.
These transmissions contained SSTV (Slow-Scan Television) encoded images - a technique related to spectrogram art. When decoded, the images revealed coordinates and clues that hinted at Portal 2's development. It was one of the most elaborate game announcements ever made.
Minecraft (Disc 11)
Minecraft's mysterious "Disc 11" has been analyzed extensively by the community. The in-game music disc plays distorted, creepy audio that, when viewed as a spectrogram, appears to contain images of a face or figure.
Whether the spectrogram images in Disc 11 are intentional or artifacts of the audio processing is debated. The ambiguity is part of the appeal - Mojang has never confirmed or denied the imagery, which feeds the Minecraft mystery community.
Halo 3: ODST (2009)
Bungie's Halo 3: ODST soundtrack, composed by Martin O'Donnell, contains hidden spectrogram content in certain tracks. The ambient audio that plays during quiet exploration sections of New Mombasa reveals patterns and shapes when viewed as a spectrogram.
How to Find Hidden Images in Game Audio
Want to check your own favorite games? Here's how:
1. Extract the Audio
Game audio files are typically stored as:
-
.oggor.wavfiles in the game directory -
Packed inside game archives (
.pak,.wad,.bank) -
Wwise or FMOD sound banks
Tools like vgmstream, QuickBMS, or game-specific extractors can pull audio from most formats. For Steam games, check the game's installation folder under steamapps/common/.
2. Analyze with a Spectrogram Viewer
Spek is the fastest option: drag and drop any audio file and get an instant spectrogram. Look for unusual patterns, especially in the upper frequency range (above 8 kHz) where hidden images are typically placed.
Audacity gives you more control: you can zoom into specific time ranges and adjust the frequency display range to isolate potential images.
What to look for:
-
Geometric shapes or text that look too regular to be natural audio
-
Images in the ultrasonic range (15-20 kHz) where they're inaudible
-
Patterns that repeat at regular intervals
-
Content that appears during quiet or ambient sections (where it's easier to hide)
3. Adjust Your View
Most spectrogram viewers default to a log frequency scale, which compresses the upper frequencies. Switch to a linear scale to get an undistorted view of high-frequency content where images are often hidden.
Also adjust the dynamic range (dB range) of the display. A wider range (80-100 dB) shows more detail but can make faint images harder to spot. A narrower range (40-60 dB) emphasizes contrast and can reveal images that are mixed at low levels.
Making Your Own Game Audio Easter Eggs
If you're a game developer or modder, adding spectrogram images to your game audio is straightforward. Img2Sound generates audio from any image, and the output can be layered into your soundtrack at a low volume. Place it in ambient tracks, loading screen music, or triggered audio events.
The key considerations:
-
Use frequency ranges above your main music content (8+ kHz for most game audio)
-
Mix at -20 to -30 dB below the main audio level
-
Longer audio durations give better image resolution
-
Test in Spek or Audacity to verify the image reads clearly in the final mix
The best game audio easter eggs serve the game's themes. DOOM's pentagrams fit its demonic setting. FEZ's QR codes fit its puzzle-oriented design. Think about what hidden content would enhance your game's world rather than just being a random novelty.
