Re-voicing the Past: The AT-ST Project

We can read the words of the past, but we can’t hear them. The ink on a thousand-year-old manuscript can preserve a story, a poem, or a law, but the voice of the person who wrote it is lost to the silence of history. What did Old High German, the language of Charlemagne’s era, actually sound like? Was it the harsh, guttural tongue of stereotypes, or something more melodic? This question, once confined to the educated guesses of historical linguists, is now being answered by an extraordinary fusion of medieval studies and modern technology: the “Audio-visual corpus of Old German” project, or AT-ST.

This groundbreaking initiative isn’t about finding ancient audio recordings; it’s about digitally recreating a lost soundscape. It’s a project that re-voices the past, allowing us to listen in on a world that has been silent for centuries.

The Silent Evidence: Why Recreating Ancient Sound is So Hard

The fundamental challenge is that writing is an imperfect map of speech. Alphabets are brilliant tools, but they are always an approximation. Think about English: the letters ‘ough’ can be pronounced in at least ten different ways (think through, though, rough, cough, bough). Now imagine trying to reconstruct the sound of English a thousand years from now with only written texts and no speakers.

Historical linguists face this exact problem. They can’t just interview a native speaker of Old High German (OHG), which was spoken roughly from 750 to 1050 AD. The language evolved, shifted, and branched into the dialects that would eventually become Modern German. The link between the written symbol (the grapheme) and the spoken sound (the phoneme) has to be painstakingly rebuilt from scratch.

Cracking the Code: Clues Hidden in Medieval Poetry

If there are no recordings, where do researchers find the clues? The answer, brilliantly, lies in art. The AT-ST project turns to the most structured and sound-sensitive texts we have from the period: medieval poetry.

Poets are masters of sound, and their techniques leave behind a fossil record of pronunciation. The researchers act as phonological detectives, analyzing several key features:

• Rhyme: This is the most powerful tool. When two words rhyme, it tells us that their ending sounds were identical, or at least very similar, to the poet and their audience. For example, in the 9th-century Evangelienbuch by Otfrid von Weissenburg, words like rîtan (to ride) and strîtan (to strive) rhyme. This confirms that the ‘î’ in both words represented the same long vowel sound. By building a massive network of these rhyming pairs, linguists can group words into sound-alike families and begin to reconstruct the vowel system.
• Alliteration: A technique common in older Germanic poetry, like the famous Hildebrandslied, alliteration involves repeating the same sound at the beginning of words in a line (e.g., “Hiltibrant enti Hadubrant”). This helps confirm which consonants were considered the “same” sound.
• Meter: The rhythm and stress pattern of a poetic line reveal which syllables were stressed and which were not. This is crucial for understanding vowel length and the overall musicality of the language. A line of poetry only “scans” correctly if you pronounce the words as the poet intended.

By combining these internal clues with the comparative method—analyzing how OHG sounds evolved into Middle and Modern German, and how they relate to sister languages like Old English and Old Saxon—linguists can formulate a highly detailed hypothesis about the phonology of Old High German.

From Theory to Voice: The Technology of Resurrection

This is where the AT-ST project takes a leap into the 21st century. Having a theoretical model of OHG pronunciation is one thing; hearing it is another. This is achieved through advanced speech synthesis.

The process is multi-layered:

1. Corpus Creation: First, the team digitizes key OHG texts, creating a machine-readable corpus. This includes seminal works like the Hildebrandslied, the Muspilli, and Otfrid’s Gospel Book.
2. Phonetic Transcription: Each word in the corpus is then painstakingly transcribed into the International Phonetic Alphabet (IPA). This is the crucial translation step. The OHG spelling “naht” (night) isn’t just typed as “naht”; it’s converted into its reconstructed phonetic form, likely [naxt], explicitly noting the open ‘a’ sound and the voiceless velar fricative [x]—the “ach” sound of German and Scottish “loch.”
3. Articulatory Synthesis: The project uses a sophisticated form of text-to-speech (TTS) called articulatory synthesis. Instead of just stitching together pre-recorded sound snippets, this technology uses a computer-generated 3D model of the human vocal tract—including the tongue, lips, jaw, and velum. The phonetic transcription is fed to this model, which then simulates the physical movements required to produce those sounds.

The result is startling. The AT-ST project has developed digital avatars—whimsically named Hilde and Brand after the characters in the Hildebrandslied—that can “speak” the reconstructed language, their virtual mouths moving in sync with the sounds being produced. It is the closest we have ever come to witnessing an Old High German conversation.

So, What Did Old High German Sound Like?

Listening to the AT-ST project’s recreations is a fascinating experience. Some aspects are familiar to speakers of Modern German, while others are strikingly different.

“Ik gihorta dat seggen, dat sih urhettun ænon muotin…”
(I heard it said, that champions met each other in single combat…)
– Opening line of the Hildebrandslied

When spoken by the AT-ST synthesis engine, several features stand out:

• Fuller Vowels: Vowels in unstressed final syllables, which are often reduced to a neutral “schwa” sound in Modern German (like the ‘e’ in “Hunde”), were likely pronounced more fully in OHG. This gives the language a more robust, sonorous quality.
• True Diphthongs: Vowel combinations like <ie> and <uo>, which in Modern German have become single long vowels (e.g., Liebe is pronounced “lee-buh”), were true diphthongs in OHG. You would have heard both vowel sounds gliding into one another, more like “lee-eh-buh.”
• A Rolled ‘R’: The ‘r’ was almost certainly an alveolar tap or trill, similar to a modern Spanish or Scottish ‘r’, not the uvular ‘r’ common in many parts of Germany today.

The overall effect is a language that sounds both archaic and powerfully alive. It connects the silent, static words on the page to the dynamic, physical act of human speech.

A Bridge Between Past and Future

The AT-ST project is more than just a technological curiosity. It is a profound act of cultural and linguistic restoration. For scholars, hearing the poetry of Otfrid with its intended rhymes and rhythms offers new insights into his artistry. For students and the public, it transforms Old High German from an abstract academic subject into a tangible, audible piece of our shared heritage.

By blending the meticulous analysis of the humanities with the innovative power of computational linguistics, the AT-ST project has built a bridge across a thousand years of silence. It reminds us that language is, at its heart, a spoken and heard phenomenon, and it allows us, for the first time, to truly re-voice the past.