MedievalLatina

There are good text-to-speech engines for English and classical Latin, but none for medieval Latin. MedievalLatina converts Latin text to a kind of phonetic spelling that can be read by English language text-to-speech engines.

Hear it

A line of the Lord's Prayer — Pater noster qui es in caelis — spoken by Amazon Polly using this gem's IPA pronunciation lexicon, so you hear MedievalLatina's pronunciation rather than raw Latin:

▶️ Play the sample (audio/pater-noster.mp3)

  • Text: Pater noster qui es in caelis — "Our Father, who art in heaven", the traditional Latin Lord's Prayer (public domain).
  • Gem output: MedievalLatina["Pater noster qui es in caelis"] → "pah-tare nohstayr kwee es een chaylees".
  • Voice: Amazon Polly Bianca (Italian, it-IT, neural engine), driven by MedievalLatina's IPA via a PLS lexicon.
  • Reproduce: ruby -Ilib bin/sample_audio Bianca (requires AWS credentials in the environment and the aws-sdk-polly gem).
  • Provenance: audio generated with Amazon Polly on 2026-06-07; Polly output may be used and redistributed under the AWS Service Terms.

Installation

Add this line to your application's Gemfile:

gem 'medieval_latina'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install medieval_latina

Usage

Help English language text-to-speech engines pronounce Latin

["caelum", "omnia", "pugno"].each { |word| puts MedievalLatina[word] }
=> "chayloom"
=> "ohm-nia"
=> "poon-yoh"

sentence = MedievalLatina["sed libera nos a malo"]
=> "sayd leebayrah nohs ah mahloh"

let sentence = "...";
responsiveVoice.speak(sentence, "UK English Female");

Generate lexicons to override text-to-speech pronunciation

polly = Aws::Polly::Client.new
s3 = Aws::S3::Client.new

# Lowercase so the text matches the lexicon's (case-sensitive) lowercase graphemes.
sentence = "pater noster qui es in caelis"

words = sentence.split(" ")
pronunciations = MedievalLatina.pronunciations_for(words)
lexicon = MedievalLatina::LexiconBuilder.new(pronunciations).call

name = "CustomLatin"
polly.put_lexicon(name: name, content: lexicon.to_s)

# Synthesize speech using the lexicons
response = polly.synthesize_speech(
  lexicon_names: [name],
  text: sentence,
  output_format: "mp3",
  voice_id: "Joanna"
)

# Read the audio data and store it in a variable
audio_data = response.audio_stream.read

bucket_name = "foo"
object_key = "bar/pater-noster.mp3"

s3.put_object(
  bucket: bucket_name,
  key: object_key,
  body: audio_data
)

Latin langauge helper methods

MedievalLatina.verb?("voco")
=> true

MedievalLatina.verb?("nauta")
=> false

MedievalLatina.adverb?("facile")
=> true

MedievalLatina.adjective?("certus")
=> true

MedievalLatina.noun?("canis")
=> true

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment. Maintain project style by running bin/lint before commiting changes.

To install this gem onto your local machine, run bundle exec rake install.

To release a new version:

  1. Update the version number in version.rb
  2. Run bin/setup to increment the version in the lock file
  3. Run bundle exec rake release

Rebuild the lexicon files when you add new International Phonetic Alphabet pronunciations. You do this by running: bin/build

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/jaysonvirissimo/medieval_latina. Run bin/lint before submitting any changes, to help keep the code formatting uniform.

License

The gem is available as open source under the terms of the MIT License.