Third-party notices

Voictrum is © 2026 the voictrum contributors, all rights reserved (see LICENSE). It contains, or is derived from, the third-party works below, which are used under their own licences. Those licences apply to those parts and are not changed by Voictrum's own terms. This file is published on the site as /notices (web/site/assemble.py makes notices.html from it).

Pink Trombone

Voictrum's voice engine is built on Pink Trombone by Neil Thapen (dood.al/pinktrombone). The glottis (src/voictrum/Glottis.h) and the vocal tract (src/voictrum/Tract.h) are faithful C++ ports of Pink Trombone's Glottis and Tract, and the shaping layer of src/voictrum/Voice.h (the tongue curve, constriction shaping and fricative ramps) is ported from Pink Trombone's UI layer. The engine compiled into the site (engine.wasm, and the single page) contains this code. It is used under the MIT License:

Copyright 2017 Neil Thapen

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.

Simplex noise

src/voictrum/SimplexNoise.h is ported from the public-domain simplex noise implementation by Stefan Gustavson (JavaScript conversion by Joseph Gentle), as used in Pink Trombone.

CMU Pronouncing Dictionary (CMUdict)

The English pronouncing dictionary (assets/lexicon.txt, served as lexicon.txt) is derived from CMUdict. The letter-to-sound rules (assets/lts_rules.txt, served as lts_rules.txt) are learned from that dictionary by tools/build_lts.py, and the carols' and motets' word sounds (assets/chant/*.sounds.json) are read through it. The licence (assets/LEXICON-LICENSE.txt):

The pronunciation lexicon in assets/lexicon.txt is derived from CMUdict.

Copyright (C) 1993-2015 Carnegie Mellon University. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
   The contents of this file are deemed to be source code.

2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in
   the documentation and/or other materials provided with the
   distribution.

This work was supported in part by funding from the Defense Advanced
Research Projects Agency, the Office of Naval Research and the National
Science Foundation of the United States of America, and by member
companies of the Carnegie Mellon Sphinx Speech Consortium. We acknowledge
the contributions of many volunteers to the expansion and improvement of
this dictionary.

THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Unicode Unihan database

The Mandarin reader's character readings (src/voictrum/MandarinTable.inc, compiled into the engine) are derived from the kMandarin field of the Unicode Unihan database. The licence (assets/UNIHAN-LICENSE.txt):

src/voictrum/MandarinTable.inc (the Mandarin reader's character -> pinyin
table) is derived from the kMandarin field of Unihan_Readings.txt in the
Unicode Character Database (Unicode 18.0.0, https://www.unicode.org/Public/UCD/
latest/ucd/Unihan.zip) by tools/build_mandarin_table.py. The Unihan data is
used under the following licence.

UNICODE LICENSE V3

COPYRIGHT AND PERMISSION NOTICE

Copyright © 1991-2026 Unicode, Inc.

NOTICE TO USER: Carefully read the following legal agreement. BY
DOWNLOADING, INSTALLING, COPYING OR OTHERWISE USING DATA FILES, AND/OR
SOFTWARE, YOU UNEQUIVOCALLY ACCEPT, AND AGREE TO BE BOUND BY, ALL OF THE
TERMS AND CONDITIONS OF THIS AGREEMENT. IF YOU DO NOT AGREE, DO NOT
DOWNLOAD, INSTALL, COPY, DISTRIBUTE OR USE THE DATA FILES OR SOFTWARE.

Permission is hereby granted, free of charge, to any person obtaining a
copy of data files and any associated documentation (the "Data Files") or
software and any associated documentation (the "Software") to deal in the
Data Files or Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, and/or sell
copies of the Data Files or Software, and to permit persons to whom the
Data Files or Software are furnished to do so, provided that either (a)
this copyright and permission notice appear with all copies of the Data
Files or Software, or (b) this copyright and permission notice appear in
associated Documentation.

THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF
THIRD PARTY RIGHTS.

IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE
BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,
OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THE DATA
FILES OR SOFTWARE.

Except as contained in this notice, the name of a copyright holder shall
not be used in advertising or otherwise to promote the sale, use or other
dealings in these Data Files or Software without prior written
authorization of the copyright holder.

MakeHuman assets (CC0)

The realistic heads (assets/heads/, served as heads/) are derived from MakeHuman 1.x assets released under CC0 1.0 Universal (public-domain dedication); no MakeHuman program code is used. Attribution, not required under CC0, given anyway: MakeHuman base mesh, targets, rig weights, eyebrows, eyelashes, teeth, tongue, hair and skins by the MakeHuman team; original modelling by Manuel Bastioni and contributors; copyright holders at the CC0 release (September 2020): Data Collection AB, Joel Palmius, Jonas Hauquier (makehumancommunity.org). Beards from the "Bodyparts 05" pack (CC0) by grinsegold, RehmanPolanski and WDG. Details and the licence evidence: assets/heads/LICENSES.md. CC0 legal code: creativecommons.org/publicdomain/zero/1.0/legalcode.

Loaded from other sites (not distributed by Voictrum)

Texts and music

The sacred and literary texts the Choir, Learn and the Lab sing are, as far as their sources state, in the public domain; each piece names its source in the library (assets/chant/*.txt, assets/latin/*.txt). Among the sources named: Divinum Officium (divinumofficium.com) for the Vulgate psalter of the Roman Breviary with the Douay-Rheims English; the Leningrad Codex (UXLC 2.6, tanach.us) for the Hebrew cantillation; the Mahāsaṅgīti edition (SuttaCentral) for Pali; the Geldner edition of the Avesta; the van Nooten and Holland edition of the Rigveda; Wikisource editions of Armenian, Korean and Shinto texts; and the service books of the Eastern churches. The carols are those whose words and tunes are both in the public domain, harmonized by Voictrum. The motet (Arcadelt, adapted by Dietsch, 1842) is encoded by Voictrum from public-domain printings (IMSLP #879525 and #90507) and was cross-checked against Pierre Gouin's edition (CC BY-SA 4.0, IMSLP #125270). The English translations marked as Voictrum's own, the Contemporary pieces, the Lab's passages ("The North Wind and the Sun" in Voictrum's own words) and the encyclopedia's text are Voictrum's work.