MBROLA is

speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal langua ...

software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

as a worldwide collaborative project. The MBROLA project web page provides diphone databases for many spoken

language Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing syste ...

s. The MBROLA software is not a complete

system for all those languages; the

text Text may refer to: Written word * Text (literary theory) In literary theory, a text is any object that can be "read", whether this object is a work of literature, a street sign, an arrangement of buildings on a city block, or styles of clothi ...

must first be transformed into

phoneme A phoneme () is any set of similar Phone (phonetics), speech sounds that are perceptually regarded by the speakers of a language as a single basic sound—a smallest possible Phonetics, phonetic unit—that helps distinguish one word fr ...

and

prosodic In linguistics, prosody () is the study of elements of speech, including intonation (linguistics), intonation, stress (linguistics), stress, Rhythm (linguistics), rhythm and loudness, that occur simultaneously with individual phonetic segments: v ...

information in MBROLA's format, and separate software (e.g. eSpeakNG) is necessary.

History

MBROLA project started in 1995 at the TCTS Lab of the Faculté polytechnique de Mons (Belgium) as a scientific project to obtain a set of speech synthesizers for as many languages as possible. The first release of MBROLA software was in 1996 and was provided as

freeware Freeware is software, often proprietary, that is distributed at no monetary cost to the end user. There is no agreed-upon set of rights, license, or EULA that defines ''freeware'' unambiguously; every publisher defines its own rules for the free ...

for non-commercial, non-military application. Licenses for created voice databases differ, but are also mostly for non-commercial and non-military use. Due to its free usage only for non-commercial applications, MBROLA was as alternative choice for private/home users for de facto

engine eSpeakNG in

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

workstations, but mostly was not used for commercial solutions (e.g. for speaking time clocks, boarding notifications for ports and terminals etc.) After initial development of voice databases updates and support of MBROLA software ceased and gradually closed-source binaries fell behind development of recent hardware and operating systems. To deal with this MBROLA development team decided to release MBROLA as

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

software, and on October 24, 2018, source code was released on GitHub with

GNU Affero General Public License The GNU Affero General Public License (GNU AGPL) is a free, copyleft license published by the Free Software Foundation in November 2007, and based on the GNU GPL version 3 and the ''Affero General Public License'' (non-GNU). It is intended fo ...

. On January 23, 2019, tool called MBROLATOR was released to provide creation of MBROLA database from

WAV Waveform Audio File Format (WAVE, or WAV due to its filename extension; pronounced or ) is an audio file format standard for storing an audio bitstream on personal computers. The format was developed and published for the first time in 1991 ...

files with the same license.

Used technology

MBROLA software uses MBROLA (Multi-Band Resynthesis OverLap Add)

algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

for speech generation. Although it is

diphone In phonetics, a diphone is an adjacent pair of phones in an utterance. For example, in aɪfəʊn the diphones are a ɪ �f ə �ʊ �n The term is usually used to refer to a recording of the transition between two phones. In the following ...

-based, the quality of MBROLA's synthesis is considered to be higher than that of most diphone synthesisers as it preprocesses the diphones imposing constant pitch and

harmonic In physics, acoustics, and telecommunications, a harmonic is a sinusoidal wave with a frequency that is a positive integer multiple of the ''fundamental frequency'' of a periodic signal. The fundamental frequency is also called the ''1st har ...

phases that enhances their concatenation while only slightly degrading their segmental quality. MBROLA is a time-domain algorithm similar to PSOLA, which implies very low computational load at synthesis time. Unlike PSOLA, however, MBROLA does not require a preliminary marking of pitch periods. This feature has made it possible to develop the MBROLA project around the MBROLA algorithm, through which many speech research labs,

companies A company, abbreviated as co., is a legal entity representing an association of legal people, whether natural, juridical or a mixture of both, with a specific objective. Company members share a common purpose and unite to achieve specifi ...

, or

individual An individual is one that exists as a distinct entity. Individuality (or self-hood) is the state or quality of living as an individual; particularly (in the case of humans) as a person unique from other people and possessing one's own needs or g ...

s around the world have provided diphone

database In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...

s for many languages and voices.

References

MBROLA source code repository

External links

MBROLA voices (database for MBROLA speech synthesizer)

MBROLATOR (database creation tool for MBROLA speech synthesizer)
{{Speech synthesis Speech synthesis Computational linguistics