Linguistics and TTS

Information on Linguistics and TTS

Intro

Why solving TTS is difficult

One very over-arching reason why text-to-speech is a difficult task is because of the one-to-many problem: one text string corresponds to a infinity of possible acoustic realizations!

Rime has remained fairly opinionated when it comes to the defaults for acoustic realization, but the API also allows you to make extremely low-level adjustments for your particular use case.

Homographs

English’s written form, like many languages’, contains homographs. A homograph is a word that shares the same written form as a word but has one or both of: a different meaning, or a different pronunciation. For the purpose of the Rime TTS API, we are only concerned with the latter. For example, the words sow (verb, to plant seed) and sow (noun, a female pig) are spelled identically but pronounced differently. This poses a problem for any speech synthesis technology, but Rime leverages both contextual syntactic analysis and frequency information to generate likely predictions.

We also provide a straightforward way of overriding these predicted pronunciations:

Homograph Specification Example

# Fruits and vegetables?
text = "I like fresh produce_noun."
# Making things?
text = "They produce_verb a wide array of home goods for decorations."

A complete table of the homographs for which you can specify a disambiguated variant can be found in the Appendix.

Punctuation

Punctuation serves many purposes in normal writing, it indicates sentence structural things like sentence breaks and questions, but it also serves to indicate pronunciation cues, such as commas for pauses and exclamation points for excitement.

For Rime text-to-speech, these various uses are even more flexible. Not only can users employ punctuation for traditional structural purposes, users can modulate the prosody by using differing punctuation. Below we show some basic ways our powerful engine can alter the prosody using punctuation. These are just a few examples, feel free to play around and see what you can create!

Questions

Audio Clip	Sentence	Notes
	what do you mean.	a simple period at the end of the sentence renders it a non-question
	what do you mean?	a simple question mark indicates an unmarked question
	what do you mean?!	adding an exclamation point makes the question more excited
	what do you mean!?	changing the order of the exclamation point and question mark makes a different sort of question
	what do you mean??	multiple question marks can also change the type of question prosody

False Starts

Audio Clip	Sentence	Notes
	i i think it’s pretty cool	putting a word twice in a row can create more realistic, flawed human speech
	i- i think it’s pretty cool	adding a dash immediately after some words can give a cut-off, false start sort of realism

Pauses

Audio Clip	Sentence	Notes
	so it’s kind of funny.	without any comma, there will be no pause
	so, it’s kind of funny.	adding a comma creates a slight pause
	so. it’s kind of funny	adding a period creates a longer pause