Video Transcription

Introduction To Phonetic Spelling

In this video, I'm going to teach you how you can improve your recognition accuracy for certain kinds of speech applications by using a concept called phonetic spelling. By adding words into grammars and spelling them out phonetically, you can overcome some common problems people have with speech recognition.

How Words Are Recognized

When you give us a grammar file, it's basically a plain text file with a list of words that you want recognized. How does the Speech Engine take this list and figure out the way a word will be pronounced?

First, we have the Dictionary file. This contains tens of thousands of words and their associated pronunciations.

There's always a chance that a word you're using isn't in our dictionary. For that, we have a tool called the Phonetic Speller. This contains rules that say "if a word is spelled this way, it's probably pronounced like this".

There is also another way for us to get pronunciations, and that's where you come in. If you spell out a word phonetically in your grammar, we can take that pronunciation and then listen for it. If we hear that combination of sounds, we'll match the rule associated with that phonetic spelling.

Why Use Phonetic Spelling?

For the most part, you won't need to use phonetic spelling. But there are some cases where it is really useful.

Proper Nouns

  • People
    • Uncommon or foreign names
    • Alternative pronunciations
  • Places
  • Business Names

Foreign Words

Accents / Different Dialects


The phoneme is a linguistic term that refers to the idea that within a given language, words are pronounced via discreet units of sound. The phoneme is the smallest unit of sound within that language. If we take the word "cat", we have the beginning sound: "c", the middle: "a", and then the sound at the end: "t". Each one of those sounds is a phoneme.

That example might lead you to believe that each phoneme is a letter in the word, but this is not necessarily true. Phonemes are sounds, not letters.

Phonemes differ for each language. In our Speech Engine Help documentation, we have complete phoneme lists for all the languages we support.


Phonemes are specified as groups of letters, for instance K AE T for "cat".

Phonetic spellings should be represented in double quotes and curly braces:

"{K AE T}"

Within a grammar:

$cat = "{K AE T}";

In the next videos, we'll talk more about phonemes and adding multiple pronunciations. We'll also cover how to add foreign words.


  • This segment delves into how to use phonetic spellings, how pronunciations are generated, an introduction to phonemes, as well as syntax in speech recognition applications.


  • Video Playtime: 11:15



  • Contact Us
  • +1-858-707-7700
  • Toll Free: (877) 977-0707,
    say "Sales"

© 2016 LumenVox, LLC. All rights reserved.