How To record custom voice prompts

Introduction

As a minimum you will most certainly want to customize your system greeting. This page provides a brief introduction on how to self-record a new system greeting or, alternatively, how to add a professionally recorded greeting to the sipX system.

Voice Prompt File Format and Location

All the sipX voice prompts are *.wav files. They are located in /usr/share/www/doc/stdprompts.

The audio format we use is:

RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bits, mono, 8000 Hz  

Voice Prompt Files There are almost 500 different .wav files that comprise the total vocabulary of sound bites that sipX is able to speak. These sound bites are assembled into sentences using VoiceXML scripts. Most file names of the .wav files sufficiently explain their content. A complete listing can be found in the document referenced below. Additional information in .pdf format can be downloaded from the SIPfoundry main site. you need to be signed in on the SIPfoundry site to see the files. Especially relevant to localization is the file Localization_of_Voice_Apps.pdf.

Recording Voice Prompts

Recording voice prompts use 8kHz sampling, mono, and 16 bits per sample and save as Microsoft PCM .wav file.

Recording your own prompts you might want to try Audacity. This is an open source application available for Mac OS X, Microsoft Windows, and GNU/Linux and it is used for music recordings. It represents a good mix between powerful features and high usability (i.e. it is simple to use). Normalizing the volume after recording will most likely improve your results. Audacity also provides a noise reduction capability that shall be recommended.

A commercial alternative to Audacity is Adobe Audition. Record your source material using a high (at least 44Khz) sample rate, apply filters or normalization, then down sample the recorded audio to 8,000 Hz and save the file in Windows PCM wav (16 bit) format.

Avoid background noise when recording and use a reasonable quality microphone (don't hold it in your hand). It is also a good idea to make sure that you have access to your voice model in the future as you might have to do additional recordings and you do not want to change the voice.

Tip

If you don't need music as part of your Voice Prompt, another easy method of recording your voice prompts is to dial your voicemail box (8 and your extension), record the Voice Prompt as you want it. Then go into the user menus, right click on the voicemail file and save the WAV file to your local computer then upload it to the proper AA.

Converting Audio Files

For converting audio files into the format used by sipX, we recommend sox. This is a simple yet powerful tool to convert many different formats of audio files. For instance, it would be possible to convert MP3 music files into the sipX format to be used by the call park server to play music on hold.

Uploading Audio Files

Voice prompts can be uploaded using the sipX Configuration Server.