How to make CCITT mu-law files for older IVR systems using Audacity

Hey, there!

I came THIS close to spending nearly $400 this weekend that I didn’t need to.

I was saved by experimentation. And I’m going to save you too – especially if you do IVR work for older phone tree systems.

Here’s how.

(And do refer back to this little snippet of a screenshot when I reveal this Secret.)

So, what’s the secret of using Audacity to create phone prompt WAV files for ancient IVR systems?

I do a lot of IVR work – and it’s one of my most popular classes. I’m the on-hold voice, the voice you get mad at while you’re waiting for the opportunity to get mad at a real live person, for many of the Fortune 5000, including AOL.

AOL has systems that go back decades (I’ve been their voice since 1988), and although I can send them WAV or MP3 files for the modern systems they use, those older legacy systems are really picky about what kind of files they can play to callers.

In fact, they are so old and outdated that most sound converters don’t even offer the option to convert regular old WAV files into what these older systems want.

(For you techies, the older systems don’t want standard PCM encoded 16 bit 44.1K full fidelity WAV files, they want CCITT mu-law encoded 8 bit 8K files. Why? Storage was a premium consideration in The Old Days – these files are tiny compared to standard WAV files.)

I recently revamped my studio, and got rid of a number of older Windows machines, one of which had an app built into the operating system that would convert these files just fine.

But…alas, no longer do I have that tool at my disposal.

And after hours of testing every Macintosh sound editing and conversion software out there, including Switch, Sound Converter, Fission, ProTools, ffmpeg and front-ends for ffmpeg, And I finally found an expensive solution: BarbaBatch. The demo worked like a charm on my files.

Problem: BarbaBatch costs $395. Ick. But, I was ready to buy it – I mean, AOL pays me big bucks to do their phone prompts, and they need to be kept happy.

But, I kept searching. And searching, and searching. And in the week hours of Sunday morning, I stumbled on a process, posted not on a VO site, but on a Cisco tech site, that would allow me to use good old Audacity:

First, record and normalize your prompt in mono.

Then, in the lower left hand corner of your Audacity project screen, change the Project Rate to 8000 (it will most likely be at 44100).

Then, export your file using the “Other Uncompressed Files” option in the Save dialog box, and choose WAV (Microsoft) as your Header and U-law as your Encoding in the drop down menus. Then, save your file with the .wav extension.

Voila. CCITT mu-law (aka U-law) 8k 8-bit mono wav files.

My client at AOL confirmed that they worked perfectly on their older systems, and actually sounded better than any of the BarbaBatch converted samples.

Nothing about this process was even remotely intuitive, but it worked. And as a VO artist with a home studio and a bent to serve clients, these are the little skills you never know whether or not you’ll need – until you need them.

I hope this helps. And I hope you get the kind of IVR gig that I’ve had with AOL for the last 28 years or so – and NEED this!


9 Responses to 6 Steps to a Perfect VO Demo

  1. Kelli August 18, 2011 at 2:58 am #

    I feel really good about my demo. It is a quick and fun process, even for someone like me who gets very self concious. :)

  2. David Britz September 5, 2011 at 11:25 pm #

    The demos are great. Superb quality. Why go anywhere else?

  3. David Britz October 20, 2011 at 3:51 pm #

    Can’t wait to record my Narration VO Demo!! :))

  4. Mike Brang December 31, 2013 at 9:44 am #

    Having a well-produced demo is one of the most important things in the VO business. I had a number of demos made from other producers in the past and they all had one thing in common — that manufactured, cookie cutter sound!
    What sets David apart from the rest, besides his affordable price and tremendously fast turn around time, is that all of the clips you record with him sound unique. Each spot sounds like an actual commercial you recorded for a job.
    My agent loved the quality and even asked who produced it to refer his other talent there!

    Thanks again, David for producing such a great, high quality demo for me. You made the process relaxing and enjoyable. I urge anyone reading this unsolicited reply to listen to David’s student demos to hear the difference for yourself. Anyone would be lucky to work with him

  5. Kristy Liles February 9, 2017 at 7:04 pm #

    I can not thank you enough. I worked so hard on 15 page IVR project, one day I cryed, look for answers, pull my hear (not really) but I was about until another VO send me this great tool. Thanks!

  6. Frank June 11, 2017 at 9:51 pm #


    When v123 indicates the audition is for a student/ nonprofit are we to assume it is for $0. If so, why does the audition ask for an amount to be entered?

  7. shirley jordan June 12, 2017 at 5:58 pm #

    I did get this scam through Voice 123. In our discourse, they offered me the gig and they gave me the name of a legit local place to record and the same runaround with the money. I didn’t send anything, but instead, I called the studio to make sure the booking was for the day we set up, and lo and behold, the people there had no idea what I was talking about. I then tried to call back my “contact person” who was setting this up and there was a fax machine beep on the other end. I immediately contacted Voice 123 and told them what had happened. You know what they say…if it sounds togaed to be true, it probably is. Thanks for the reminder!

  8. shirley jordan June 12, 2017 at 5:59 pm #

    …too good…not togaed.
    The one time spell check didn’t work!

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