I found this tutorial http://webmaxtor.blogspot.com/2012/05/convert-wav-to-8-bit-8-khz-u-law-format.html, and they showed how to export U-law files
Here is what they said to do:
In Audacity with your file open, confirm the project rate is 8000 (shown in lower left corner of progress bar).
Then, choose Edit | Preferences | File Formats.
In the Uncompressed Export Format, choose Other…
Then, in Header, choose WAV (Microsoft) and in Encoding, choose U-Law.
Then, choose File | Export as WAV and simply name it appropriately.
However, I can’t find anything under preferences on my mac newest audacity. Is there an option on this somewhere? I need ulaw files for an operating system for a ham radio repeater I am building.
It is rarely a good idea to read online tutorials on other sites. The tutorials are often incorrect or don’t say what version of Audacity or what operating system they relate to. We have an online Manual that is always current for the current release of Audacity. You can search it by clicking this link: http://tinyurl.com/poapb5o .
Assuming you are using the latest Audacity 2.0.5 from http://audacityteam.org/download/mac, you choose the export options when you export, not in Preferences. Please see the first link in http://tinyurl.com/poapb5o .
Before export, choose the correct sample rate for the export in “Project Rate” bottom left. You are being asked for 8 kHz, so choose 8000 Hz project rate.
Then File > Export… , choose “Other uncompressed files”, click the Options… bottom right, then choose WAV (Microsoft) header and U-Law encoding. The U-Law encoding sets 8-bit for the exported WAV.
Make sure this is a mono file. If it is stereo, click above Mute / Solo to select the track, then choose Tracks > Stereo Track to Mono.
By the way, on a Mac, Preferences are under the “Audacity” Menu.