Text to speech applications exist on Windows and Mac that might help. In fact, I think it's built into the Mac.
Whilst it will sound a bit robotic, you can listen, edit and replay immediately.
Maybe do that for the first round of audio drafts and then record one of yourself reading it out. (try Audacity on your computer, assuming you have a built in microphone or get a USB microphone to plug in).
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Text to Speech
Apple OS X comes with more than 20 male, female, and novelty voices, including the extraordinary Alex, a voice so natural that he even breathes when speaking long passages. Using Text to Speech (TTS), you can have Alex and other Mac voices speak selected text so you can hear a word as you see it onscreen. You can adjust the speaking rate to slow things down, and speed them up to adapt to the listeners abilities. Apple TTS voices work with all applications that support the OS X Speech engine, including Mail, Safari, iChat, TextEdit, and many more. The voices included in OS X speak in English, but voices in additional languages are available separately.
If you have a iPhone, thyou can record it as voice memo, the transfer it to iTunes and put it on cd, if you like. I'm not sure if there's a max length for a voice memo, but if there is you can just make as many as you need.
wrt to it sounding robotic, that might be a good thing. I can't remember which creative writing writer it was (John Gardner? Sol Stein?) but one of them talks about taking an excellent class where the teacher insisted on reading aloud the students' work in a monotone so that they learnt that absolutely everything had to be conveyed by the words themselves, with no help from expression or tone or speed from the reader.
Have you thought about joining a critique group? At the one I go to, we have to get someone else to read our work so we can hear how it flows to someone who doesn't know it. Cringeworthy but very helpful!