We use the app "Educreations". It is free and it allows the students to "draw" their words and then record themselves reading the list.
Below is an example of a student's work in this app. After the child writes the sort, he/she taps the record button and reads the word sort. Then they hit the save button. This sends the picture and recording in to the app for future use.
When they are finished saving, I have them listen to themselves and think about what they heard. This self assessment is very powerful. The recording also shows the time it takes and I've heard several comment on this. The draw back to this app is that the student cannot go back and re-record after they have saved it. Plus, if the recording has an error, then the whole thing is lost and they must start over again. This happened several times but we still like using this app, so we just deal with it. I hope this glitch gets fixed by the designer soon. I have the students complete this assignment 2 times in the week. Once at the start and again at the end of the week. This way they can hear the difference and see how practice has improved their fluency and speed.
My take away from this is that when I have the students read their words as they sort and then read them again for a partner, they are working on fluency, which is great, but when they listen to themselves read, they are working on self assessment. I've watch my students pause on a word that they heard themselves say slowly or wrong and they catch it and then practice saying it correctly. When they do this as just a read, they may not catch their errors but when they listen to themselves it is so much more powerful!