Echos occurring when audio is exported to iTunes

I’ve been using Audacity for the past two years to record audio “letters” and passages from books for a relative with limited eyesight. I’ve had good success using an Olympus Digital Voice Recorder, importing the files to Audacity on my Mac (OS 10.10.4) and exporting them as .mp3 files to be played on an iPhone. In the past few months, however, everything I’ve recorded sounds fine when played in Audacity but has a very annoying echo when the file is played after being exported to iTunes. I’ve updated to the latest 2.1.1 Audacity, added LAME (which I’d never bothered with before) and the problem persists. If I export audio files directly from the digital recorder to iTunes, the sound quality is fine so the issue isn’t with the recorder. It seems like there must be a simple solution for this fairly simply use of Audacity. Could someone kindly point me in the direction of the solution?

I’m curious how to get an MP3 without Lame. I think it’s still true that Audacity won’t create a new MP3 without it.

That’s a serious anomaly right there, but what happens when you export the work, open it in iTunes and get the echo, and then open the exported file in a fresh Audacity.

If it has echoes then, Cut down a piece of it and post it here.