That very fact is the bit that isn't making sense when we look at Nel's response. What I heard was what appeared to be an automated (robotic) voice of an American lady, or similar. Whatever it was it certainly didn't sound anything like an argument.
Why on earth did Nel explain that it was 'a recording of an argument unrelated to the case', I wonder?
If we look back at the situation, the iPad starts chattering, the court laugh, Nel looks flustered...and then his response should be something like 'I'm so sorry M'Lady, that shouldn't have happened, or 'I'm so sorry M'Lady, I don't know how to switch the iPad off. But, he doesn't. Instead he explains out loud 'it was a recording of an argument unrelated to the case'.
Neither the judge, Roux or anybody else asked Nel who the voice on the iPad was, or what the playback was about. Nel volunteered this statement out of the blue.
Attorneys very very rarely volunteer information that hasn't been requested, unless there's a very good reason for them to do so.