Ticking sound after about 3 minutes of recording voices

Hi, I’m new to audacity

I am using Audacity version 2.1.1
On a MacBook Pro (from Mid 2009) using OS X 10.10.5
and I downloaded the Audacity .dmg installer

My wife is using
Audacity version 2.1.0
On a MacBook Pro (from Mid 2010) using OS X 10.10.3
and she downloaded the Audacity .dmg installer

We both encounter the samen problem: After aprox. 2-3 minutes of recording time a static sounding ticking noise spoils the recording.
It doesn’t happen every time, but it happens regularly and is very annoying. We both use the build in microphone of our MacBook.

I include a sound sample for you to analyse. Is there something we are doing wrong and/or how can this be prevented?

Thanks, Briant

Audacity > Preferences…, Recording section. Set Audio to buffer to 0 and try to record. If it doesn’t record, try a setting of 10 and increment upwards until you find the lowest setting it will record at.

Turning Wi-Fi off may help too.