I'm also having the same problem: Roku Media Player briefly drops the sound several times a minute. So frustrating!
It does it on lots of files. I'm not super knowledgeable about codecs. If I'm reading VLC Media Player correctly (just used for comparison to Roku Media Player) this one's audio is
A/52 B Audio (aka E-AC3) (eac3)
Sample rate 48,000 Hz
Bits per sample 32
I have confirmed that two other players do not cause this audio glitching on this file.
Roku--please fix your software!!!