[Pynkrabbit]

It's also a free resource so the phrase "you get what you pay for" comes to mind.

[hmottestad]

That's a terrible reason for not getting the sound right. Khan Academy is free, and they have good sound.

[HiroshiSan]

To the courses defense, It's in an open classroom environment, while Khan Academy is Khan sitting at his computer, so it's much easier to get the sound right.