Outside sounds while dreaming

In the past I've tried using some of those Lucid MP3s, the ones that play "you are aware that your are dreaming" etc so that you're dream self hears it. They never worked. If I tried playing them while I fell asleep, even during a WBTB, they would never work. If I used it as an alarm, it was either too quiet to hear or too loud that it would wake me up.

This morning I was taking a nap (I'm attempting to transition to polyphasic sleep) and after 20 minutes my usual iPhone alarm went off. However, I didn't wake up. I remember I was having a dream at this point and in my dream heard the noise, which I recognized as "music." I knew it was coming from my iPhone so I tried everything from putting it on mute, to checking the iPod app, to turning it off, to try and stop the sounds. Of course, nothing worked and I just ignored it for the rest of the dream until my backup alarm woke me up 10 minutes later.

I don't understand why I slept through an alarm but not soft lucid MP3s. Is it just due to the exhaustion I was probably experiencing due to lack of sleep from my polyphasic attempt? I'd like to hear people's thoughts on this.

I'm adjusting to polyphasic sleep too (Everyman 3).
My phone alarm lasts for about 5 minutes if I don't push snooze, with increasing volume... it's still waking me up, but about 10-15 seconds later.

I use "The Nap App" on iPhone. It's pretty convenient I just hit the 20 minute "cat nap" button and it starts the countdown. Then it goes off and starts vibrating as well.
It's pretty funny actually because every single time I use it to wake up it takes me a good 10 seconds to figure out how to shut it off. I frantically search for a STOP button before I realize the text on the screen says "Press the Home Button to Turn Off Alarm."

Simple answer... your prefrontal cortex is effectively turned off during sleep. The prefrontal cortex makes sense of abstract ideas. Language is an abstract idea. Sounds are not. Therefore, language is not processed. It is just noise to the sleeping brain. After millions of years of evolution, to the sleeping brain, sounds are there to warn us of trouble ergo your hearing never quite fully goes to sleep . So, yes, you hear sounds in your sleep but no, your brain cannot decipher language because the prefrontal cortex is switched to the off position.