I'm betting there's a mismatch in the audio and your audio hardware settings in AE. What are the specs for the audio clip?
Audio for video should be at a minimum 48Khz and 16bit. You should be using wav or aiff files only. If that does not solve your problems then you need to give us your complete system specs and tell us how you are setting up ram previews. You should also enable show rendering progress in info panel. If the info panel is open you'll see the playback frame rate there.
Convert the voiceover file from an mp3 to either a wav or aiff file, and the probglem goes away.
The clip is a .wav file at 48kHz and 16bits.
I've looked through the preview and audio hardware and couldn't find anything that seemed related. What settings in specific could be influencing this?
Also the info panel says that it's playing back in real time. It looks like the video is playing in real time, it's just the audio that is slowed down.
In case it helps my system specs are:
Model Name: MacBook Pro
Model Identifier: MacBookPro8,3
Processor Name: Intel Core i7
Processor Speed: 2.2 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 8 GB
And specific specs for my audio hardware:
Default Output Device: Yes
Default System Output Device: Yes
Manufacturer: Apple Inc.
Output Channels: 2
Current SampleRate: 48000
EDIT: I got it working after I shut off garageband, spotify, and itunes and restarting AE, could running one of those other programs be messing things up?