Print the lyrics to "Twinkle Twinkle Little Star"
Python 3 - Partial solution (760 742 734 710 705 657 characters)
(Last edit; I promise)
This seems like a really, pretty, very hard problem (especially recognizing where the notes start or end). Automatic transcription of music seems like an open research topic (not that I know anything about it). So here's a partial solution that doesn't do any note segmentation (eg it prints &quot;Twinkle&quot; all at once when it hears the frequency) and probably only works for that specific ogg file:
A=-52
F=44100
C=4096
import pyaudio as P
import array
import scipy.signal as G
import numpy as N
import math
L=math.log
i=0
j=[9,2,0,2,4,5,7,9]
k=[2,4,5,7]
n=j+k+k+j
w=&quot;Twinkle, |twinkle, |little |star,\n|How I |wonder |what you |are.\n|Up a|bove the |world so |high,\n|Like a |diamond |in the |sky.\n&quot;.split('|')
w+=w[:8]
e=P.PyAudio().open(F,1,8,1,0,None,0,C)
while i&lt;24:
 g=array.array('h',e.read(C));b=sum(map(abs,g))/C
 if b&gt;0 and 20*L(b/32768,10)&gt;A:
  f=G.fftconvolve(g,g[::-1])[C:];d=N.diff(f);s=0
  while d[s]&lt;=0:s+=1
  x=N.argmax(f[s:])+s;u=f[x-1];v=f[x+1]
  if int(12*L(((u-v)/2/(u-2*f[x]+v)+x)*F/C/440,2))==n[i]+15:print(w[i],end='',flush=1);i+=1

This requires...

Python 3 (tested with 3.3 on Windows 64 bit... should work on Mac/Linux in theroy)
PyAudio (I used the windows binary package from here, since the windows binary packages from the PyAudio page didn't work)
SciPy and NumPy (I used scipy-stack from the same site)

Change the A=-52 (minimum amplitude) on the top line depending on your microphone, ammount of ambient sound, how loud the song is playing, etc. On my microphone, less than -57 seems to pick up a lot of extraneous noise and more than -49 requires you play it very loud.
This could be golfed a LOT more; I'm sure there are ways to save a bunch of characters on the words array in particular. This is my first non-trivial program in python, so I'm not very familiar with the language yet.
I stole the code for frequency detection via autocorrelation from https://gist.github.com/endolith/255291
Ungolfed:
import pyaudio
from array import array
import scipy.signal
import numpy
import math
import sys

MIN_AMPLITUDE = -52
FRAMERATE = 44100

def first(list):
    for i in range(len(list)):
        if(list[i] &gt; 0):
            return i
    return 0

# Based on: https://en.wikipedia.org/wiki/Decibel#Acoustics
def getAmplitude(sig):
    total = 0;
    elems = float(len(sig))
    for x in sig:
        total += numpy.abs(x) / elems
    if(total == 0):
        return -99
    else:
        return 20 * math.log(total / 32768., 10)    

# Based on: https://en.wikipedia.org/wiki/Piano_key_frequencies
def getNote(freq):
    return int(12 * math.log(freq / 440, 2) + 49)
        
# --------------------------------------------------------------------------
# This is stolen straight from here w/ very slight modifications: https://gist.github.com/endolith/255291
def parabolic(f, x):
    return 1/2. * (f[x-1] - f[x+1]) / (f[x-1] - 2 * f[x] + f[x+1]) + x

def getFrequency(sig):
    # Calculate autocorrelation (same thing as convolution, but with
    # one input reversed in time), and throw away the negative lags
    corr = scipy.signal.fftconvolve(sig, sig[::-1], mode='full')
    corr = corr[len(corr)/2:]
    
    # Find the first low point
    diffs = numpy.diff(corr)
    
    # Find the next peak after the low point (other than 0 lag). This bit is
    # not reliable for long signals, due to the desired peak occurring between
    # samples, and other peaks appearing higher.
    # Should use a weighting function to de-emphasize the peaks at longer lags.
    start = first(diffs)
    peak = numpy.argmax(corr[start:]) + start
    return parabolic(corr, peak) * (FRAMERATE / len(sig))
# --------------------------------------------------------------------------

# These are the wrong keys (ie it is detecting middle C as an A), but I'm far too lazy to figure out why.
# Anyway, these are what are detected from the Wikipedia .ogg file:
notes = [73,          66,           64,       66,         68,       69,        71,          73,       66,     68,          69,         71,         66,        68,         69,        71      ] 
words = [&quot;Twinkle, &quot;, &quot;twinkle, &quot;, &quot;little &quot;, &quot;star,\n&quot;,  &quot;How I &quot;, &quot;wonder &quot;, &quot;what you &quot;, &quot;are.\n&quot;, &quot;Up a&quot;, &quot;bove the &quot;, &quot;world so &quot;, &quot;high,\n&quot;, &quot;Like a &quot;, &quot;diamond &quot;, &quot;in the &quot;, &quot;sky.\n&quot;]
notes += notes[:8]
words += words[:8]

pa = pyaudio.PyAudio()
stream = pa.open(format=pyaudio.paInt16, channels = 1, rate = FRAMERATE, input = True, frames_per_buffer = 4096)
idx = 0
while(idx &lt; len(notes)):
    # Read signal
    sig = array('h', stream.read(4096))
    if(getAmplitude(sig) &gt; MIN_AMPLITUDE):
        note = getNote(getFrequency(sig))
        if(note == notes[idx]):
            sys.stdout.write(words[idx])
            sys.stdout.flush()
            idx += 1