Telecom 346/446 extra-credit programming assignment

Worth up to 7-8 points of exam extra credit.

Write a program that takes a sound file (.wav file) and identifies the 
frequencies it contains in either one or the other (but not both)
of the following senses:

1. Dual-Tone Multi-Frequency (touchtone) encoding: The sound file contains
two tones indicating one of the digits from 0-9 or *,#, as follows:

		1209 Hz      	1336 Hz     	1477 Hz
697 Hz 		1 		2 		3 	
770 Hz 		4 		5 		6 	
852 Hz 		7 		8 		9 	
941 Hz 		* 		0 		# 	

The sound file will contain exactly two sine-wave tones.

2. Musical notes, in the primary octave. The sound file contains
one to three tones, forming a chord, from the octave shown. 
Half-tones (sharps and flats) have been omitted.

C	262 Hz
D	294 Hz
E	330 Hz
F	349 Hz
G	392 Hz
A	440 Hz
B	494 Hz

In case 1, the program should print some analysis information, and 
then an indication of what key was pressed. In case 2, just print 
the analysis information and the notes. 

In each case, construct a set of seven pass-band filters, centered
about each frequency and not containing any adjoining frequencies.
Place the band cutoffs about halfway between each pair of adjacent
frequencies (ie for D, the cutoffs might be 278 and 312).
Run the sound file through each filter. Measure the resultant 
"power level" by finding the average of the absolute value of
the amplitude. The power level should be near zero for absent
frequencies, and much higher for the others.