Suprise!

soundwave.py: 22 points


At this point, we can finally create full songs. But let’s be real, they don’t sound great. That’s because we are only playing one note at a time. Fortunately, we can play multiple notes at the same time by simply adding, or superimposing, sound waves together.

Since we are adding two SoundWave objects together, this is a perfect time for us to try overloading the + operator. To overload the addition operator, we need to define a __add__() method in our SoundWave class. Specifically, we’ll add a method called __add__(self, s2) to the end of our class definition—Python style suggests always putting methods which overload operators after class-specific methods.

Like the extend() method you created in the previous part, __add__() should take in another SoundWave object, s2, as a parameter. Unlike extend(), however, the __add__() method should create and return a new SoundWave object, and leave the original two SoundWave objects unchanged.

The samples of this new SoundWave object created by the + operator should be the sum (superposition) of the samples of s2 and the samples of self. That is, the i-th sample in the new SoundWave should have a value equal to the sum of the i-th samples of s2 and self:

s.samples[i] = self.samples[i] + s2.samples[i]

Make sure that your program works even when self and s2 have different lengths.

Playing Surprise

To test whether your overloaded __add__() method is working, we have provided a program called surprise.py. Running this program should create a new wave file called surprise.wav that you can play similar to the middlec.wav in the previous part of the lab. If your __add__() method is working, you should hear the start of a song you might recognize…