1. Sounds and signals
- A signal represents a quantity that varies in time.
1.1 Periodic signal
- basic form
- sinusoid
1.2. Spectral decomposition
- most important topic
- spectral decomposition
- most important mathematical idea
- DFT
- most important algorithm
- FFT
Discrete Fourier Transform
- takes a signal and produces its spectrum
Fast Fourier Transform
- effiecient way to compute the DFT
1.3 Signal
- offset == radian
- framerate == sample
1.4 Reading and writing Waves
- aplay
- Unix Systems
1.5 Spectrums
- spectrum can apply filter
- low-pass, high-pass, band-stop
1.6 Wave objects
- Signal -> Wave <-> Spectrum
Wave object
- attributes
- ys
- NumPy array that contains the values in the signal
- ts
- array of the times where the signal was evaluated or sampled
- framerate
- the number of samples per unit
- ys
- properties
- start
- end
- duration
