INTERACTIVE LABS
Interactive labs
No formulas to memorise first. Move the controls, listen to the result, look at the graph, then go back to the lesson to see why.
02Open the lab ↗06Open the lab ↗10Open the lab ↗11Open the lab ↗15Open the lab ↗20Open the lab ↗21Open the lab ↗
Hear frequency and amplitude
Adjust the sound directly and connect what the waveform does with what you hear.
In lesson: How is sound made, and how does it become the line you see in a recording?Sliding window
Watch short-time analysis move step by step along a recording.
In lesson: From a whole recording to a list of comparable numbers: what steps lie in between?Frequency probe and spectrum
Sweep through frequencies yourself, then split a signal apart and put it back together.
In lesson: How does a computer find which high and low components a single curve is made of?Complex numbers and phase
Rotate a phasor and see how its length and angle describe a signal together.
In lesson: How can one number hold both “how strong” and “where it starts”?Choosing a frame length
Change the window length and compare detail in time with detail in frequency.
In lesson: Why a whole-clip spectrum can’t tell when a sound happened: the short-time Fourier transformMel filters and DCT
Go from a spectrum to the MFCCs widely used in machine learning.
In lesson: The four steps one line of code does for you: getting MFCCs in PythonSpectral statistics
Sum up a spectrum with a few numbers, such as its centroid and bandwidth.
In lesson: Squeezing one column of a spectrum into three numbers: band energy ratio, spectral centroid and bandwidth