Center for Computer Research in Music and Acoustics

Stanford University

Amplitude/Gain/Level/Magnitude/Loudness, etc.

Sounds with a pitch (sine wave and harmonic/inharmonic sounds)

Sounds without a pitch (noise and impulse)

More on the concept of frequency, period and wavelength

Frequency and notes

More on harmonics: https://en.wikipedia.org/wiki/Harmonic

More on Fourier series: https://en.wikipedia.org/wiki/Fourier_series

A microphone can be used to convert mechanical pressure waves to an electric analog signal and a speaker can be used to do the opposite.

Analog signals storage, processing and synthesis

From analog to digital: sampling

Waveform of an analog signal to digitize

Sampled waveform

- Sample rate/sampling frequency
- Bit depth

Sampling rate, Nyquist and aliasing

- Typical sampling rate (fs) for audio is 44.1KHz
- Nyquist frequency is at fs/2

Signal reconstruction

Typical audio bit depths are 16, 24 or 32 bits

Digital audio signals range and clipping

x(x) ∈ [-1.0,1.0]