Video lectures about audio technology
The first video is a short introduction to sound reproduction in small spaces (typical rooms) by Floyd E. Toole. Why the traditional on-axis frequency response measured in an anechoic chamber is insufficient for representing the tonal characteristics of loudspeakers? Loudspeaker directivity (DI, polar response) as a key concept presented here. Dr. Floyd E. Toole also has a book "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" (Amazon link) - a reference in room acoustics.
There is a huge amount of misleading information on the net about how digital audio works. There is no question that the main source of the misconceptions is the false high resolution audio marketing. A short video from Xiph.Org reveals the truth about pulse-code modulation (PCM). The video is easy to understand and sampling, quantization (bit-depth) and dither is demonstrated on real equipments. The point is that the output of a properly dithered and filtered digital system is indistinguishable from a band-limited pure analog system with the same noise floor. Digital systems are free from timing errors and modern DACs (digital to analog converters) have no stairsteps in their waveform. (Click on the image to play the video.)
The next video is an introduction to loudspeakers (speaker drivers): a quick journey from the basics to the Thiele-Small parameters. This video is the first part of a longer course.
An interesting demonstration of wave propagation and the similarities of wave behavior from 1959.