Stereo principles were understood by 1931 but waited decades for commercialization.

Evidence

In 1930s the essential principles by which the missing directional and spatial elements could be communicated were understood, but there were technical and cost limitations to what was practical. It is humbling to read the wisdom embodied in the Blumlein-EMI patent (Blumlein, 1933) applied for in 1931 describing 2-channel stereo techniques that would wait 25 years before being popularized. It is especially interesting to learn that the motivation for stereo came in part from a desire to improve cinema sound (Alexander, 1999, pp. 60, 80). Cinema played a central role in the development of present-day incarnations of multichannel audio and now immersive audio. — Toole, Floyd E, Sound reproduction- the acoustics and…, 385

Categorization

• XREF: The delayed-adoption pattern of stereo echoes the copyright-holders’ resistance described in The Library regarding print technology adoption.