MKBHD’s Waveform podcast (audio or video) sometimes has a fun “Did they even test this?” section. This week, for the first 12 minutes, the team was ranting about various volume controls – a meandering conversation that I also found just very enjoyable.

The cited answer to “why do a lot of car volume controls max out at 38?” is in a 2021 article from Car And Driver:

But then some research revealed that about 20 years ago, Chrysler decided to try to find the perfect volume interval, one that would result in meaningful difference in sound level without going too far. After much experimentation, they decided that 38 discrete volume settings provided the perfect amount of adjustability—not too fine, not too coarse. So the decree went out across the company that all stereos should go to 38.

However, no citation is given, and I couldn’t find any more information about it.

The one thing the group missed in their discussion is “why even show a number”? I think it helps people in remembering their preference, especially if they share a car with someone else. Remembering that “my volume number is 17” can be helpful, even if it feels a bit clunky.

When volume controls were physical, I believe if they didn’t have a number, they at least had a certain amount of notches so you could remember the nearest notch you liked:

Keynote is an app that could use something like that. At this very moment, I am trying to unify the volume of various clips across slides for an upcoming presentation, and having to use environmental cues like “between Edit Movie below and the rewind button above”: