I remember the first time I experienced it. I was driving a rented Pontiac Sunfire. As I accelerated to merge onto the highway, I noticed the volume on the radio getting louder. Interesting. It got quieter when I slowed down. This intrigued me… the idea that the car can adjust the output volume of audio depending on the environment.
Except, in this case, it’s fairly simple adjustment only dependant on the speed of the car.
I experienced this again this past week with a rental car. Now, it’s fairly aggravating. Why? It adjusts for speed only and makes the change in volume jarring.
Sound follows a power law. If you double the power, it can sound four times louder. Going fast doesn’t necessarily mean the car is louder. Cars, especially the one I rented, can be relatively quiet on a highway.
What I’ve had to do is adjust the volume down after the car accelerates and then have to adjust it up after it decelerates. This is frustrating.
Other factors, like people talking in a car, the fan running, outside noise, etc, can affect the perception of sound. Since people can block out these noises differently, it’s better to allow them to adjust the volume on their own… or at least limit the automatic gain adjustment.