Fletcher-Munson - Random Variables and You

We have regular discussions about loudness controls, and Fletcher-Munson curves here, so I thought it would be interesting to use that to talk about the problem with testing and human variability.

To simplify, the Fletcher-Munson curve comes from a paper in 1933 which showed that as volume goes down, our hearing changes. It gets worse at the edges and more pronounced int he midrange. A general overview is here:

https://en.wikipedia.org/wiki/Equal-loudness_contour

Now, this is science, and I’m sure they did the best they could, but FM as have the multiple studies after them, have come to different values for these curves (but they agree in principle). What’s worse, the loudness curves are different for front hearing (speakers) than side-hearing (headphones).


Why should we care? Well, these curves are all averages, gathered over samples that are probably not that random. I mean, how many women, how many people over 65, and how many from the Australian outback were tested? Your personal F-M curve I guarantee is different from the curves published by F-M or the studies after. These curves are derived from random samples, they are not indicative of any actual person’s hearing.


So... this means that as we listen to and buy equipment, we need to understand that our own hearing is not like anyone elses. What we are sensitive to, and what we spend money on is different and that’s what it means to be human. For instance, I’m really sensitive to frequency response and room acoustics. I am completely insensitive to absolute phase and phase shift in the speaker.


We are all different and I hope we can all make room for science and engineering as well as the fact that what brings us joy and pleasure of ownership is going to vary a great deal. An average measurement from a study may not tell us a thing about you individually.

Best,

E