Reference is not preference

November 27th, 2010

If you’ve ever done an audio calibration of your home theater you are likely familiar with “reference level”, or the volume at which the calibration is performed. Theoretically, you should be listening to all your movies at reference level. However, I have found that most of my customers are shocked when they hear just how loud reference level is.

What is reference level, anyway? Simply put, it is the volume at which the recording was meant to be heard. Meant by who? The people who created the recording. In the case of film, there is a very specific volume that is defined as “reference”. All films are mixed in the studio at this reference volume.

I’ve discovered that most of my customers, left of their own accord, will choose a listening volume 15, 20, and sometimes 30 dB below reference level. How much quieter is that? Every 10 dB is heard by most people as being about half as loud, so that means most people will voluntarily choose a listening volume anywhere from half to one-eighth as loud as the film was intended to be heard!

Is this bad? Not necessarily. But there are two other significant factors that play into this issue.

The first is that the human ear does not hear things the same at different volumes. This is well documented and charted (look up “equal-loudness contours” if you’re interested in learning more), and it can have a dramatic impact on how well someone hears the details in a soundtrack at different volumes. For example, our ears are much less sensitive to bass at lower volumes, so listening to a movie at a lower volume will mean you’ll miss out on some of the low end in the recording. You may remember the “loudness” button on a stereo you had 10 or 20 years ago. That button was a simplistic approach to dealing with this characteristic of human hearing.

The second problem is that I very often observe people listening to their movies in noisy rooms – people talking in the other room, refrigerators or other equipment humming nearby, or other things that raise the ambient noise level (or noise floor) of the room. A high level of ambient noise in the room (a high noise floor) will mask out quieter details in what you are listening to, and this is exacerbated if the volume level is low to begin with.

The end result of these three factors (low volume levels, the human hearing characteristics, and high noise floor) is that many people are completely missing out on an incredible amount of detail in what they listen to. It’s quite a shame, really, as there is so much good stuff to be heard!

Reference vs Preference

How do you reconcile the difference between reference and preference?

First, make sure your audio system is calibrated, either by using the built-in calibration system or by having someone calibrate it. A non-calibrated system can sound harsh, cause excessive listener fatigue, and even be dangerous to the components of the system, particularly the speakers.

Next, start by seeing if you can adjust your preference a bit. Try adjusting the volume by one-third the distance to reference and watching a movie. For example, most modern receivers show “0” (zero) on the volume readout at reference level (when calibrated). If you normally watch with the volume set to -30, try -20. It will be a significant jump in volume, and you clearly should be careful to not exceed the capabilities of your system, but you may find after getting into the movie a few minutes that not only is the volume fairly comfortable, but that you can hear a lot more detail than you could before. Then try another third and watch for a while, and keep going until you hit reference or can’t stand it any more.

Second, and especially if you find that you don’t want to change your volume setting, invest in a receiver with Audyssey Dynamic EQ or Dolby Volume. Both of these technologies are designed to help you hear the detail you might normally miss at lower volumes. Essentially, they compensate for the ways our ears hear things differently when you turn the volume down.

Finally, Audyssey and Dolby can’t do anything about the level of ambient noise in your room, so do what you can to silence anything making noise when you are watching a movie.

And just so you know, I listen to my movies at about -10 to -12 dB from reference on my calibrated system. It’s not reference, but it’s loud, and I like it!

Your preference may not be reference, but with the right techniques you’ll still be able to hear the soundtrack’s essence.

(Sorry, just couldn’t pass that last bit up!)