Audio

Word of Mouth

These days, I seem to watch more movies on planes than anywhere else. Although an enjoyable distraction, this is way different from the normal movie theater or home theater experience. I am not sure if the films on flights are specially mixed for this form of viewing and environment; I suspect not, but they serve a purpose and my expectations are not particularly high. As long as I can hear the dialog, I am happy. If a few sound effects are thrown in for good measure, that’s a bonus…as long as they don’t screw up the dialog.

A good pair of noise-canceling headphones is a must for this type of movie viewing, if only to attenuate the constant chatter of your fellow travelers in the row behind or, worse still, their bawling children. (Not that I have anything against children; your own are quite different, uniquely special and, of course, remarkably talented compared to the rest in the world, but other people’s should not be invading my avian space.)

So, back to the movie. Having managed to work out the logic of the AV control system, which often appears to have been programmed by someone more familiar with programming reverse Polish logic calculators than user-friendly GUIs, and set the noise canceling headphones to maximum obliterate, then it’s all systems go. Sometimes, the experience is such that it makes me go out and buy the DVD when I get home so I can enjoy the effects that have either been lost, or interfered with the dialog. Almost universally in movies, the dialog is sent to the center channel and the effects are panned into the left and right surround channels. This works well in a movie theater or home cinema, but not so great on headphones where there is no center channel.

Yes, there is a phantom center image, but that is created from equal signals being provided in the left and right channels, but these are the effects channels, of course. Equally, for most people, the center image appears inside the head, i.e., it is not externalized as in the real world or the movie theater experience. Not only that, but the sounds are also spectrally different and arguably may produce a difference in perceived intelligibility. With something like 80% of movies now being viewed on iPads or laptops and tablets (or aircraft LCDs) and listened to on headphones/earphones, perhaps it is time for the movie industry to recognize this and produce releases mixed especially for this market.

This doesn’t have to mean that there has to be a host of different DVDs for the same movies released with different audio tracks, but appropriate coding can be hidden in the audio metadata to enable a mix optimized for a headphone listening to be heard. However, this will require more than just providing the center channel mixed equally left and right with some effects and surround mixed hard right and left, although that would be a good start.

The spectral balance will also have to be corrected not only for headphone listening but center channel versus phantom image perception, as well. Providing the “correct” spectral balance for headphone listening raises an interesting point: What should this be? Whereas it is now pretty clear beyond any reasonable shadow of a doubt that loudspeakers should produce a flat response, smooth off-axis responses together with a smooth acoustic power output characteristic, there is no such consensus or industry standard when it comes to headphones.

Take half a dozen pairs of “rated” headphones and you will measure six completely different response curves; there simply is no standard. However, recent research by Sean Olive and his perception team at Harman is coming up with some interesting data and putting some science into the subject. The problem, though, is compounded by the fact that the perceived frequency response of a pair of headphones is very much dependent on how they are worn and the physical characteristics of the listener’s ears.

Dialog perception, of course, is not just an issue for headphone listeners. Oh no, far from it! Many home theater systems are so poorly set and calibrated such that the surrounds and left/right channels often obliterate or interfere with the perception of the center dialog channel. You really do need to set these systems up correctly, but I suspect that many do not. Indeed, this has become a major selling point for some of the TV “sound bar” systems that produce left, center and right channels in a fixed format and balance. Many people have reported these systems as being more intelligible, apparently because the balance between the channels is better, and less dialog masking occurs.

The foregoing assumes, of course, that the movie sound track is intelligible to start with. Recently, this may not have been the case because there have been numerous complaints concerning some films and TV productions. Two classic cases are The Counselor and Interstellar, with many people being given their money back after seeing the latter film due to the ferocity and justification of their complaints.

Here it was not so much the fault of the dialog editor and sound recording team but the desire of the film’s director not to hear the dialog clearly at times during the film. (I guess, if you own a gasoline-driven car and want to fill it with diesel, then that is your right! But then to hire it out to other people is another matter.) A further issue that the film and TV industry should be aware of is that some 10 to 14 % of the population have less than perfect hearing and would benefit from some form of hearing aid or hearing assistive device. These people are moviegoers and TV viewers just like the rest of the population, except that they suffer even more from poor dialog production.

Roll on the age of Object Based Broadcasting (OBB), where the viewer should potentially be able to adjust the mix to his or her taste/hearing requirement. BYOD in cinemas and movie theaters could soon be a new and growing trend as the paying public finally gets its say in what they want to hear and the level at which they want to hear it (don’t get me started on the movie soundtrack loudness wars!).

For those of you who want to understand more about this topic and want to ask some of the sound recordists and sound editors face to face why they do what they do to the audio content of films and TV programs, why not come along to the AES “The Future of Audio Entertainment Technology” conference being held in Los Angeles in March, and find out for yourself. I will be there, posing some of the questions I have raised here and a lot more besides, as well as giving a tutorial on intelligibility in audio entertainment. (For more information, go to aes.org/conferences/57.)

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