Some headphone manufacturers tend to put boosts in certain frequencies to make music more pleasurable to the listener. This may work well for bass heavy music to drown out babies when on your next vacation, but it is not a good idea for when you are trying to make executive decisions on the quality of your mix.
If you mix with headphones that boost certain frequencies, you may make decisions that are inaccurate to the actual location that you are in. Even our mixing boards, which come standard with EQ controls to color the sound are usually left completely flat, unless needed for extreme purposes by advanced users. We want a microphone that hears everything as accurately as possible, a cable that doesn’t have any loss, colorization, or interference, a mixer to recorder chain that is flat in response, and finally, a pair of headphones that are as transparent as the microphone.
There are different kinds of headphones that we use. On a cart, I like headphones that completely cover the ears to help isolate as much of the room as possible. This is because on these types of shoots, you have a crew to help do the miscellaneous tasks needed, allowing the sound mixer to sit down and focus solely on the dialogue and the mix.
The most common type of headphone used by sound departments all over the world is the Sony MDR7506. They are considered on the ear type headphones and are pretty flat in their response. They also fold down very small which helps when shoving them into a backpack. It seems like a lot, but I generally purchase a new pair every year, demoting the older pair to be used for Video Village Listeners.
Sometimes when working on certain productions, it will be difficult to isolate the sound of the event from what is being recorded. If you are working in arenas for sports or a fight of the night type of event, you need to think differently in terms of listening options. These are very difficult jobs because you will find yourself cranking levels (especially the headphone levels) that can not only hurt your mix, it can damage your ears. Instead, use something like the Remote Audio High Noise Headset (HN7506). This headphone is not noise cancelling, it is noise isolating and helps to block the bleed of the arenas into your headphones so you can turn down your mix to a safer level.