Are they listening to the music/scene they are recording for? Do they hear themselves or are the headphones designed to cover up their own voices?
Disneyland has a tour for music students called Disney Magic Music Days, and for part of the tour you get to use a music studio backstage and record music to go over a scene from one of their movies. They generally gave us recording headphones. They’re not noise cancelling, because it’s important to be able to hear yourself, generally they give you a metronome beat.
However, this was with a live ensemble, singers who record absent a band (or in separate rooms to avoid microphones picking up other parts) may well be fed the music they’re singing along with.
They’re also often patched in to the sound engineer who is usually in a separate sound-proof room so they can give feedback during/in-between recording sessions without affecting the recording itself. E.G. The engineer could say “a little quieter” and they can instantly adjust instead of having to stop the recording and start another take because the mic picked up the instructions. (IIRC Disney had us patched into the soundboard guy as well, but he was usually fairly quiet because we had a conductor)
They are used to provide the performer with enough context to sing, but avoid bleed into the microphone used to record them.
At its most basic - there is a click track - the metronome. All the way up to the entire backing band - although this would be distracting, but at least a rhythm track. A rap artist would have the appropriate “beats” to rap against. There will be some of the singer’s own voice mixed back into the headphones so that the whole thing sounds reasonably natural, and also allows them to exploit the microphone’s proximity effects whilst hearing the result.
I am a voice actor, I hear my own voice and the voice of the studio engineer, as mentioned upthread. You need to hear your own voice, because as we all know, you sound different when you hear yourself being played back at you than you do in your own head. You get the sound the way it is actually recorded, rather than the sound you think you recorded.
Sometimes I might get additional sounds that I need to react to, like another voice. Or “when you hear [BEEEEEP] put down your pen”. (It could easily be recorded without the beep, but the breathing is more natural with the beep, and it’s so simple to do.)
Sometimes I listen to my own voice, so that I’ll sound the same if we’re recording something for the same thing some time after recording the first part.
I’ve done voice work, and headphones give me a more accurate way to hear my voice as it will sound in the final recording. This way, I can enunciate more clearly, add more intonation, and modify my breathing and rhythm as I need to based on how others will hear me as opposed to the sound of my voice as it resonates through my chest and throat.
Im an audio engineer. The above posts are correct. We create a custom mix for each performer using the pre fader auxiliary sends (we just call em aux sends or cue sends) on the console or in the DAW (digital audio workstation).
a click is common. but we can put anything in there needed to help the artist realize the performance most effectively.
It’s called a “cue mix”, also “monitor” in the US and “foldback” in the UK. In general, it’s whatever the performer wants to hear, to produce his or her best performance.
Most performers use the headphones normally, but some use variations like pulling one headphone cup off the ear so they can also hear their voice naturally. (I think they’re nuts, but whatever works.)
As mentioned above, headphones are used to keep the cue mix from leaking into the microphone. Not only does that make subsequent mixing simpler, but any of the tracks in the cue mix might be replaced later, and you don’t want the ghost of an old replaced piano part in the vocal track.
In most cases, they are listening to themselves, other voice actors, or sound cues.
They need to listen to themselves because they have the ears to pick up when something has gone wrong, and a retake must be done.
A great mic can pick up the slightest sound, and a voice actor has to know it happened.
With a band, the members often get individual mixes of whatever they want. Often the drummer is boosted up so everyone can keep to a common beat. I’ve been to a couple of sessions where they even mixed in a metrnome.