MattC
Veteran
Mono vs. Stereo
There seems to be some confusion regarding mono and stereo as it relates to what we record and mix for our film projects. I started to respond to this in the thread in which the questions originally came up but then thought it might make more sense to make this a separate post.
How to begin, well the first thing we need to understand what stereo is. Stereo isn’t so much a reality as it is a perception. Sounds, natural ones at least, are not stereo, they are monaural, but we perceive them in stereo. (We actually perceive well beyond “stereo” but I’m not going to get into surround mixing in this post, so for the purpose of this discussion lets assume that “stereo” is as good as it gets.) For example. Let’s say that I stand directly in front of you and clap my hands. The sound waves from the clap reaches each of your ears in the same manner at the same time so you perceive the sound as coming from directly in front of you. If I moved to your right and clapped the sound waves would reach each of your ears at a different time and with a different quality. These differences allow you to tell from where the sound is coming from, they allow you to “place” the sound in the stereo field in front of you. The differences you perceive (because you have to very hi-quality microphones attached to each side of your head) allow you to hear in stereo, but the clap itself is monaural.
So let’s take this a step further. Walk out your door, and stand with your arms out by your sides and sweep them in front of you. This is your “stereo field”. Now, close your eyes and listen (people just don’t listen enough). You’re going to hear lots of stuff. A bird off to your right, a car driving by from right to left, a car honking on the left. Maybe a conversation taking place a ways away from you to the left but just off center – you get the idea. These are ALL monaural sounds, each of which you perceive in stereo. Based on the relationship of the sound to your ears.
But we record in stereo, right? I mean my cd’s are all in stereo and movies are stereo, so don’t we record in stereo? Not too often, no. We record in stereo either because we need to capture a sound in it’s natural state (ambiance), because it is impractical to record it any other way, or both. An orchestra is a good example of this. It would be impractical to record each instrument separately and, because of how the music is played (very large group led by a conductor and the requirement to hear each other in order to blend with your section) makes this impractical. It is also undesirable, since the sound of one of the most important instruments, the concert hall itself, would be missing. So we set up two mikes, to imitate how we hear, and we record the whole performance at once. Since the microphones are mimicking our ears the two recordings (recorded at the same time, each to its own stereo “channel”) when played together allow us to perceive the same stereo effect we would have perceived had we been standing in the hall at the time of the recording.
This is different from how most rock bands or pop groups are recorded (unless the are recorded live). In this setting we would record each instrument individually usually in mono. One possible exception to this is drums were they might be recorded as a set in stereo, although more than likely they will mike each drum serperatley and then mix the set together. So no we have a whole band recorded (drums, bass, guitars, piano, vocalist) and each track is mono. How do we get stereo? Well the sound engineer gives it to us and he uses two main tools to do this: panning and reverb. Panning allows us to move a sound from one speaker to the other. If we pan hard left, the sound will only come out of the left speaker and it will sound as if it is coming from our left, panning hard right will achieve the opposite result. If we pan at say, 45 degrees to the left, the sound will be mostly coming from the left but some sound will also be coming from the right hand speaker. When we pan we think in degrees relative to our position. So, if I pan a sound to left 45 is will sound as if it is coming from a spot 45 degrees to my left. If we pan a sound to 0, or center, it will sound as if the sound is directly in front of us, even if the speakers are spaced far apart. The sound engineer “places” the sound in the stereo filed by panning it left and right so that it matches what the audience should be experiencing. The only exceptions to this are dialog, which is almost always panned center, and foley pertaining to the character who is speaking (it would be very odd to hear the characters voice coming from the center of the stereo field as his footsteps moved from right to left). So panning gives us direction and reverb gives us distance. When we combine the two we can place a sound anywhere in the stereo field.
So why do we do this? Why is it good to deal with lots of small mono recordings instead of larger stereo recordings? Well it gives us much more control over the mix. Ideally every sound should occupy its own space in the mix. This doesn’t always work in the purest sense, but that’s what we shoot for, every sound in its place and this includes position and/or frequency if possible. For example a bass drum and a bass are often both panned center, but then they get muddied so we cut or boost frequencies from each so that they both “sit in the mix”. This principal applies to all sound design, whether music or picture. The resulting mix, even though it is comprised of all mono source recording, is stereo.
How do our camcorders record? Well it depends on the mic and each cameras recording potential, but if we are using a mono mic, we are recording mono. If we use a mono mic and we record the signal to two channels, we don’t have stereo, we simply have the same mono signal on two signals, which when played through two stereo speakers will make the sound appear to come from directly in front of us. This is fine for dialog. If you find that your dialog has been recorded to only one channel of a stereo pair, you can simple copy the waveform into the other channel. In an audio app, you would simply pan the signal to the center.
Sometimes we will record ambient sound in stereo, but often that gets recorded as mono as well. We use that sound as a canvass and paint in the additional colors of sound throughout the stereo field. There are also ways to fake a stereo signal from a mono signal, to make it wider and provide more space for other sounds to sit in the mix, but that’s a post unto itself.
Hope this has helped.
Matt
There seems to be some confusion regarding mono and stereo as it relates to what we record and mix for our film projects. I started to respond to this in the thread in which the questions originally came up but then thought it might make more sense to make this a separate post.
How to begin, well the first thing we need to understand what stereo is. Stereo isn’t so much a reality as it is a perception. Sounds, natural ones at least, are not stereo, they are monaural, but we perceive them in stereo. (We actually perceive well beyond “stereo” but I’m not going to get into surround mixing in this post, so for the purpose of this discussion lets assume that “stereo” is as good as it gets.) For example. Let’s say that I stand directly in front of you and clap my hands. The sound waves from the clap reaches each of your ears in the same manner at the same time so you perceive the sound as coming from directly in front of you. If I moved to your right and clapped the sound waves would reach each of your ears at a different time and with a different quality. These differences allow you to tell from where the sound is coming from, they allow you to “place” the sound in the stereo field in front of you. The differences you perceive (because you have to very hi-quality microphones attached to each side of your head) allow you to hear in stereo, but the clap itself is monaural.
So let’s take this a step further. Walk out your door, and stand with your arms out by your sides and sweep them in front of you. This is your “stereo field”. Now, close your eyes and listen (people just don’t listen enough). You’re going to hear lots of stuff. A bird off to your right, a car driving by from right to left, a car honking on the left. Maybe a conversation taking place a ways away from you to the left but just off center – you get the idea. These are ALL monaural sounds, each of which you perceive in stereo. Based on the relationship of the sound to your ears.
But we record in stereo, right? I mean my cd’s are all in stereo and movies are stereo, so don’t we record in stereo? Not too often, no. We record in stereo either because we need to capture a sound in it’s natural state (ambiance), because it is impractical to record it any other way, or both. An orchestra is a good example of this. It would be impractical to record each instrument separately and, because of how the music is played (very large group led by a conductor and the requirement to hear each other in order to blend with your section) makes this impractical. It is also undesirable, since the sound of one of the most important instruments, the concert hall itself, would be missing. So we set up two mikes, to imitate how we hear, and we record the whole performance at once. Since the microphones are mimicking our ears the two recordings (recorded at the same time, each to its own stereo “channel”) when played together allow us to perceive the same stereo effect we would have perceived had we been standing in the hall at the time of the recording.
This is different from how most rock bands or pop groups are recorded (unless the are recorded live). In this setting we would record each instrument individually usually in mono. One possible exception to this is drums were they might be recorded as a set in stereo, although more than likely they will mike each drum serperatley and then mix the set together. So no we have a whole band recorded (drums, bass, guitars, piano, vocalist) and each track is mono. How do we get stereo? Well the sound engineer gives it to us and he uses two main tools to do this: panning and reverb. Panning allows us to move a sound from one speaker to the other. If we pan hard left, the sound will only come out of the left speaker and it will sound as if it is coming from our left, panning hard right will achieve the opposite result. If we pan at say, 45 degrees to the left, the sound will be mostly coming from the left but some sound will also be coming from the right hand speaker. When we pan we think in degrees relative to our position. So, if I pan a sound to left 45 is will sound as if it is coming from a spot 45 degrees to my left. If we pan a sound to 0, or center, it will sound as if the sound is directly in front of us, even if the speakers are spaced far apart. The sound engineer “places” the sound in the stereo filed by panning it left and right so that it matches what the audience should be experiencing. The only exceptions to this are dialog, which is almost always panned center, and foley pertaining to the character who is speaking (it would be very odd to hear the characters voice coming from the center of the stereo field as his footsteps moved from right to left). So panning gives us direction and reverb gives us distance. When we combine the two we can place a sound anywhere in the stereo field.
So why do we do this? Why is it good to deal with lots of small mono recordings instead of larger stereo recordings? Well it gives us much more control over the mix. Ideally every sound should occupy its own space in the mix. This doesn’t always work in the purest sense, but that’s what we shoot for, every sound in its place and this includes position and/or frequency if possible. For example a bass drum and a bass are often both panned center, but then they get muddied so we cut or boost frequencies from each so that they both “sit in the mix”. This principal applies to all sound design, whether music or picture. The resulting mix, even though it is comprised of all mono source recording, is stereo.
How do our camcorders record? Well it depends on the mic and each cameras recording potential, but if we are using a mono mic, we are recording mono. If we use a mono mic and we record the signal to two channels, we don’t have stereo, we simply have the same mono signal on two signals, which when played through two stereo speakers will make the sound appear to come from directly in front of us. This is fine for dialog. If you find that your dialog has been recorded to only one channel of a stereo pair, you can simple copy the waveform into the other channel. In an audio app, you would simply pan the signal to the center.
Sometimes we will record ambient sound in stereo, but often that gets recorded as mono as well. We use that sound as a canvass and paint in the additional colors of sound throughout the stereo field. There are also ways to fake a stereo signal from a mono signal, to make it wider and provide more space for other sounds to sit in the mix, but that’s a post unto itself.
Hope this has helped.
Matt
