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Mixing

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Introduction

•  Audio mixing is used for sound recording, audio editing and sound systems to balance the relative volume, frequency and dynamical content of a number of sound sources. Typically, these sound sources are the different musical instruments in a band, the sections of an orchestra, announcers and journalists, crowd noises etc.

•  Sometimes audio mixing is done live by a sound engineer or recording engineer, for example at rock concerts and other musical performances where a public address system (PA) is used.

•  A typical concert has two mixers, one located in the audience to mix the front of house speakers heard by the audience and the other located at the side of the stage, mixing for the monitor speakers positioned directly in front of the performers so that they can hear one another.

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Introduction

•  Another example of live audio mixing is a DJ mixing two records together. Break beats are created by mixing between identical breaks. Often the end of one pre-recorded song is mixed into another so that the transition is seamless, which is done through beat-matching or beat-mixing and possibly pitch control.

•  At other times, audio mixing is done in studios as

part of a multitrack recording in order to produce digital or analog audio recordings, or as part of an album, film, or television program.

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Introduction •  In film/video projects, the Mixers must balance the

various elements: •  Dialogue (and ADR), •  Music, •  Sound Effects and •  Foley Effects •  The Dialogue Mixer/Lead Mixer or Gaffing Mixer

commands the mixing stage; •  There are also Effects Mixer, Music Mixer and Foley

Mixer. •  On huge pictures with tight deadlines, it is possible

that several teams of mixers are working simultaneously on numerous stages in order to complete the mix by the release date.

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A Good Mix •  A good mix often goes unnoticed. When all tracks

are balanced correctly, nothing sticks out and nothing is hidden.

•  Some engineers have a clear idea of what they want the mix to sound like, while others may not.

•  By knowing what to listen for, you can improve your artistic judgments during recording and mixdown.

•  To train your hearing, analyze recorded sound into its components and concentrate on each one in turn.

•  It is easier to hear sonic flaws if you focus on a single aspect of sound reproduction at a time.

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Tonal Balance The overall tonal balance of a soundtrack should not be too bassy or trebly. This means should not have an imbalanced emphasis on low or high frequencies. Emphasis of any one frequency band over the other would eventually cause listening fatigue.

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Spatial Positioning •  A good stereo mix would recognize that there is more

to positioning than just left and right. •  Tracks should be panned to many points across the

stereo field. •  Try to achieve a stereo stage that is well balanced

between left and right. •  If you want the spatial positioning to be realistic, the

reproduced sound should simulate the spatial layout of the actual recorded elements. For example, if your video shows a car on the far right of the frame, you might want to pan the car’s sound effects to the right.

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Sense of Depth •  To achieve a sense of depth in a soundtrack, there should be a

blend of presence and spaciousness. •  Presence is the apparent sense of closeness to the sound

source. •  It is achieved by close miking, overdubbing and using

microphones with a presence peak or emphasis around 5kHz. Using less reverb and effects can also help.

•  To mimic the closeness of a cat shown visually, the ‘mewing’ sounds should be captured with a close mic and no reverb added.

•  Spaciousness is a sense of air around the reproduced sounds. Without air or ambience, the sound elements may seem isolated or too close to the listener.

•  To achieve spaciousness, try recording in stereo, miking farther away or adding reverb in post-production.

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Realism •  A good soundtrack mix would be one that is an accurate

reproduction of the actual sound elements. •  •  To achieve a realistic tonal balance in your mix, it is important for

you to critically listen to the natural balance of the sounds in real life.

•  Observe the tonal balance in professional films and notice how natural all these sounds blend.

•  Realism in spatial positioning is to place your sounds in the stereo field according to where they occur in the visual field.

•  If a scene is set in a cathedral, expect to apply a ‘cathedral reverb’ on your close-miked sounds so that they reproduce the expected reverberant sound of a cathedral.

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Mixing in Different Contexts 1

Music

- Instruments are evenly or naturally spaced in the stereo image - Lead elements like a lead singer should be clear enough though still well-blended in the mix - Good tonal balance of frequency bands - Adequate use of dynamic range to enhance musical expression e.g. contrast of soft and loud sections.

Too narrow or wide spatial positioning with audible ‘holes’ in the stereo image - Lead elements are not able to be heard above other instruments - Over-emphasis of any frequency band e.g. too bassy - Causes ear fatigue due to unchanging dynamics.

Good Mix Bad Mix

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Mixing in Different Contexts 2

Radio

- Announcer or narrator must clearly be the in the foreground. - Dynamic range should be relatively small - Voice and music blend seamlessly without periods of silence

- Vocal elements are hidden behind other sound elements - Dynamic range is too wide; listeners either strain to hear soft sounds or are shocked with sudden increases in volume. - Unnecessary periods of silence

Good Mix Bad Mix

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Mixing in Different Contexts 3

Film

- Useful manipulation of spatial positioning - Vocal elements are clearly heard above other sounds. - May utilize a wide dynamic range to enhance dramatic aspect of the visuals

- A mix that does not adequately utilize stereo imaging. - Dialogue or speech is muffled behind other audio. - Narrow dynamic range that causes ear fatigue.

Good Mix Bad Mix

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Mixing in Different Contexts 4

Video and Television

- Dynamic range should be relatively small - Mix must be mono-compatible i.e. must be acceptable when heard through mono speakers - Vocal elements should stand out from backing material.

- A mix that includes extreme volume levels; soft sounds are too soft while loud sounds are too loud. - The mix sounds imbalanced in mono; due to exceptionally-wide stereo image or phase cancellation - Vocal elements are overpowered by other sounds.

Good Mix Bad Mix

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Exceptions in Mixing •  As in any creative domain, there are exceptions to the standard rules of

what makes a good mix. However, these exceptions are well-thought and used with the intention of creating heightened attention.

•  For example, when the main character on screen is being overwhelmed

with emotion, you might choose to create a muffled mix where other voices or sounds are unclearly layered on top of each other.

•  Also, you might prefer to bring the volume of your soundtrack above all

these voices and sounds. Although this defies the mixing rule that requires dialogue to be clearly audible, this is a calculated move to put the audience in the shoes of the main character by highlighting the sense of overcoming emotions and the natural tendency to lose focus on one’s surroundings.

•  An important note is that to defy conventions, you must first be well-informed of these rules and be able to justify the need to oppose them.

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Mix Automation •  In Pro Tools, you can use dynamic automation of mixing

controls on each of the track types. You can write automation moves and view them in real time during playback of your session.

•  As you mix a soundtrack, you might adjust the mixer controls several times. An automated mixing system can remember your mix moves and later recall and reset them accordingly each time you play back the mix.

•  Automated mixing has many benefits. You can: •  Perform complex mixes without errors. •  Fine-tune the mix moves. •  Recall mixes weeks or months after storing them, without

having to reset the mixer manually each time. •  Listen to the mix without the distraction of having to adjust

faders.