Understanding and Crafting the Mix

The Art of Recording

William Moylan

• Publisher: Routledge
• Year: 2014
• ISBN:
  9781135017170
• Edition: 3
• Topic: Technology & Engineering
• Subtopic: Acoustical Engineering
• Index: Technology & Engineering

Understanding and Crafting the Mix, 3 rd edition provides the framework to identify, evaluate, and shape your recordings with clear and systematic methods. Featuring numerous exercises, this third edition allows you to develop critical listening and analytical skills to gain greater control over the quality of your recordings. Sample production sequences and descriptions of the recording engineer's role as composer, conductor, and performer provide you with a clear view of the entire recording process.

Dr. William Moylan takes an inside look into a range of iconic popular music, thus offering insights into making meaningful sound judgments during recording. His unique focus on the aesthetic of recording and mixing will allow you to immediately and artfully apply his expertise while at the mixing desk. A companion website features recorded tracks to use in exercises, reference materials, additional examples of mixes and sound qualities, and mixed tracks.

Part One Defining the Art of Recording: The Sound Characteristics and the Aesthetic Qualities of Audio Recordings

1 The Elements of Sound and Audio Recording

DOI: 10.4324/9780203758410-1

Audio recording is the recording of sound. It is the act of capturing the physical dimensions of sound and then reproducing those dimensions. The dimensions are reproduced either immediately or from a storage medium (magnetic, vinyl, electronic, digital), and thereby returning those dimensions to their physical, acoustic state.

Audio recording is a process that transforms sound from its physical acoustic state, through the recording/reproduction chain, and back to physical sound.

The “art” of recording emerges with the artistically sensitive application of the recording process. The recording process is being used to shape or create sound as an artistic statement (piece of music), or supporting artistic material. To be in control of crafting the artistic product, one must be in control of the recording process, be fluent in the ways the recording process modifies sound, and be skilled in executing well-defined creative ideas.

These all closely involve interaction with sound. Inconsistencies between the various states of sound are present throughout the audio-recording process. Many of these inconsistencies are the result of the human factor: the ways in which humans perceive sound and interpret or formulate its meanings. In order for the artist (audio engineer/recordist) to be in control of the artistic processes they must understand the substance of their material: sound, in all its inconsistencies.

The States of Sound

In audio recording, sound is encountered in three different states. Each of these three states directly influences the recording process. These three states are:

1. Sound as it exists physically (having physical dimensions);
2. Sound as it exists in human perception (psychoacoustic conception): sound perceived after being transformed by the ear and interpreted by the mind (the perceived parameters of sound being human perceptions of the physical dimensions); and
3. Sound as idea: sound as an abstract or a tangible concept, as an emotion or feeling, or representing a physical object or activity (this is how the mind finds meaning from its attention to the perceived parameters of sound); sounds as meaningful events, capable of communication, provide a medium for artistic expression; sounds hereby communicate, have meaning.

The audio-recording process ends with sound reproduced over loudspeakers, as sound existing in its physical state, in air. Often the audio-recording process will begin with sound in this physical state, to be captured by a microphone.

The recordist—the person making the recording—and all others involved in the industry listen to the sound in all facets of the audio-recording process. They evaluate the audio signal at all stages while the recording is being made. This, of course, results in the recording that is heard by the end listener, and is the reason for making the recording. In the listening process we translate the physical dimensions of sound into the perceived parameters of sound through the listening process (aural perception).

This translation process involves the hearing mechanism functioning on the physical dimensions of sound, and the transmission of neural signals to the brain. The process is nonlinear and alters the information; the hearing mechanism does not produce nerve impulses that are exact replicas of the applied acoustic energy.

Certain aspects of the distortion caused by the translation process are, in general, consistent between listeners and between hearings; they are related to the physical workings of the inner ear or the transfer of the perceived sounds to the mind/brain. Other aspects are not consistent between listeners and between hearings; they relate to the listener's unique hearing characteristics and their experience and intelligence.

The final function occurs at the brain. At a certain area of the cortex, the neural information is processed, identified, consciously perceived, and stored in short-term memory; the neural signals are transferred to other centers of the brain for long-term memory. At this point, the knowledge, experience, attentiveness, and intelligence of the listener become factors in the understanding and perception of sound's artistic elements (or the meanings or message of the sound). The individual is not always sensitive or attentive to the material or to the listening activity, and the individual is not always able to match the sound to their previous experiences or known circumstances.

Figure 1.1 Three states of sound: in air, in perception, as message.

Sequentially, the physical dimensions (1) are interpreted as perceived parameters of the sound (2). The perceived parameters of sound (2) provide a resource of elements that allow for the communication and understanding of the meaning of sound (and artistic expression) (3).

The audio-recording process communicates ideas, and can express feelings and emotions. Audio might take the form of music, dialog, motion-picture action sounds, whale songs, or others. Whatever its form, audio is sound that has some type of meaning to the listener. The perceived sound provides a medium of variables that are recognizable and have meaning when presented in certain orders or patterns. Sound, as perceived and understood, becomes the resource for creative and artistic expression. The artist uses the perceived parameters of sound as the artistic elements of sound, to create and ensure the communication of meaningful (musical) messages.

In the next section the individual states of sound as physical dimensions and as perceived parameters will be discussed individually. The interaction of the perceived parameters of sound will follow the discussion of the individual parameters. These discussions provide critical information for understanding the breadth of the “artistic elements of sound” in audio recording, presented in the next chapter.

Physical Dimensions of Sound

Five physical dimensions of sound are central to the audio-recording process. These physical dimensions are: the characteristics of the sound waveform as (1) frequency and (2) amplitude displacements, occurring within the continuum of (3) time; the fusion of the many frequency and amplitude anomalies of the single sound to create a global, complex waveform as (4) timbre; and the interaction of the sound source (timbre) and the environment in which it exists creates alterations to the waveform according to variables of (5) space.

Figure 1.2 Dimensions of the waveform.

Frequency is the number of similar, cyclical displacements in the medium, air, per time unit (measured in cycles of the waveform per second, or Hz). Each similar compression/rarefaction combination creates a single cycle of the waveform. Amplitude is the amount of displacement of the medium at any moment, within each cycle of the waveform (measured as the magnitude of displacement in relation to a reference level, or decibels).

Timbre

Timbre is a composite of a multitude of functions of frequency and amplitude displacements; it is the global result of all the amplitude and frequency components that create the individual sound. Timbre is the overall quality of a sound. Its primary component parts are the dynamic envelope, spectrum, and spectral envelope.

The dynamic envelope of a sound is the contour of the changes in the overall dynamic level of the sound throughout its existence. Dynamic envelopes of individual acoustic instruments and voices vary greatly in content and contours. The dynamic envelope is often thought of as being divided into a number of component parts. These component parts may or may not be present in any individual sound. The widely accepted components of the dynamic envelope are: attack (time), initial decay (time), initial sustain level, secondary decay (time), primary sustain level, and final decay (release time).

Figure 1.3 Dynamic envelope.

Dynamic envelope shapes other than those created by the above outline are common. Many musical instruments have more parts to their characteristic dynamic envelope, and many instruments have fewer. Further, vocalists and the performers of many instruments have great control over the sustaining portions of the envelope, providing internal dynamic changes to sounds. Musical sounds that do not have some variation of level during the sustain portion of the envelope are rare; the organ is one such exception.

The spectrum of a sound is the composite of all of the frequency components of the sound. It is comprised of the fundamental frequency, harmonics, and overtones, sometimes including subharmonics and subtones.

The periodic vibration of the waveform produces the sensation of a dominant frequency. The number of periodic vibrations, or cycles of the waveform, that repeat its characteristic shape is the fundamental frequency. The fundamental frequency is also that frequency at which the sounding body resonates along its entire length. The fundamental frequency is often the most prominent frequency in the spectrum, and will often have the greatest amplitude of any component of the spectrum.

In all sounds except the pure sine wave, frequencies other than the fundamental are present in the spectrum. These frequencies are usually higher than the fundamental frequency. They may or may not be in a whole-number relationship to the fundamental. Frequency components of the spectrum that are whole-number multiples of the fundamental are harmonics; these frequencies reinforce the prominence of the fundamental frequency (and the pitched quality of the sound). Those components of the spectrum that are not proportionally related to the fundamental we will refer to as overtones. Traditional musical acoustics studies define overtones as being proportional to the fundamental, but with a different sequence than harmonics (first overtone = second harmonic, etc.); this traditional definition is herein replaced by a differentiation between partials that are proportional to the fundamental (harmonics) and those that are not (overtones). This distinction will prove important in the evaluation of timbre and sound quality in later chapters. All of the individual components of the spectrum are partials. Partials (overtones and harmonics) can exist below the fundamental frequency as well as above; they are accordingly referred to as subharmonics and subtones.

Figure 1.4 Harmonic series.

For each individual instrument or voice, certain ranges of frequencies within the spectrum will be emphasized consistently, no matter the fundamental frequency. Instruments and voices will have resonances that will strengthen those spectral components that fall within these definable frequency ranges. These areas are called formants, formant regions, or resonance peaks. Formants remain largely constant, and modify the same frequency areas no matter the fundamental frequency. Spectral modifications will be present in all occurrences of the sound source with harmonics or overtones in the formant regions. Formants can appear as increases in the amplitudes of partials that appear in certain frequency bands, or as spectral components in themselves (such as noise transients caused by a hammer striking a string). They can also be associated with resonances of the particular mechanism that produced the source sound. Formants are largely responsible for shaping the characteristic sounds of specific instruments; they allow us to differentiate between the instruments of different manufacturers, or even to tell the difference between two instruments of the same model and maker.

Listen

to tracks 1 and 2 for the harmonic series played in individual frequencies and pitches, and as a chord.

A sound's spectrum is composed primarily of partials that create a characteristic pattern. This pattern is recognizable as being characteristic of a particular instrument or voice. This pattern of spectrum will transpose (change level but maintain the same distances between frequencies/partials) with every new fundamental frequency of the same sound source and remain mostly unchanged. In this way, this consistent pattern will form a similar timbre at different pitch levels. Formants establish frequency areas that will be emphasized for a particular instrument or voice. These areas will not change with varied fundamental frequency, as they are fixed characteristics (such as resonant frequencies) of the device that created the sound. Formants may also take the form of spectral information that is present in all sounds produced by the instrument or voice.

Figure 1.5 Format regions of two pitches from a hypothetical instrument. Vertical lines represent the partials of the two pitches, placed at specific ...