Week 5

This week we will focus on the concept of groove in the theory track, and get to know concepts like “offbeat”, “upbeat”, “downbeat”.

In the terminology track you will learn more about gestures and the term coarticulation.

In the methods track you will get an overview of how it is possible to analyse motion from ordinary video recordings. Remember to use the dictionary.

5.4 A Discussion on Groove

In this article we will explore the term groove as a noun and as a verb.

As a noun, groove generally indicates a certain part of an overall musical sound, mix, or arrangement. Allan Moore places the groove in what is “laid down by the bass and drum kit” (2001:34). This is not a definition, but it does reveal a common point of view about the most relevant instruments.

Vijay Iyer suggests that the groove

might be described (but not defined) as an isochronous pulse that is established collectively by an interlocking composite of rhythmic entities (Iyer 1998).

Though the groove�s relationship to the steady (isochronous) pulse seems rather vague in Iyer�s description, it certainly shows the link to a set of rhythmic components. But which ones?

Timothy S. Hughes writes,

A figure is not a groove unless it is designed to be repeated (2003:14).

The expectations created by repetition are vital in this respect. (see Danielsen 2006, chap. 8, and Hawkins 2008 for discussions of repetition). Solitary rhythmic events might affect the groove but do not contribute to any recognizable structure for it, which is important for the groove to be established.

Another central question: Does the groove in fact have to be established collectively, or can a single instrument (or sound source) supply it? When a sole bass drum sound booms out of the speakers in a club, and the crowd starts moving, is this a groove? This question raises the issue of the aesthetic qualities often linked to the term. Referring to Charles Keil and Steven Feld’s 1994 book Music Grooves, Iyer writes,

Groove involves an emphasis on the process of music-making, rather than on syntax . . . The focus is less on coherence and the notes themselves, and more on spontaneity and how those notes are played (Iyer 1998).

Like Keil and Feld, Iyer favours for his vision of groove the interaction of a group of musicians playing live, and the inevitable “miniscule, subtle microtiming deviations from rigid regularity” that follows (ibid).

Two further questions arise here: Are grooves only to be related to live musicians? And do grooves require deviations from rigid regularity? A recording of live musicians undeniably preserves groove relations, so the first question is less concerned with the actual presence of musicians than with some sense that the music is being played “live,” either in concert or on a recording. But surely music production techniques like multitrack recording, overdubbing, quantization, editing, and the use of drum machines, sequencers, and other types of electronic music equipment are also tools for the production of grooves, at least when they are used in a “groove”-preserving manner.

This leads to the second question. The performance ideal of playing as “tight” as possible according to the studio�s “click track” arose in many pop genres during the 1970s, especially around disco music. During the 1980s, sequencers and drum machines maximized this “tightness” while creating the expectations later to surround electronic dance music and its body movement. The use of electronic equipment is especially efficient for producing the machine-precise timing that is seen as appropriate for this genre. But the very same equipment and techniques are also used in other genres with very different ideals of “tightness.” Ultimately, while deviations from rigid regularity are certainly central to many genres of groove-based music, they should not be considered a prerequisite or universal quality of a groove.

Rather, grooves and what should be considered their vital musical elements should chiefly be seen in connection to body movement. Certain basic rhythmic pulse-oriented elements of a groove may facilitate a basic movement pattern while other sounds, appearing between the downbeats and upbeats or atop them, shape this pattern or even suggest alternatives to it (various body parts can move simultaneously to different pulses). Thus all recurring sounds that take part in this process should be considered elements of the groove.

MUSIC GROOVES

When “groove” is used as a verb, an adjective, or an adverb, it has an aesthetic connotation. In this form, several scholars have expressed similar notions regarding qualities related to grooves, in terms of both how they are reacted to and how they are produced.

The Norwegian musician and music researcher Carl Haakon Waadeland discusses the quality of “swing,” a term typically associated with jazz music, that has definite parallels to “groove”:

Swing is conceived as a quality of music performance, related to a process through which the musicians, both individually and in an interactive context of playing together, make a musical phrase � a rhythm or a melody � �come alive� by creating a performance that in varying degrees involves playing �against� a �fixed pulse� (Waadeland 2001:23; emphasis in original).

Turning to the music listener and the experience of swing, he continues:

When exposed to music that we perceive as swinging, we often want to tap our foot, clap our hands, move our body, or, perhaps, dance to the music. In this way we experience how swinging and “groovy” music initializes “energy” and generates movements in our body, thus, various body movements may be seen as a consequence of an experience of swing (loc. cit.; emphasis in original).

Waadeland then extends this type of experience to comprise Western classical music (Bach, Stravinsky, a Vienna waltz), Brazilian samba, and Norwegian folk music, where every performance must swing “in its own specific way” (ibid.: 24; emphasis in original).

These perspectives on how swing is produced and received are in line with Keil�s notions of swing and groove:

It is the little discrepancies within a jazz drummer�s beat, between bass and drums, between rhythm section and soloist, that create �swing� and invite us to participate (Keil 1987:277).

Keil also argues that participatory discrepancies are present through the use of various types of sound production equipment and effects, including “space, echo, reverb, digital delay, double-tracking” (ibid.: 282). Such effects can introduce important dimensions to a track, but for groove-based popular music, entry points at precise positions, echo- or delay-effects that strengthen exact metrical subdivisions, and the absence of any reverb might be just as important.

“Groove” or “groovy” as a verb or an adjective/adverb is used to express a specific experience with music. The nature of these experiences may not be universal, but in line with Waadeland, one generalization is probably acceptable: the music grooves if body movements are activated by its rhythmic elements. How music is produced or played in order to activate movement varies according to specific cultural traditions to such an extent that the question becomes moot. The contributions of Keil, Iyer, and Waadeland, however profound, do not embrace all groove-based music. There are common features and similarities but also significant differences among the various genres. Why some people move to a certain type of music and others do not reflects the kinds of music to which they were previously exposed. Individual body movements and movement patterns are shaped according to the style of dance music in question, and familiar genres usually work better.

References

5.6 An Analysis of a Dance Music Groove

Electronic dance music has become extremely popular since the 1990s. In the following a groove from the beginning of a typical dance music track is analysed according to the theory presented in this course.

The first four measures (0:06�0:14) of Basement Jaxx�s Jump n� Shout from 1999 is an example of a groove that has a clear communication of the main pulse, but with an additional pattern that makes this beginning more exciting (more groovy!). In the notational representation underneath you can see the bass drum sounds as the lowest staff. The tempo of 127 bpm (2 bass drum sounds per 0.94 seconds) is a good tempo for dancing (and for a fast walk). On the spectrogram beneath the notational representation you can see the bass drum sounds as the largest figures � repeated eight times. Notice that these figures are thinner at the start and fatter at the bottom. This shape is formed by a descending pitch movement that makes the experience of this sound as a downbeat even stronger (Zeiner-Henriksen 2010a:Chap. 8).

Together with the bass drum there is a hi-hat that can be seen at the top staff of the notational representation. This sound has mostly entry points at the off-beat, forming an alteration between the low bass drum sounds and the high hi-hat sounds � a pattern that is very effective in setting a main pulse (see Zeiner-Henriksen 2010b:Chap. 3).

Notation1
Notation1
  • Notational representation of Basement Jaxx�s Jump n� Shout, 0:06�0:14.
image083.png
image083.png
  • Spectrogram of Basement Jaxx�s Jump n� Shout, 0:06�0:10, cymbal pattern circled.

In the middle staff of the notational representation you can see a third rhythmic layer consisting of a cymbal pattern � its attacks are as salient as the hi-hat sounds but not as dominant as the bass drum sounds. You can also see the entry points of this pattern circled in the spectrogram. While the two others communicate the main pulse, this pattern is present to make it more exciting � more groovy. But how does it become more groovy?

If we say that the alternating bass drum and hi-hat pattern activates a steady up-and-down movement (head nodding, upper-body bouncing), then this cymbal pattern interacts with that structure. The third (and seventh) event of the cymbal pattern has the same entry point as the bass drum sound and therefore stresses those downbeats. In this notational representation there is an undulating line that represents a possible movement curve � down on the bass drum sound and up on the hi-hat, and with a slightly lower curve where the cymbal sound has the same placement as the bass drum sound.

image085.png
image085.png
  • Notational representation of Basement Jaxx�s Jump n� Shout, 0:06�0:14, with suggested movement curve.

This up-and-down movement pattern is probably not changed by the cymbal pattern, but our experience of the movement might be altered. Being placed right before the bass drum and hi-hat sounds, they seem to introduce a sort of tension or friction into the groove, making small dents in the movement pattern established by the bass drum and hi-hat. In the notational representation and the spectrogram below these tension points are marked as small bumps in a possible movement curve (an up-and-down movement).

image087.png
image087.png
  • Notational representation of Basement Jaxx�s Jump n� Shout, 0:06�0:14, with suggested movement curve and possible tension points circled.
image089.png
image089.png
  • Spectrogram of Basement Jaxx�s Jump n� Shout, 0:06�0:14, with suggested movement curve and possible tension points circled.

An electronic dance music track often starts out with a build-up section that leads to a more complete groove where there are more interactions between rhythmic patterns. While some of these may be closely connected to and in various ways supportive of the basic beat that communicates the main pulse, other patterns may be more independent and contribute with elements that bring tension, emphasis or various forms of expectation to the groove.

image097.png
image097.png
  • Notational representation of Basement Jaxx�s Jump n� Shout, 0:18�0:21, with possible tension points, emphasized beats and entries producing expectation circled.

The excerpt represented above starts two measures further into the track (measures 7 and 8; 0:18�0:21). Here the hi-hat is boosted in the mix compared to the preceding part (measures 1 to 6). A snare drum joins in with three similar but not identical sounds that interact in yet other ways with the dominant movement pattern. The cymbal pattern is somewhat simplified, probably to avoid colliding with the snare drum pattern.

The first two snare drum events seem to have an effect similar to the cymbal pattern in creating tension or friction in the groove, while the three events ending both of the periods of four beat-cycles seem to function as a pick-up note in relation to the following downbeats, bringing a sense of expectation to that part. The extra snare drum sounds that fall exactly on the upbeats do not seem to have a role beyond somewhat emphasizing this specific beat.

image085.png
image085.png
  • Spectrogram of Basement Jaxx�s Jump n� Shout, 0:18�0:21, with suggested movement curve and possible tension points, emphasized beats and entries producing expectation circled.

Given the track�s tempo of 127 bpm, it may seem like a reach to identify this many influential events. But it is important to distinguish among the various roles that sounds might play in forming a groove that in turn moves the body. There are no right answers or straightforward recipes for good dance music: these roles will influence each other in quite intricate ways, and each dancer will respond differently to them as well. But in aiming to distinguish what makes a good groove, we must allow for all of the possibilities.

References

5.9 Musical Gestures

Gesture has been a buzzword recently, but what is actually a gesture?

There is not only one, precise definition of gesture. In fact, it differs widely. In this article we will discuss its usage and various meanings.

The Oxford dictionary offers a “classic” gesture definition:

a movement of part of the body, especially a hand or the head, to express an idea or meaning

This definition is almost identical to those of other large dictionaries, including Merriam-Webster, Collins and Dictionary. It is interesting to note that all of these definitions focus on three elements:

  • movement of the body
  • in particular, movement of the hands or head
  • expression of an idea/meaning/feeling

The MacMillan dictionary adopts a slightly broader definition:

a movement that communicates a feeling or instruction

Here, “instruction” has been added as part of the definition, and this is also followed up with two sub-definitions:

  1. hand movement that you use to control something such as a smartphone or tablet […]
  2. the use of movement to communicate, especially in dance

Of all of the general definitions of gesture, MacMillan’s resonates best with recent trends in many research communities.

Academic Definitions

As can be expected, there are numerous definitions of gesture in the academic literature. They may be broadly divided into three main categories:

  • Communication: gestures are used to convey meaning in social interaction (linguistics, psychology)
  • Control: gestures are used to interact with a computer-based system (HCI, computer music)
  • Metaphor: gestures are used to project movement and sound (and other phenomena) to cultural topics (cognitive science, psychology, musicology)

The first type of definition most closely resembles the general understanding of the term, as well as the definition that is presented in most dictionaries.

The second type represents an extension of the first, but incorporates a shift of communicative focus from human-human to human-computer communication. Still, the main point is that of the conveyance of some kind of meaning (or information) through physical body motion. In its purest sense, such as finger control on a touchscreen, this type of human-computer communication is not especially different from that of the “gesture” used in human-human communication. Likewise, nowadays most people are accustomed to controlling their mobile devices through “pinching,” “swiping,” etc., so it seems like such “HCI gestures” have become part of everyday language, just as the MacMillan definition suggests.

The third type, on the other hand, focuses on gesture in a metaphorical sense. This is what is commonly used when people talk about the musical gesture.

Musical gesture

Musical gesture has become a popular way to describe various types of motion-like qualities in the perceived sound (such as by God�y) or even in the musical score alone (such as by Hatten). This, obviously, is a long way from how “gesture” is used to evoke a meaning-bearing body motion in linguistics, although it may be argued that there are some motion-like qualities in what is being conveyed in the musical sound as well.

One reason many music researchers embrace the term gesture is because it allows us to make a bridge between movement and meaning. As we have seen previously, movement can be described as the physical displacement of an object in space over time. Meaning, on the other hand, denotes the mental activation of an experience.

The notion of gesture may therefore be argued to cover both movement and meaning, and therefore bypasses the Cartesian divide between matter and mind. As such, the term gesture provides a tool for crossing the traditional boundary between the physical and the mental world. Exactly such a crossing is at the core of the embodiment paradigm and it forms the strength of the current extension from disembodied music cognition to embodied music cognition.

References

5.11 Coarticulation in Music

In this article we look a little more at the concept of coarticulation, meaning the fusion of small-scale actions and sounds into larger units.

The term coarticulation was first coined in linguistics to explain how syllables “merge” into words, which again “merge” into sentences. Professor Rolf Inge God�y and colleagues at the University of Oslo have used the term in a similar way to explain how musical phrases can be seen as the fusion of small-scale sound units into sounds and phrases (melodies).

Our short-term memory is important for how we perceive the world, and also music. Although it is difficult to give an absolute duration, it is common to say that the short-term memory covers a range of about 0.5 to 5 seconds, perhaps longer if there are few events.

Based on the studies of music cognition at the University of Oslo, we believe that action and sound is broken down into a series of chunks in our minds when we perceive or imagine music. These chunks are typically based on the duration of our short-term memory, that is, 0.5 to 5 seconds. Not coincidentelly, this is typically also the duration of many human actions, anything from opening a door, to meaningful snippets of speech, and to many musical phrases.

From a cognitive perspective, it is commonly accepted that when we listen to music we often perceive such chunks (phrases, measures, or motives) rather than shorter or larger units.

Taking these thoughts into an embodied cognitive paradigm, we see that the formation of perceptual chunks can be multimodal in nature, and that chunking can be found also in the sound-producing actions of performers. We will not get into details here, but rather just give one example from a research study we did of piano performance.

The figure below shows the score and spectrogram of the first 8 measures of the opening of the last movement of L. v. Beethoven�s Piano Sonata nr. 17 Op. 31 no. 2 in d-minor, The Tempest (Example video, not the one used in the experiment). This piece was motion captured, and the figure below also shows plots of the horizontal positions (along keyboard) and absolute velocities of the left and right wrists, elbows, and shoulders of the pianist.

Piano coarticulation
Piano coarticulation

The interesting point here from a chunking and coarticulation perspective, is how the individual notes are merged into larger action chunks. This is particularly visible in the left hand, and can also be refound in the elbows and shoulders. This type of coarticulation is very common in music performance, and is to a large part based on biomechanical constraints. You necessarily have to move your hand in a circular path to be able to play a passage like this.

References

5.13 Introduction to Video Analysis

This week’s methods track will focus on movement analysis using regular video cameras.

Some of the advanced motion capture technologies we have looked at in previous weeks are certainly the best in terms of accuracy, precision and speed. But video analysis is by far the most accessible and easy solution to get started with analysing human motion on a computer.

In the following video we will take a look at how it is possible to use regular video cameras for movement analysis, and we will look at some different visualisation techniques, including motion images and motiongrams.

5.15 Visualising Video

This article presents a set of video-based visualisation techniques developed for the analysis of music-related body motion.

Here in Music Moves we present a number of different types of motion capture technologies. Many of these are excellent and work well for their purposes. Still, however, video recording is most likely the most accessible “motion capture” technology for most people. Video cameras are nowadays easily available everywhere, so anyone can get started right away.

It may be odd to think that it is necessary to create visualisations of a video recording. After all, video is visual to start with. However, watching a running video is not a very efficient way of analysing large sets of video recordings.

Motion images

One of the most common techniques when one works with motion analysis from video files is to start by creating what we call a motion image. The motion image is found by calculating the absolute pixel difference between subsequent frames in a video file, as illustrated in the figure�below. The end result is an image in which only the pixels that have changed between the frames are displayed.

Motion image
Motion image

The quality of the raw motion image depends on the quality of the original video stream. Small changes in lighting, camera motion, compression artefacts, and so on can influence the final image. Such visual interference can be eliminated using a simple low-pass filter to remove pixels below a certain threshold, or a more advanced “noise reduction” filter, as illustrated below. Either tool cleans up the image, leaving only the most salient parts of the activity in the motion.

Filtered motion image
Filtered motion image

The video of the filtered motion image is usually the starting point for further processing and analysis of the video material.

Motion-history images

A motion image represents the motion that takes place between two frames but does not represent a motion sequence that takes place over more frames. To visualise the motion itself over time, then, it is necessary to create a motion-history image�a display that keeps track of the history of what has happened over the course of some number of recent frames. One approach is to simply average over the frames of an entire recording. This produces what could be called an average image or a motion-average image, such as shown below.

Average image
Average image

These images may or may not be interesting to look at, depending on the duration of the recording and the content of the motion. The examples above are made from a short recording that includes only one short passage and a raising of the right hand. The lift is very clearly represented in the motion-average image, whereas the average image mainly indicates that the main part of the body itself stayed more or less in the same place throughout the recording.

For longer recordings, in which there is more activity in larger parts of the image, the average images tend to be more “blurred”�in itself an indication of how the motion is distributed in space.

To clarify the motion-history image, it is possible to combine the average image and the motion-average image, or possibly incorporate one frame (for example, the last frame) into the motion-average image. The latter alternative makes it possible to combine a clear image of the person in the frame with traces of the motion-history, as illustrated below.

motion-history image
motion-history image

Motion history images may be usefl to study, for example, performance techhnique. The figure below shows a visualisation of a percussion study. Here, each image represents an individual stroke on the drum pad, and the image series serves as a compact and efficient visualisation of a total of fourteen different strokes by the percussionist.

Percussion
Percussion

Each of the displays in the figure above represents around fifteen seconds of video material. As such, this figure is a very compact representation of a full recording session.

Motiongrams

The motion-history images above reveal information about the spatial aspects of a motion sequence, but there is no information about the temporal unfolding of the motion. Then a motiongram may be useful, since it displays motion over time. A motiongram is created by averaging over a motion image, as illustrated in the figure below.

Schematic motiongram
Schematic motiongram

This figure shows a schematic overview of the creation of motiongrams, based on a short recording of a piano performance. The horizontal motiongram clearly reveals the lifting of the hands, as well as some swaying in the upper part of the body. The vertical motiongram reveals the motion of the hands along the keyboard, here seen from the front, as in the previous figures.

One example of the ways in which motiongrams can be used to study dance performance can be seen below. This display shows motion-average images and motiongrams of forty seconds of dance improvisation by three different dancers who are moving to the same musical material (approx. forty seconds). A spectrogram of the musical sound is displayed below the motiongrams.

Dancers
Dancers

The motiongrams reveal spatiotemporal information that is not possible to convey using keyframe images, and they facilitate the researcher’s ability to follow the trajectories of the hands and heads of the dancers throughout the sequences.

For example, the first dancer used quite similar motions for the three repeated excerpts in the sequence: a large, slow upwards motion in the arms, followed by a bounce. The third dancer, on the other hand, had more varied motions and covered the whole vertical plane with the arms. Such structural differences and similarities can be identified in the motiongrams, and then studied in more detail in the original video files.

From Music Research to Clinical Practice

We can make a little detour at the end of this article. As researchers working on basic issues, we are often asked about the “usefulnes” of what we do. It is often difficult to answer this question, because our research is not meant to be useful in the first place. But sometimes seemingly “useless” developments can have an impact elsewhere.

The visualisation techniques mentioned above have actually turned out to be very useful in medical research and clinical practice. A group of researchers in Trondheim, Norway, found that the motiongram technique was an excellent way of detecting so-called fidgety motion in infants. This is important when it comes to screening pre-term infants that are in the risk zone for developing cerebral palsy, as shown in this image with a healthy infant (top) and an infant with cerebral palsy (below).

Infants
Infants

References

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Week 6