The influences of progression type and distortion on the perception of terminal power chords

Abstract

The purpose of this study was to investigate the tonal perception and restoration of thirds within power chords with the instruments and sounds idiosyncratic to the Western rock/pop genre. Four separate chord sequences were performed on electric guitar in four versions; as full chord and power chord versions as well as under both clean-tone and distortion effect versions. Undergraduate music majors (N = 50) listened to all 16 chord progressions and rated their perception of the tonality (‘majorness’ or ‘minorness’) in the terminal chord for each sequence, utilizing a 7-point semantic differential scale ranging from minor (1) to major (7) with a neutral indicator located in the middle (4). Participants had completed a mean 3.82 (SD = 0.66) semesters of ear training and 28 indicated they played the guitar. A three-way repeated measures ANOVA revealed significant differences between responses for chord sequences (1–4), as well as a significant interaction between chord sequences, distortion (clean versus distortion), and type of chords in the progression (whole chords versus power chords). Further analysis of data indicated that participants tended to perceive terminal power chords as major, especially when progressions were comprised of power chords and contained distortion.

Keywords

distortion guitar musical perception power chords tonality

The influences of progression type and distortion on the perception of terminal power chords

A considerable amount of extant research indicates that music is a culturally-learned phenomenon (Farnsworth, 1969; Holleran, Jones, & Butler, 1995; Taylor, 1976; Tillmann, Bharucha, & Bigand, 2000; Wassum, 1979). In fact, cultural knowledge has been shown to influence musical expectations (Curtis & Bharucha, 2009; Huron, 2006; Morrison, Demorest, & Stambaugh, 2008; Wong, Roy, & Margulis, 2009) as individuals familiar with Western music appear to develop musical expectations when listening to the melodic, harmonic, and tonal framework of this music genre (Meyer, 1967; Sloboda, 1985), regardless of musical training (Bigand & Poulin-Charronnat, 2006; Cuddy, 1982). Continued examination has revealed that musical expectations are learned at an early age (Boyle & Penticoff, 1989; Costa-Giomi, 1994; Hair, 1973; Wassum, 1979): individuals develop musical expectations for the melodic, harmonic, and tonal content by the age of 7 (Krumhansl & Keil, 1982; Trainor & Trehub, 1994). Furthermore, researchers have postulated that these expectancies for future musical events may result from the unfolding musical pattern that the listener receives (Huron, 2006; Jones, 1981, 1982; Radocy & Boyle, 2003). Thus, based from data cited in the aforementioned studies, it seems axiomatic to state that listeners develop musical expectations based upon previous musical information.

As a listener’s expectations for future musical events arise from the learned associations between musical events (Bharucha & Stoeckig, 1986, 1987; Curtis & Bharucha, 2009), a number of researchers have attempted to examine the formation of expectancies for harmonic and tonal content. Specifically, listeners have shown preferences for individual tones and melodies that utilize strong scale and chord tones within their structure (Gagnon, Hebert, & Peretz, 1995; Krumhansl & Shepard, 1979; Taylor, 1976). Subsequently, individuals tend to rely upon harmonic information when perceiving individual pitches and melodies, and show preference to pitches and melodies that follow harmonic guidelines (Holleran, Jones, & Butler, 1995). Within chord progressions, listeners also tend to prefer specific chords that provide stability to the overall harmonic structure of a chord progression (Krumhansl, Bharucha, & Kessler, 1982), chords that aid in developing a sense of key (Krumhansl & Kessler, 1982; Schmuckler & Boltz, 1994), and chords that are ‘acceptable’ in chord progressions considered standard in the Western musical tradition (Steedman, 1984). Furthermore, when provided with two sequential chords that are harmonically related or unrelated, listeners are able to process related chords at a faster rate than unrelated chords. These results suggest that the first chord can create a harmonic expectation for the second chord (Bharucha & Stoeckig, 1986, 1987).

Because of the expectations that an individual develops while listening to music, several researchers have further examined if listeners can perceive sounds even when they are not physically occurring. Commonly referred to as restoration, this phenomenon involves the process in which auditory signals are perceived due to the information heard before and after the perceived sound (Warren, 1984; Warren, Wrightson, & Puretz, 1988). For example, Sasaki (1980) found that when notes of a familiar melody were deliberately replaced by loud noise, listeners still perceived the tones as sounding; these musical tones were heard as a complete melody with added noise. In a related study, DeWitt and Samuel (1990) also revealed that listeners perceived (a) tones of a melody as sounding when replaced by noise, and (b) pitches within scales and chords as sounding when either removed or replaced by noise. For all participants, the amount of melodic and/or harmonic information provided created a sense of expectation that was directly related to the extent of restoration of sounds perceived by the listener.

While the aforementioned researchers have focused on the musical expectations created by the listeners, the majority of these investigators have examined the classical music genre. However, few researchers have specifically examined aspects of musical expectation within popular music. The emergence of popular music, most notably rock, metal, and pop music, has created a new set of compositional practices (Berger, 1999; Walser, 1993). While several researchers and theorists have criticized the simplistic nature of these compositional structures (Bobbitt, 1976; Shepherd, 1993; Winkler, 1978), other authors have posited that changes to the harmonic and tonal structures within this genre of music have led to the unique sound of rock/pop music (McDonald, 2000; Moore, 1995; Temperley, 2007; Temperley & de Clercq, 2010). Specifically, Temperley (2007) proposed that rock/pop compositions are based upon blues structure and harmony rather than traditional classical structure and harmony. An example of the blues element can be found with the inclusion of the ‘flat seventh’ utilized in rock music, in which the use of the flat seventh interval (instead of the traditional leading tone found in classical music) has led to changes in traditional chord progressions and cadences (Moore, 1995).

Another compositional technique idiosyncratic to the rock/pop genre is the development of the ‘power chord’ (also referred to as a 5th chord). A power chord is a chord without a sounding third, thus producing an open fifth interval. Musicians frequently utilize these chords on the guitar in rock/pop music. Because of the increased timbral complexity of the instrumentation typically found in rock/pop ensembles, many guitarists have simplified their chordal sonorities by removing the third of the major/minor chord (McDonald, 2000). Thus, the power chord is neither major nor minor, in which the absence or flexibility of harmony created by these chord progressions can leave the listener with a certain sense of ambiguity. Additionally, many guitarists utilizing power chords also add distortion to their sound, which can create a ‘thicker’ and more complex overall tone (Walser, 1993).

At present, there is limited research concerning the perception of power chords. One researcher (Pittenger, 2002) asked participants to listen to perfect 5th intervals (i.e., power chords) followed by either a major or minor chord and indicate which of the two completed chords was more similar to the power chord. Results indicated that participants perceived the power chords as more similar to major chords, suggesting that listeners have a propensity to perceive chords without a third as more major than minor. While these findings are important, it would seem that grouping a power chord with a completed chord does not necessarily account for the musical expectations that may be created with the additional musical information a listener receives throughout an entire chord progression. Thus, the perception of power chords within chord progressions may be facilitated by either additional information provided in the music or by restoration of tones on the part of the listener.

Subsequently, Juchniewicz (2009) sought to determine how listeners perceive and restore tones when presented with power chords placed within chord progressions. The researcher created eight chord progressions, consisting of four chords per progression with each progression ending with a power chord. The researcher based these eight progressions upon existing progressions used in a variety of popular Western music rock/pop songs. While all eight progressions were utilized to examine the perception of power chords within chord progressions based on the major and minor harmonic information presented within chord progressions, the researcher was particularly interested in the pairing of two versions of the same progression. Two progressions, one with a sequence of major chords ending with a power chord (F, A♭, E♭, B♭5) and one with the same chord sequence all performed as power chords (F5, A♭5, E♭5, B♭5), were created to examine the perception of a major chord progression versus a power-chord only chord progression (‘5’ indicates ‘power chord’). Conversely, another set of progressions was created in a similar manner to investigate the perception of a minor chord progression versus a power-chord only chord progression (Am, C, Dm, A5 and A5, C5, D5, A5). Participants listened to all eight progressions performed on the piano and rated the tonality (majorness or minorness) of the terminal chord on a semantic differential scale from minor (1) to major (7), with a neutral indicator located in the middle of the scale (4). Results indicated significant differences between each paired set of major and minor chord progressions, thus suggesting that listeners based their perception of the power chords on the previous tonal information presented during the entire chord progression. Additionally, across all eight chord progressions, significant differences were found between the undergraduate and graduate participants: Undergraduate music majors tended to rate most power chords as slightly more major than graduate music majors.

In Juchniewicz (2009), both the pairing of major and minor chord progressions ending with a power chord as well as the same chord sequence performed as all power chords yielded some insight into the influence of previous tonal information on the perception of power chords. However, more than one set of major and minor chord progressions is needed to replicate and substantiate these findings. Additionally, for purposes of generalization, it would be appropriate to replicate the study utilizing music performed on instruments typically germane to popular music where power chords are frequently heard (e.g., the guitar with distortion). Thus, would results be similar if the instruments and sounds idiosyncratic to the Western rock/pop genre were utilized? Therefore, as Juchniewicz (2009) utilized the piano to perform each chord progression, the purpose of the current study was to investigate the tonal perception and restoration of thirds within power chords as performed on guitar under both clean-tone and distortion conditions. Specifically, the following research questions were addressed: (1) Does the use of a chord progression composed of power chords or whole chords effect the perception of a terminal power chord? (2) Does the use of clean-tone or distortion guitar effects influence the perception of power chords? (3) Does the amount of formal ear-training affect how power chords are perceived? (4) Does previous experience playing the guitar influence the tonal perception of power chords?

Method

Participants

Participants (N = 50) were undergraduate music majors from a mid-size southeastern public university. There was no stipulation as to specific majors of the participants, as the researchers recruited students from a variety of undergraduate music degree programs. Of the total participants, 31 of the participants were female and 18 were male. Participants ranged in age from 21 to 29 years (M = 21.24, SD = 2.13) and had successfully completed a mean 3.82 (SD = 0.66) semesters of ear training. The authors did not control for previous years of formal music training. Twenty-eight participants indicated they had previous experience playing the guitar, while 22 participants did not have any prior experience with the guitar.

Materials

The four chord progressions utilized for the present study were selected from progressions used in a previous power chord study created by Juchniewicz (2009). These four chord progressions were based from existing progressions used in a variety of popular Western music rock/pop songs (e.g., ‘Boulevard of Broken Dreams’ by Green Day, ‘Sample in a Jar’ by Phish, ‘Zombie’ by The Cranberries, ‘I Get Around’ by Dragonette, ‘Angie’ by the Rolling Stones, ‘Dani California’ by the Red Hot Chili Peppers). For the purposes of this study, the term ‘power chord’ was operationally defined as a three-pitch chord built as an open fifth interval, without a sounding third, with the root/tonic both as the highest and lowest pitches of the chord (Juchniewicz, 2009; McDonald, 2000). Regardless of key, all chord progressions ended with a power chord as the final chord of the sequence.

In order to examine the tonality of terminal power chords within major and minor chord progressions, power-chord only progressions, and clean-tone and distortion conditions, the four chord progressions (based from popular rock/pop progressions) developed by Juchniewicz (2009) were used to create a total of 16 chord progressions. First, two of the four chord progressions selected contained sequences of major chords ending with a power chord ([progression 1] F, A♭, E♭, B♭5, [progression 2] B♭m, G♭, D♭, A♭5) and two of the four chord progressions contained sequences of minor chords ending with a power chord ([progression 3] Gm, Cm, D, G5, [progression 4] Am, C, Dm, A5). The researchers then created four progressions utilizing the same chord sequences but only performed as power chords ([1] F5, A♭5, E♭5, B♭5; [2] B♭5, G♭5, D♭5, A♭5; [3] G5, C5, D5, G5; [4] A5, C5, D5, A5). Finally, the researchers recorded each of these eight chord progressions twice under both clean-tone and distortion guitar-effect conditions. This resulted in a total of 16 chord progressions. Additionally, to familiarize participants with the listening process and procedure, the researchers created two practice examples containing major and minor chords and utilizing both clean-tone and distortion guitar effects.

The researchers voiced all chords such that major/minor chords were performed as root/fifth/root (octave)/third and power chords as root/fifth/root (octave). The duration of all chords was approximately two seconds. The researchers utilized a single down strum for each chord.

The chord progressions were digitally recorded multiple times by a professional guitarist on a Korg D888 Digital Audio Workstation using a 1968 Fender American Stratocaster with a single-coil neck pick-up through a Line-6 POD Version 2.0 Ultimate Guitar Direct Box on a Line-6 Crunch with no effects. This apparatus was selected to reproduce the clean tone of a 1968 American Stratocaster through a Transistor Amplifier. To create the distortion sound of a 1968 Gibson Les Paul played through a Marshall Stack Amplifier, the professional guitarist played the 1968 Fender American Stratocaster with a Hot Rails double-coil Seymour Duncan bridge pick-up through a Line-6 POD Version 2.0 Ultimate Guitar Direct Box. This was played through a Brit high-gain Marshall JCM-800 Amplifier Modeler. The researchers choose these sounds and instruments as they can be considered germane to Western popular music that frequently uses power chords. From these recordings, the researchers and two independent observers selected the clearest performance for each of the chord progressions. Using Protools HD 7.4 audio software, the researchers layered the progressions so that each chord progression was played twice with three sec separating each performance. The researchers placed a male voice at the beginning of each chord sequence to announce the number of each chord progression. Additionally, to allow time for participants to notate their responses and in an attempt to reduce memory of the previous progression, the researchers placed 10 seconds of 20th-century atonal orchestral music between each chord progression (Juchniewicz, 2008, 2009).

After consulting with several experts in the field of music perception and cognition, the researchers determined that a randomly selected presentation order of the chord progressions (or the utilization of multiple random presentation orders) to control for order effect could produce an unintentional order effect in which certain chord progressions could conceivably influence each other harmonically. Therefore, in order to sequence the presentation order of the progressions such that each chord progression would not influence the subsequent progression harmonically (i.e., avoiding tonic, dominant, and/or subdominant relationships between the end of one chord progression and the beginning of the next) (Juchniewicz, 2009; Krumhansl, Bharucha, & Kessler, 1982) and to avoid successive clean tone or distortion tone conditions, only one presentation order became possible. The researchers then created a master audio CD containing all chord 16 progressions (and two practice examples). The duration of the stimulus CD was approximately 10 minutes.

The researchers created an evaluation form (which included demographic information) for participants to rate the tonality of the final chord for each chord progression (Juchniewicz, 2009). All questions on the evaluation form were based on a 7-point semantic differential scale ranging from minor to major with a neutral indicator located in the middle of the scale. The assessment scale provided indications for the degree of tonality located on the extreme anchors of the scale, from 3 on the left side = strongly minor to 3 on the right side = strongly major, with 0 in the middle = neutral. For purposes of data analyses and clarity, these data were later converted to a 7-point Likert-type scale, with 1 representing strongly minor, 4 representing neutral, and 7 representing strongly major. The evaluation form also contained questions assessing the number of completed semesters of ear training classes, gender, and whether the participants had experience playing the guitar.

Procedure

The Institutional Review Board of the affiliated university where data collection took place approved the study a priori. The principle investigator (PI) recruited potential participants from music classes within the university and tested participants in groups of 10–15. After explaining and obtaining informed consent, the PI distributed the evaluation form and directed participants to complete the demographic information located at the top of the form. The PI then read a short introduction to participants prior to the start of the experiment:

You are participating in a study in which you will be evaluating chords. Sixteen chord progressions, consisting of four chords each, will be played through twice. Upon completion of the second listening, please indicate your perception of the final chord you hear. You will notice the assessment scale is marked from minor to major with varying levels from one to three. These levels are there to allow you to notate the degree of majorness or minorness for your response. For example, if you hear a chord that is strongly major, circle three on the right side for major. If you hear a chord that you perceive to be slightly minor, mark one on the left side for minor. If you hear a chord that you do not believe to be major or minor, mark zero for neutral. Two practice examples are given at the beginning to allow you to become acquainted with the listening process and evaluation. There will be approximately ten sec between performance examples to give you ample time to notate your responses. Please note the evaluation form is two pages with Chord Progressions located on the front and back. Are there any questions? Please do not talk during the experiment.

Upon completion of the experiment, the PI collected evaluation forms. The total duration of the experiment was approximately 13 minutes.

Results

To analyze the perception of tonality in the terminal chord of each progression, the researchers initially utilized a five-way mixed analysis of variance (ANOVA) with between-subjects variables of previous guitar playing experience and semesters of previous ear training and within-subjects variables of chord sequences (1–4), distortion (clean versus distortion), and type of chords in the progression (whole chords only versus power chords only). The researchers specifically choose not to analyze data by major and minor progressions in an attempt to maintain the distinctive and individual nature of each unique chord progression (Juchniewicz, 2009). Results were not significant for between-subjects variables of previous guitar playing experience F(1, 42) = 0.02, p = .60, partial η² = .007 or semesters of ear training F(4, 42) = 0.90, p = .47, partial η² = .079. Additionally, there were no significant interactions in the between-subjects effects or between-subjects effects and any of the other variables (p > .05). Thus, these between-subjects variables were eliminated from final analyses.

Subsequently, the researchers used a three-way repeated measures ANOVA to analyze the primary dependent measure: participants’ perception of tonality in the terminal chord for each progression. Within-subjects variables included chord sequences (1–4); distortion (clean versus distortion); and type of chords in the progression (whole chords only versus power chords only). Concerning main effects, results were not significant for distortion F(1, 149) = 0.41, p = .523, partial η² = .008, or type of chords in the progression F(1, 149) = 2.19, p = .146, partial η² = .043. Main effects were significant for chord sequences, F(3, 147) = 15.58, p < .001, partial η² = .241. Pair-wise comparisons with Bonferroni corrections for multiple comparisons were then conducted to determine where these differences occurred. Significant differences were found between chord progressions 1 and 2 (p < .001), chord progressions 2 and 3 (p < .001), and chord progressions 2 and 4 (p < .001). Overall, participants tended to perceive the terminal power chord in progression 3 as the most major (M = 5.01, SD = 1.87) (see Table 1). Additionally, regardless of distortion or type of chords in the progression, participants tended to perceive all terminal power chords in progressions 1, 2, 3, and 4 as slightly more major than minor (progression 1: M = 4.45, SD = 1.77, progression 2: M = 4.32, SD = 1.77, progression 3: M = 5.01, SD = 1.87, progression 4: M = 4.38, SD = 1.97). Thus, from these results, there was significant variance between chord sequences. Moreover, although not significant, descriptive and graphical data in Table 1 and Figure 1 revealed a slight tendency for participants to perceive terminal power chords as more major during levels of power chords and distortion.

Table 1.

Descriptive statistics

	Overall		Clean				Distortion
	−		Whole chord		Power chord		Whole chord		Power chord
	M	SD	M	SD	M	SD	M	SD	M	SD
Chord sequence 1: F, A♭, E♭, B♭5	4.45	1.77	4.20	1.54	3.66	1.85	4.70	1.94	5.22	1.75
Chord sequence 2: B♭m, G♭, D♭, A♭5	4.32	1.77	3.36	1.74	4.18	1.78	4.76	1.88	4.98	1.67
Chord sequence 3: Gm, Cm, D, G5	5.01	1.87	4.06	2.19	5.26	2.05	4.34	2.26	6.38	0.99
Chord sequence 4: Am, C, Dm, A5	4.38	1.97	3.52	1.79	3.72	1.98	4.80	2.29	5.46	1.81

Notes: Scale: 1 = strongly minor; 4 = neutral; 7 = strongly major

Figure 1.

Three-way interaction between chord sequence (1–4), distortion (clean versus distortion), and type of chords in the progression (whole chord versus power chord).

There was a statistically significant three-way interaction between chord sequences, distortion, and type of chords in the progression, F(3, 147) = 32.52, p < .001, partial η² = .396. There was a significant two-way interaction between chord sequences and distortion (F[3, 147] = 8.90, p < .001, partial η² = .154). Interactions were not significant between distortion and type of chords in the progression (F[1, 49] = 2.41, p = .127, partial η² = .047) and chord sequences and type of chords in the progression (F[3,147] = 1.46, p = .226, partial η² = .029). Interactions between variables are depicted graphically in Figure 1.

Discussion

The purpose of this study was to investigate the tonal perception and restoration of thirds in power chords with the instruments and sounds idiosyncratic to the Western rock/pop genre.

Results indicated that the overall mean, comprised of listeners’ perception of the terminal power chord during chord progressions presented under clean-tone and distortion effect conditions as well as whole-chords only and power-chords only conditions, was the highest for chord progression 3 (Gm, Cm, D, G5), and thus was perceived as the most major terminal power chord. Considering this progression contained sequences of minor chords ending with a power chord this result was not expected (Juchniewicz, 2009). Additionally, it is intriguing that the terminal power chords in progressions 1 (F, A♭, E♭, B♭5) and 2 (B♭m, G♭, D♭, A♭5), while still perceived as slightly major, received lower overall mean ratings than the terminal power chord in progression 3. This finding is of particular interest, as progressions 1 and 2 were constructed to contain sequences of major chords ending with a power chord, but participants perceived the terminal power chord in progression 3 as more major than the terminal power chords in progressions 1 and 2. Further, as chord progression 4 (Am, C, Dm, A5) was constructed as a minor progression, and in a similar fashion as progression 3 (during whole chord conditions) actually contained the terminal power chord as a previously sounding minor chord, the fact that the overall means for both progressions 3 and 4 were perceived as slightly major is certainly interesting and merits future investigation. Therefore, while these results contradict previous findings concerning perceptions of terminal power chords within both major and minor chord progressions (Juchniewicz, 2009), these results appear to highlight significant variance between chord sequences. Thus, it seems that each chord sequence had unique properties that, in turn, affected perception of the terminal power chord.

Further examination of data indicated that participants tended to perceive terminal chords as more major when progressions utilized power chords and distortion. Furthermore, participants tended to not perceive terminal power chords as minor: Only four of the 16 means found for the four different listening conditions displayed in Figure 1 were below the neutral indicator of the scale. These results are congruent with existing research that has demonstrated that listeners tend to perceive open-fifth intervals as major (Pittenger, 2002). However, these findings conflict with Juchniewicz (2009), who found that while undergraduate listeners did perceive power chords as slightly more major than graduate listeners, the major or minor information presented in the chord progression influenced the direction in which these listeners perceived the terminal power chord. Thus, in Juchniewicz (2009), participants tended to perceive the terminal power chord as minor when the progression was minor. This was not the case in the current study: Results indicated that, regardless of major or minor harmonic information presented in the progression, participants tended to rate the terminal power chords utilizing power chords in the progression and distortion as more major. Perhaps the ‘musical environment’ (in this case, the chord sequence before the terminal power chord and/or the distortion) creates anticipation that a chord will be major and previously heard power chords within the progression and distortion heighten this expectancy. Other researchers have found tendencies for participants to imagine chords as major (Huron, 2006) and classify melodies as major (Halpern, Martin, & Reed, 2008). Future research is warranted to determine if the addition of distortion and power chords intensifies the tendency toward perceiving melodies and/or chords as major.

Between-subjects effects of previous guitar-playing experience or semesters of ear training did not affect perception of tonality. This finding is consistent with existing research suggesting that tonality is culturally learned (Farnsworth, 1969; Holleran, Jones, & Butler, 1995; Huron, 2006; Meyer, 1967; Sloboda, 1985; Taylor, 1976; Tillmann, Bharucha, & Bigand, 2000; Wassum, 1979). However, the researchers only utilized undergraduate music majors – who were trained as Western/classical musicians – as participants. Furthermore, as most university ear training classes do not utilize power chords, guitars, or distortion, it seems appropriate that ear training experience did not affect data. Although previous research has consistently indicated that musical training does not affect perception of tonality (Bigand & Poulin-Charronnat, 2006; Cuddy, 1982), results may have been different if vernacular musicians were compared with music majors (Woody & Lehmann, 2010) or if musicians from other non-Western musical cultures served as participants. These questions could certainly represent future areas for systematic inquiry.

Another question concerned the idiosyncratic sounds of Western popular music: Are chord progressions and power chords perceived differently when played on guitar as opposed to piano? As Juchniewicz (2009) recorded each chord progression on piano, the use of the guitar for the present study may account for differences in the perception of the terminal power chords as major. Furthermore, previous researchers have not utilized distortion. Does the use of distortion with a guitar provide additional musical information to the listener, and therefore, influence the perception of power chords? McDonald (2000) asserts that the use of distortion creates a thick tone by increasing the amount of audible upper partials. Within the harmonic, or overtone series, the first six partials outline a major chord, with the 5th partial producing the sound of a major third from the fundamental tone. Therefore, if the use of distortion increases the aural perception of these partials, most notably the sounding major third in the 5th partial, participants may have been influenced by these overtones and perceived these neutral chords as major. This extra musical information may account for why participants perceived the power chords as more major when performed with distortion as opposed to the clean-tone condition. Future researchers may wish to include a Fourier analysis of the sustained portion of the terminal chord in an attempt to examine the overtone series produced by the power chords.

It is also possible that differences found between chord sequences were related to the individual nature of each unique chord progression. As there are infinitely many different chord progressions, it may be that each individual progression has its own particular sound and tonality. Future research is warranted to better understand how musical elements such as power chords, progressions, timbre and distortion can affect perception of tonality in power chords. Additionally, studying the interaction – or lack thereof – of these elements may provide additional insight into musical preference, perception, and cognition. During future research trials, researchers could also investigate different strum patterns on the guitar: In the current study, the researchers only utilized down-strums in an attempt to control for this potentially confounding variable. However, it may be that more complicated strum patterns (i.e., utilizing both down and up strums in syncopated rhythms) can further influence perception of tonality. These issues certainly represent future areas for systematic inquiry.

One potential limitation of this investigation includes the absence of data indicating participants’ average years of formal training. While the researchers provided mean age and other demographic information concerning participants’ musical background, the unavailability of data concerning participants’ years of formal training makes it difficult to report specific musical expertise/sophistication. While this is certainly a limitation of the current study, issues concerning formal music training are typically complicated to define and control. There is also the possibility that order, learning, and practice effects may have influenced data. Originally, the researchers debated utilizing multiple randomized orders or a Latin Square Design in an attempt to control for these kinds of effects. However, after consulting with external experts in music perception, cognition, theory, and research design, the researchers decided to not use randomization in an attempt to avoid having similar progressions or influential chords played sequentially (Juchniewicz, 2009; Krumhansl, Bharucha, & Kessler, 1982). The researchers also utilized 10-sec of 20th-century atonal orchestral music between the chord progressions in an attempt to reduce/eliminate memory of the previous progression (Juchniewicz, 2008, 2009). Future researchers might wish to include additional steps to help control for possible order effects when investigating the perception of a terminal power chord after listening to repeated recordings of similar progressions. Finally, while a more theoretical analysis of the power chords, including Fourier analysis, keyfinding algorithms (Krumhansl, 2001; Temperley, 1999), and spectrograms may have produced more definitive conclusions as to what was physically sounding within the power chords, the primary focus of this investigation was to ascertain undergraduate participants’ initial perceptions of power chords within varying chord progressions and guitar effects conditions. Subsequent research examining power chords from a theoretical, perceptual, and acoustical basis is certainly warranted to obtain a more holistic sense of how people perceive power chords.

The purpose of this study was to investigate the tonal perception and restoration of thirds within power chords with instruments and sounds idiosyncratic to the Western rock/pop genre. Since previous researchers had not utilized guitar or distortion, the current study was unique in that it incorporated guitar, power chords, and distortion – all musical elements germane to Western popular music. Future research in this area could involve the use of power chords in other modes (e.g., lyidan, mixolydian, dorian, etc.), different types of strum patterns, or other guitar tunings (e.g., dropped D or open chord). Additionally, researchers could investigate perception of tonality in other types of guitar effects frequently associated with Western popular music such as flangers, wa-wa pedals, delay, and other digital enhancements. Although the current study utilized power chords composed of three notes (root, fifth, and root/octave), guitarists often play power chords using only two notes (root and fifth). Researchers could investigate if the addition of the highest sounding root/octave influences perception. Future research is warranted to better understand how listeners, both musically trained and not-trained, perceive sounds idiosyncratic to the Western rock/pop genre.

Footnotes

Author biographies

Jay Juchniewicz is assistant professor of music education at East Carolina University. His research interests are in perception and cognition and music teacher education.

Michael J. Silverman is director of music therapy at the University of Minnesota. His research interests are in psychiatric music therapy and utilizing music to facilitate memory.

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