Understanding Emotion in Raag: an Empirical Study of Listener Responses

UNDERSTANDING EMOTION IN RAAG: AN EMPIRICAL STUDY OF LISTENER RESPONSES Parag Chordia and Alex Rae Georgia Institute of Technology, Department of Music 840 Mc Millan St., Atlanta GA 30332 {ppc,arae3}@gatech.edu ABSTRACT theoretically thousands of scale types; in practice, however, raags conform to a much smaller set of scales, and A survey of emotion in North Indian classical music was many of the most common raags share the same set of undertaken to determine the type and consistency of emo- notes. tional responses to raag. Participants listened to five one- By building phrases as described above, a tonal hier- minute raag excerpts and recorded their emotional responses archy is created. Some tones appear more often in the after each. They were asked to describe the emotions each basic phrases, or are sustained longer. Indian music the- excerpt evoked and then to adjust six different sliders indi- ory has a rich vocabulary for describing the function of cating the degree to which they felt the following: happy, notes in this framework. The most stressed note is called sad, peaceful, tense, romantic, longing. A total of 280 re- the vadi and the second most stressed, traditionally a fifth sponses were received. We find that both free-response or fourth away, is called the samvadi. There are also less and quantitative judgments of emotions are significantly commonly used terms for tones on which phrases begin different for each raag and quite consistent across listen- and end. A typical summary of a raag includes its scale ers. We hypothesized that the primary predictors of emo- type (that), vadi and samvadi. A pitch-class distribution tion in these excerpts would be pitch-class distribution, (PCD), which gives the relative frequency of each scale pitch-class dyad entropy, overall sensory dissonance, and degree, neatly summarizes this information. note density. Multiple regression analysis was used to The performance context of raag music is essentially determine the most important factors, their relative im- monophonic, although vocalists will usually be shadowed portance, and their total predictive value (R2). The fea- by an accompanying melody instrument. The rhythmic tures in combination explained between 11% (peaceful) accompaniment of the tabla is also present in metered sec- and 33% (happy) of response variance. For all models, tions. There is usually an accompanying drone that sounds a subset of the features were significant, with the inter- the tonic and fifth using a harmonically rich timbre. play between “minor” and “major” scale degrees playing an important role. Although the explanatory power of the current models is limited, the results thus far strongly sug- 2. RELATED WORK gest that raags do consistently elicit specific emotions that are linked to musical properties. The responses did not The emotional qualities of raags have been discussed ex- differ significantly for enculturated and non-enculturated tensively in NICM music theory. Traditionally, this mu- listeners, suggesting that musical rather than cultural fac- sic is said to evoke seven basic emotions: sadness, ro- tors are dominant. mance, peace, strength/courage, anger, dispassion, devotion (Bhatkande 1934). In theory, each raag elicits a unique 1. BACKGROUND emotional state (rasa) consisting of one or more of these basic emotions. Raag literally means “that which colors the mind”. It For Western music, a variety of studies have been un- is a melodic abstraction around which almost all North dertaken since the late 19th century to define what emo- Indian classical music (NICM) is organized. A raag is tions music elicits, and to understand the musical factors most easily explained as a collection of melodic gestures that underly them. These studies have followed a basic and a technique for developing them. The gestures are experimental paradigm in which musical excerpts are pre- sequences of notes that are often inflected with various sented to listeners who are then asked to respond by ver- micro-pitch alterations and articulated with an expressive bally describing their emotional states, rating emotions on sense of timing. Longer phrases are built by joining these a quantitative scale, or some other measurement. Musi- melodic atoms together. cal stimuli are chosen so that certain characteristics can NICM uses approximately one hundred raags, of which be systematically varied, such as timbre, tempo and tonal- fifty are common. Despite micro-tonal variation, the tones ity. Correlations between responses and musical structure in any given raag conform to a subset of the twelve chro- are then observed, and are interpreted to account for some matic pitches of a standard just-intoned scale. There are aspect of the listener reactions. 137 A common pitfall in such experiments is the fundamen- CD[ DE[ EFF] GA[ AB[ B tal difficulty of isolating the factor that is being tested. Yaman ••••••• Real musical excerpts rarely vary in just one parameter, Desh ••••••• while artificial stimuli that can be systematically varied Khamaj •••••••• often will not generalize, lacking the “ecological validity” Darbari ••••••• of real music. Most importantly, the difficulty of quanti- Marwa •••••• fying a person’s actual emotional state, either through ob- servation or by eliciting verbal or other responses, makes Table 1. Summary of scale degrees used by raags in such research extremely challenging. Despite this, the database. Notes are listed with C as the tonic. field has produced a body of work that suggests consistent relationships between musical structure and emotional re- http://www. sponse (Balkwill and Thompson 1999). In general, two and the raag excerpts can be heard at paragchordia.com/research broad categories of emotional responses have been found, . Some basic demo- relating to valence (happy-sad) and activity (vigorous-calm). graphic information was collected, specifically age, sex, For example, fast tempo has been shown to correlate con- level of musical training (if any), and familiarity with NICM sistently with positive valence and activity; the same has (if any). For each excerpt, there was both a free response been shown for major (versus minor) tonality. A thorough with the directions to “describe how it makes you feel in overview of the field of emotion and music can be found as much detail as possible,” and a series of six value slid- in Juslin and Sloboda (2001). ers (ranging from zero to one hundred) corresponding to Although the connection between raag and emotion is pre-chosen emotional adjectives: happy, sad, tense, peace- assumed to be systematic by nearly all enculturated lis- ful, romantic, and longing. The adjectives were chosen teners and performers, very little empirical work relating based on preliminary research by the author suggesting to emotion in NICM has been published. In one study, that these might best capture the dominant emotional axes. NICM musicians were asked to play short excerpts that Further, the first four roughly represent the valence and conveyed either joy, sadness, anger, or peace. Listen- activity judgments discussed above. ers not familiar with NICM were asked to identify the Participants were asked to “adjust the slider to indicate predominant emotion. The recognition of intended emo- how well you feel that the word applies to the raag ex- tions was mostly successful except for peace (Balkwill cerpt you just heard.” The order in which each of these and Thompson 1999). sliders appeared was randomized for each raag presented. Each participant was presented with the same set of five raags in a random order. The specific excerpt for each 3. MOTIVATION raag was chosen at random from three possibilities, one played on sarod and two on sitar, both traditional plucked The current work seeks to characterize the emotional re- string instruments. All excerpts were approximately one sponses of listeners to different raags and the extent to minute long, unaccompanied, and from alap, a slower, which listeners report similar experiences; furthermore, if arrhythmic introductory section of a raag performance. responses differ systematically by raag, it seeks to iden- Participants had the option of replaying each segment an tify some of the musical factors that underly these re- unlimited number of times. Without knowing in advance sponses. In NICM, all pitch-related activity is structured how much data we would be able to collect, it was impos- by the choice of raag. Each raag is traditionally asso- sible to determine an appropriate dimensionality for the ciated with several basic emotions. For example, Raag data we sought. Therefore, an attempt was made to strike Yaman is said to evoke peace, happiness, and devotion. a balance, leading to the decision to limit the number of Performers and listeners of NICM often report that the slider-values to six and include a free-response section as essence of raag-based music is the evocation of mood well. This was also the reasoning that determined on the brought about by one or more related emotions, and that one hand the presentation of the same five raags to each different raags reliably elicit different emotional states. In participant, while generalizing slightly by the inclusion of many cases, however, the more traditional descriptions are three audio files for each raag. not accepted, or are thought of as rudimentary. Despite the central role of emotion in raag theory, almost no empirical work has been undertaken to systematically analyze listener response to different raags. 5. SURVEY RESULTS 4. SURVEY DESIGN A total of 280 survey responses were collected. Partici- pants were recruited from online NICM forums, as well as For the purpose of collecting a large number of responses, through the Georgia Institute of Technology music depart- we created an online survey in which participants were ment. 29% of the respondents were female and 71% male, asked to respond to five raag excerpts in terms of “how with a median age of 24. The respondents described their listening to each raag made you feel.” The survey can be familiarity with NICM as “none” (11%), “a little”(24%), found at http://www.paragchordia.com/survey “somewhat”(29%), “very”(32%) and “expert”(4%).

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