Harold Stone Powers (August 5, 1928 – March 15, 2007) was an American musicologist, ethnomusicologist, and music theorist.  
Born in New York City on August 5, 1928, he earned his B.Mus. in piano from Syracuse University in 1950 and an MFA in composition and musicology from Princeton University in 1952. As a Fulbright Fellow, he studied Indian music in Madras for two years before continuing at Princeton where he received a Ph.D. in musicology. His dissertation was on “The Background of the South Indian Raga System.” Powers taught at Harvard University from 1958 to 1960 and at the University of Pennsylvania from 1961 to 1973 before returning to Princeton where he was named the Scheide Professor of Music History in 1995 and in 2001 assumed Emeritus status. Powers returned to India several times to study music there on John D. Rockefeller III and Fulbright Senior fellowships. 
Powers was known for intensive study of both Renaissance music and music theory and several world music traditions (especially Indian music); this allowed him to reevaluate the concept of mode.  He did this in a number of articles, including “Mode” in the New Grove Dictionary of Music and Musicians (1980),  a landmark of scholarship on the subject, "Tonal types and modal categories in Renaissance polyphony" (1981),  "Modal representations in polyphonic offertories" [based mostly on Palestrina's Offertoria cycle] (1982),  "Is mode real?" (1992),  "Anomalous modalities" (1996),  “Language Models and Musical Analysis,”  and “Puccini’s Turandot: The End of the Great Tradition,” 
Powers was the first foreigner to perform at the Tyagaraja Aradhana in Thiruvaiyaru, India. 
The Harold Powers World Travel Fund, administered by the American Musicological Society, was established in 2006 to “encourage and assist Ph.D. candidates, post-docs, and junior faculty in all fields of musical scholarship to travel anywhere in the world to carry out the necessary work for their dissertation or other research. The Fund honors the polymathic scholar and distinguished longtime AMS member whose publications have ranged from music and language to medieval mode to Indian music to Puccini and whose interests are wider still, but always with the communicative aspects of music at their base.” 
In music theory, the term mode or modus is used in a number of distinct senses, depending on context.
Musicology is the scholarly analysis and research-based study of music. Musicology departments traditionally belong to the humanities, although some music research is scientific in focus. Some geographers and anthropologists have an interest in musicology so the social sciences also have an academic interest. A scholar who participates in musical research is a musicologist.
A pentatonic scale is a musical scale with five notes per octave, in contrast to the heptatonic scale, which has seven notes per octave.
A raga or raag is a melodic framework for improvisation in Indian classical music akin to a melodic mode. The rāga is a unique and central feature of the classical Indian music tradition, and as a result has no direct translation to concepts in classical European music. Each rāga is an array of melodic structures with musical motifs, considered in the Indian tradition to have the ability to "colour the mind" and affect the emotions of the audience.
Tonality is the arrangement of pitches and/or chords of a musical work in a hierarchy of perceived relations, stabilities, attractions and directionality. In this hierarchy, the single pitch or triadic chord with the greatest stability is called the tonic. The root of the tonic chord forms the name given to the key, so in the key of C major, the note C is both the tonic of the scale and the root of the tonic chord. Simple folk music songs often start and end with the tonic note. The most common use of the term "is to designate the arrangement of musical phenomena around a referential tonic in European music from about 1600 to about 1910". Contemporary classical music from 1910 to the 2000s may practice or avoid any sort of tonality—but harmony in almost all Western popular music remains tonal. Harmony in jazz includes many but not all tonal characteristics of the European common practice period, usually known as "classical music".
The Aeolian mode is a musical mode or, in modern usage, a diatonic scale also called the natural minor scale. On the white piano keys, it is the scale that starts with A. Its ascending interval form consists of a key note, whole step, half step, whole step, whole step, half step, whole step, whole step. That means that, in A aeolian, you would play A, move up a whole step to B, move up a half step to C, then up a whole step to D, a whole step to E, a half step to F, a whole step to G, and a final whole step to a high A.
The Locrian mode is the seventh mode of the major scale. It is either a musical mode or simply a diatonic scale. On the piano, it is the scale that starts with B and only uses the white keys from there. Its ascending form consists of the key note, then: half step, whole step, whole step, half step, whole step, whole step, whole step.
The American Musicological Society (AMS) is a musicological organization which researches, promotes and produces publications on music. Founded in 1934, the AMS was begun by leading American musicologists of the time, and was crucial in legitimizing musicology as a scholarly discipline.
Melody type or type-melody is a set of melodic formulas, figures, and patterns.
William Oliver Strunk was an American musicologist. Charles Rosen called him one of the most influential American musicologists of the 1930s–1960s. He was known for his anthology Source Readings in Music History (1950) and his work on Byzantine music. He was the son of Elements of Style coauthor William Strunk, Jr. (1869–1946)
Leo Treitler is an American musicologist born in Dortmund, Germany. He is distinguished professor at the Graduate Center of the City University of New York.
"Tu che di gel sei cinta" is a soprano aria from act 3, scene 1, of Puccini's 1926 opera Turandot. It is sung by Liù under torture, prior to her suicide.
Karol Berger is a Polish-American musicologist.
Rose Rosengard Subotnik is a leading American musicologist, generally credited with introducing the writing of Theodor Adorno to English-speaking musicologists in the late 1970s.
Stephen Blum is an American scholar and musician, whose research has primarily been in ethnomusicology. He has lent a multidisciplinary approach to the writing and publication of numerous articles discussing a wide range of musical topics and ideas.
Ruth Katz is an Israeli musicologist, a pioneer of academic musicology in Israel, professor emerita at the Hebrew University of Jerusalem. She has been a corresponding Member of the American Musicological Society since 2011. She was named laureate of the Israel State Prize in 2012.
Jürgen Maehder is a German musicologist and opera director. He discovered Franco Alfano's original version of the finale for the third act of Puccini's Turandot. He has lectured and staged opera internationally.
George Herzog was an American anthropologist, folklorist, musicologist, and ethnomusicologist.
Kii-Ming Lo, born November 4, 1954 in Keelung, is a Taiwanese musicologist.