In music, a trio is a method of instrumentation or vocalization by three different sounds or voices to make a melodious music or song. In general, "trio" voices; the term is used to describe a composition for such a group. The most common types of such compositions are the "piano trio"—piano and cello—and the "string trio"—violin and cello. In vocal music, the term "terzet" is sometimes preferred to "trio". From the 17th century onward the word "trio" is used to describe a contrasting second or middle dance appearing between two statements of a principal dance, such as a minuet or bourée; this second dance was called a "trio" from the 17th-century practice of scoring it for three instruments, for example two oboes and bassoon. Examples continued to be referred to as trios when they involved a larger number of parts. In the 18th century, the term "trio" was used to describe any instrumental composition for three unaccompanied musical strands, regardless of the number of instruments involved. Trios for a single keyboard instrument are found in the music of Johann Sebastian Bach, for example his organ trios, BWV 525–30, three-part inventions, or Sinfonias, BWV 787–801.
"Trio" occurs in the name for the musical form trio sonata, popular in the 17th and early 18th centuries. A trio sonata is written for two solo melodic instruments and basso continuo, making three parts in all, hence the name trio sonata. However, because the basso continuo is made up of at least two instruments, performances of trio sonatas involve at least four musicians. In rock music, bands most have four to five members, but there are many three-person bands. Notable examples of trios following this pattern include The Police, Motörhead and Nirvana. However, there are other variations, for example Emerson, Lake & Palmer, where the guitar is replaced by a keyboard. Jimi Hendrix, although remembered as a soloist performed as part of a trio; the Bee Gees were a popular trio during the Disco music era. A trio may rely on a combination of instrumentation and vocal harmonization. Crosby, Stills, & Nash began; some trios rely on the singing skills of the performers working in front of pre-recorded instrumental tracks.
These include groups like Destiny's Child and TLC. In rap music, a trio may be composed of three performers who alternate vocal parts, as with The Beastie Boys, The Lonely Island, Foreign Beggars, or may be two vocalists along with a DJ who provides the instrumentation through sampling and turntablism, as with Salt-N-Pepa, composed of two vocalists and DJ Spinderella. Common forms of trio include: Brass trio Clarinet-cello-piano trio Clarinet-viola-piano trio Clarinet-violin-piano trio Flute and harp Harmonica trio Horn trio Jazz trio Organ trio Piano trio Power trio String trio Trio sonata Category:Musical trios McClymonds, Marita P. Elisabeth Cook, Julian Budden. 1992. "Trio ". The New Grove Dictionary of Opera, 4 vols. Edited by Stanley Sadie. London: Macmillan Press Limited. ISBN 9780935859928. Randel, Don Michael. 2003. The Harvard Dictionary of Music, fourth edition. Cambridge: Belknap Press of Harvard University Press. ISBN 978-0674011632. Schwandt, Erich. 2001. "Trio". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell.
London: Macmillan Publishers
The public domain consists of all the creative works to which no exclusive intellectual property rights apply. Those rights may have been forfeited, expressly waived, or may be inapplicable; the works of William Shakespeare and Beethoven, most early silent films, are in the public domain either by virtue of their having been created before copyright existed, or by their copyright term having expired. Some works are not covered by copyright, are therefore in the public domain—among them the formulae of Newtonian physics, cooking recipes, all computer software created prior to 1974. Other works are dedicated by their authors to the public domain; the term public domain is not applied to situations where the creator of a work retains residual rights, in which case use of the work is referred to as "under license" or "with permission". As rights vary by country and jurisdiction, a work may be subject to rights in one country and be in the public domain in another; some rights depend on registrations on a country-by-country basis, the absence of registration in a particular country, if required, gives rise to public-domain status for a work in that country.
The term public domain may be interchangeably used with other imprecise or undefined terms such as the "public sphere" or "commons", including concepts such as the "commons of the mind", the "intellectual commons", the "information commons". Although the term "domain" did not come into use until the mid-18th century, the concept "can be traced back to the ancient Roman Law, as a preset system included in the property right system." The Romans had a large proprietary rights system where they defined "many things that cannot be owned" as res nullius, res communes, res publicae and res universitatis. The term res nullius was defined as things not yet appropriated; the term res communes was defined as "things that could be enjoyed by mankind, such as air and ocean." The term res publicae referred to things that were shared by all citizens, the term res universitatis meant things that were owned by the municipalities of Rome. When looking at it from a historical perspective, one could say the construction of the idea of "public domain" sprouted from the concepts of res communes, res publicae, res universitatis in early Roman law.
When the first early copyright law was first established in Britain with the Statute of Anne in 1710, public domain did not appear. However, similar concepts were developed by French jurists in the 18th century. Instead of "public domain", they used terms such as publici juris or propriété publique to describe works that were not covered by copyright law; the phrase "fall in the public domain" can be traced to mid-19th century France to describe the end of copyright term. The French poet Alfred de Vigny equated the expiration of copyright with a work falling "into the sink hole of public domain" and if the public domain receives any attention from intellectual property lawyers it is still treated as little more than that, left when intellectual property rights, such as copyright and trademarks, expire or are abandoned. In this historical context Paul Torremans describes copyright as a, "little coral reef of private right jutting up from the ocean of the public domain." Copyright law differs by country, the American legal scholar Pamela Samuelson has described the public domain as being "different sizes at different times in different countries".
Definitions of the boundaries of the public domain in relation to copyright, or intellectual property more regard the public domain as a negative space. According to James Boyle this definition underlines common usage of the term public domain and equates the public domain to public property and works in copyright to private property. However, the usage of the term public domain can be more granular, including for example uses of works in copyright permitted by copyright exceptions; such a definition regards work in copyright as private property subject to fair-use rights and limitation on ownership. A conceptual definition comes from Lange, who focused on what the public domain should be: "it should be a place of sanctuary for individual creative expression, a sanctuary conferring affirmative protection against the forces of private appropriation that threatened such expression". Patterson and Lindberg described the public domain not as a "territory", but rather as a concept: "here are certain materials – the air we breathe, rain, life, thoughts, ideas, numbers – not subject to private ownership.
The materials that compose our cultural heritage must be free for all living to use no less than matter necessary for biological survival." The term public domain may be interchangeably used with other imprecise or undefined terms such as the "public sphere" or "commons", including concepts such as the "commons of the mind", the "intellectual commons", the "information commons". A public-domain book is a book with no copyright, a book, created without a license, or a book where its copyrights expired or have been forfeited. In most countries the term of protection of copyright lasts until January first, 70 years after the death of the latest living author; the longest copyright term is in Mexico, which has life plus 100 years for all deaths since July 1928. A notable exception is the United States, where every book and tale published prior to 1924 is in the public domain.
In music, polyphony is one type of musical texture, where a texture is speaking, the way that melodic and harmonic aspects of a musical composition are combined to shape the overall sound and quality of the work. In particular, polyphony consists of two or more simultaneous lines of independent melody, as opposed to a musical texture with just one voice, monophony, or a texture with one dominant melodic voice accompanied by chords, called homophony. Within the context of the Western musical tradition, the term polyphony is used to refer to music of the late Middle Ages and Renaissance. Baroque forms such as fugue, which might be called polyphonic, are described instead as contrapuntal; as opposed to the species terminology of counterpoint, polyphony was either "pitch-against-pitch" / "point-against-point" or "sustained-pitch" in one part with melismas of varying lengths in another. In all cases the conception was what Margaret Bent calls "dyadic counterpoint", with each part being written against one other part, with all parts modified if needed in the end.
This point-against-point conception is opposed to "successive composition", where voices were written in an order with each new voice fitting into the whole so far constructed, assumed. The term polyphony is sometimes used more broadly, to describe any musical texture, not monophonic; such a perspective considers homophony as a sub-type of polyphony. Traditional polyphony has a wide, if uneven, distribution among the peoples of the world. Most polyphonic regions of the world are in sub-Saharan Africa and Oceania, it is believed that the origins of polyphony in traditional music vastly predate the emergence of polyphony in European professional music. There are two contradictory approaches to the problem of the origins of vocal polyphony: the Cultural Model, the Evolutionary Model. According to the Cultural Model, the origins of polyphony are connected to the development of human musical culture. According to the Evolutionary Model, the origins of polyphonic singing are much deeper, are connected to the earlier stages of human evolution.
Although the exact origins of polyphony in the Western church traditions are unknown, the treatises Musica enchiriadis and Scolica enchiriadis, both dating from c. 900, are considered the oldest extant written examples of polyphony. These treatises provided examples of two-voice note-against-note embellishments of chants using parallel octaves and fourths. Rather than being fixed works, they indicated ways of improvising polyphony during performance; the Winchester Troper, from c. 1000, is the oldest extant example of notated polyphony for chant performance, although the notation does not indicate precise pitch levels or durations. European polyphony rose out of melismatic organum, the earliest harmonization of the chant. Twelfth-century composers, such as Léonin and Pérotin developed the organum, introduced centuries earlier, added a third and fourth voice to the now homophonic chant. In the thirteenth century, the chant-based tenor was becoming altered and hidden beneath secular tunes, obscuring the sacred texts as composers continued to play with this new invention called polyphony.
The lyrics of love poems might be sung above sacred texts in the form of a trope, or the sacred text might be placed within a familiar secular melody. The oldest surviving piece of six-part music is the English rota; these musical innovations appeared in a greater context of societal change. After the first millennium, European monks decided to start translating the works of Greek philosophers into the vernacular. Western Europeans were aware of Plato and Hippocrates during the Middle Ages; however they had lost touch with the content of their surviving works because the use of Greek as a living language was restricted to the lands of the Eastern Roman Empire. Once these ancient works started being translated thus becoming accessible, the philosophies had a great impact on the mind of Western Europe; this sparked a number of innovations in medicine, science and music. European polyphony rose prior to, during the period of the Western Schism. Avignon, the seat of the antipopes, was a vigorous center of secular music-making, much of which influenced sacred polyphony.
It was not polyphony that offended the medieval ears, but the notion of secular music merging with the sacred and making its way into the papal court. It gave church music more of a jocular performance quality removing the solemn worship they were accustomed to; the use of and attitude toward polyphony varied in the Avignon court from the beginning to the end of its religious importance in the fourteenth century. Harmony was not only considered frivolous and lascivious, but an obstruction to the audibility of the words. Instruments, as well as certain modes, were forbidden in the church because of their association with secular music and pagan rites. Dissonant clashes of notes give a creepy feeling, labeled as evil, fueling their argument against polyphony as being the devil’s music. After banishing polyphony from the Liturgy in 1322, Pope John XXII spoke in his 1324 bull Docta Sanctorum Patrum warning against the unbecoming elements of this musical innovation. Pope Clement VI, indulged in it.
The oldest extant polyphonic setting o
A troubadour was a composer and performer of Old Occitan lyric poetry during the High Middle Ages. Since the word troubadour is etymologically masculine, a female troubadour is called a trobairitz; the troubadour school or tradition began in the late 11th century in Occitania, but it subsequently spread to Italy and Spain. Under the influence of the troubadours, related movements sprang up throughout Europe: the Minnesang in Germany, trovadorismo in Galicia and Portugal, that of the trouvères in northern France. Dante Alighieri in his De vulgari eloquentia defined the troubadour lyric as fictio rethorica musicaque poita: rhetorical and poetical fiction. After the "classical" period around the turn of the 13th century and a mid-century resurgence, the art of the troubadours declined in the 14th century and around the time of the Black Death it died out; the texts of troubadour songs deal with themes of chivalry and courtly love. Most were metaphysical and formulaic. Many were humorous or vulgar satires.
Works can be grouped into three styles: the trobar leu, trobar ric, trobar clus. There were many genres, the most popular being the canso, but sirventes and tensos were popular in the post-classical period; the oldest mention of the word troubadour as trobadors is found in a 12th-century Occitan text by Cercamon. The English word troubadour is an exact rendition from a French word first recorded in 1575 in an historical context to mean "langue d'oc poet at the court in the 12th and 13th century"; the French word is borrowed itself from the Occitan word trobador. It is the oblique case of the nominative trobaire “composer", related to trobar “to compose, to discuss, to invent" It may come from the hypothetical Late Latin *tropāre “to compose, to invent a poem" by regular phonetic change; this recreated form is deduced from the Latin root tropus, meaning a trope and the various meanings of the Old Occitan related words. In turn, the Latin word derives from Greek τρόπος, meaning "turn, manner". B Intervocal Latin shifted to in Occitan.
The Latin suffix -ātor, -atōris explains the Occitan suffix, according to its declension and accentuation: Gallo-Romance *TROPĀTOR > Occitan trobaire and *TROPATŌRE > Occitan trobador « troubadour ». There is an alternative theory to explain the meaning of trobar as “to compose, to discuss, to invent", it has the support of some historians, specialists of literature and musicologists to justify of the troubadours' origins in Arabic Andalusian musical practices. According to them, the Arabic word ṭaraba “song" could be the etymon of the verb trobar. Another Arabic root had been proposed before: Ḍ-R-B “strike", by extension “play a musical instrument", they entertain the possibility that the nearly homophonous Ḍ-R-B root may have contributed to the sense of the newly coined Romance verb trobar. Some proponents of this theory argue, only on cultural grounds, that both etymologies may well be correct, that there may have been a conscious poetic exploitation of the phonological coincidence between trobar and the triliteral Arabic root Ṭ-R-B when Sufi Islamic musical forms with a love theme first spread from Al-Andalus to southern France.
It has been pointed out that the concepts of "finding", "music", "love", "ardour" — the precise semantic field attached to the word troubadour — are allied in Arabic under a single root W-J-D that plays a major role in Sufic discussions of music, that the word troubadour may in part reflect this. The linguistic facts do not support a hypothetical theory: the word trover is mentioned in French as soon as the 10th century before trobar in Occitan and the word trovere > trouvère appears simultaneously in French as trobador in Occitan. In archaic and classical troubadour poetry, the word is only used in a mocking sense, having more or less the meaning of "somebody who makes things up". Cercamon writes: Ist trobador, entre ver e mentir, Afollon drutz e molhers et espos, E van dizen qu'Amors vay en biays. Peire d'Alvernha begins his famous mockery of contemporary authors cantarai d'aquest trobadors, after which he proceeds to explain why none of them is worth anything; when referring to themselves troubadours invariably use the word "chantaire".
The early study of the troubadours focused intensely on their origins. No academic consensus was achieved in the area. Today, one can distinguish at least eleven competing theories: Arabic The sixteenth century Italian historian Giammaria Barbieri was the first to suggest Arabian influences on the music of the troubadours. Scholars like J. B. Trend have asserted that the poetry of troubadours is connected to Arabic poetry written in Spain, while others have attempted to find direct evidence of this influence. In examining the works of William IX of Aquitaine, Évariste Lévi-Provençal and other scholars found three lines that they believed were in some form of Arabic, indicating a potential Andalusian origin for his works; the scholar
Sheet music is a handwritten or printed form of music notation that uses modern musical symbols to indicate the pitches, rhythms or chords of a song or instrumental musical piece. Like its analogs – printed books or pamphlets in English, Arabic or other languages – the medium of sheet music is paper, although the access to musical notation since the 1980s has included the presentation of musical notation on computer screens and the development of scorewriter computer programs that can notate a song or piece electronically, and, in some cases, "play back" the notated music using a synthesizer or virtual instruments. Use of the term "sheet" is intended to differentiate written or printed forms of music from sound recordings, radio or TV broadcasts or recorded live performances, which may capture film or video footage of the performance as well as the audio component. In everyday use, "sheet music" can refer to the print publication of commercial sheet music in conjunction with the release of a new film, TV show, record album, or other special or popular event which involves music.
The first printed sheet music made with a printing press was made in 1473. Sheet music is the basic form in which Western classical music is notated so that it can be learned and performed by solo singers or instrumentalists or musical ensembles. Many forms of traditional and popular Western music are learned by singers and musicians "by ear", rather than by using sheet music; the term score is a common alternative term for sheet music, there are several types of scores, as discussed below. The term score can refer to theatre music, orchestral music or songs written for a play, opera or ballet, or to music or songs written for a television programme or film. Sheet music from the 20th and 21st century indicates the title of the song or composition on a title page or cover, or on the top of the first page, if there is no title page or cover. If the song or piece is from a movie, Broadway musical, or opera, the title of the main work from which the song/piece is taken may be indicated. If the songwriter or composer is known, her or his name is indicated along with the title.
The sheet music may indicate the name of the lyric-writer, if the lyrics are by a person other than one of the songwriters or composers. It may the name of the arranger, if the song or piece has been arranged for the publication. No songwriter or composer name may be indicated for old folk music, traditional songs in genres such as blues and bluegrass, old traditional hymns and spirituals, because for this music, the authors are unknown; the type of musical notation varies a great deal by style of music. In most classical music, the melody and accompaniment parts are notated on the lines of a staff using round note heads. In classical sheet music, the staff contains: a clef, such as bass clef or treble clef a key signature indicating the key—for instance, a key signature with three sharps is used for the key of either A major or F♯ minor a time signature, which has two numbers aligned vertically with the bottom number indicating the note value that represents one beat and the top number indicating how many beats are in a bar—for instance, a time signature of 24 indicates that there are two quarter notes per bar.
Most songs and pieces from the Classical period onward indicate the piece's tempo using an expression—often in Italian—such as Allegro or Grave as well as its dynamics. The lyrics, if present, are written near the melody notes. However, music from the Baroque era or earlier eras may have neither a tempo marking nor a dynamic indication; the singers and musicians of that era were expected to know what tempo and loudness to play or sing a given song or piece due to their musical experience and knowledge. In the contemporary classical music era, in some cases before, composers used their native language for tempo indications, rather than Italian or added metronome markings; these conventions of classical music notation, in particular the use of English tempo instructions, are used for sheet music versions of 20th and 21st century popular music songs. Popular music songs indicate both the tempo and genre: "slow blues" or "uptempo rock". Pop songs contain chord names above the staff using letter names, so that an acoustic guitarist or pianist can improvise a chordal accompaniment.
In other styles of music, different musical notation methods may be used. In jazz, while most professional performers can read "classical"-style notation, many jazz tunes are notated using chord charts, which indicate the chord progression of a song and its form. Members of a jazz rhythm section use the chord chart to guide their improvised accompaniment parts, while the "lead instruments" in a jazz group, such as a saxophone player or trumpeter, use the chord changes to guide their solo improvisation. Like popular music songs, jazz tunes indicate both the tempo and genre: "slow blues" or "fast bop". Professional country music session musicians use music notated in the Nashville Number System, which indicates th
A novelty song is a comical or nonsensical song, performed principally for its comical effect. Humorous songs, or those containing humorous elements, are not novelty songs; the term arose in Tin Pan Alley to describe one of the major divisions of popular music. Novelty songs achieved great popularity during the 1930s, they had a resurgence of interest in the 1960s. Novelty songs are a parody or humor song, may apply to a current event such as a holiday or a fad such as a dance or TV programme. Many use unusual lyrics, sounds, or instrumentation, may not be musical. For example, the 1966 novelty song "They're Coming to Take Me Away, Ha-Haaa!" has little music and is set to a rhythm tapped out on a snare drum and tambourine. A book on achieving an attention-grabbing novelty single is The Manual, written by The KLF, it is based on their achievement of a UK number-one single with "Doctorin' the Tardis", a 1988 dance remix mashup of the Doctor Who theme music released under the name of'The Timelords.'
It argued that achieving a number one single could be achieved less by musical talent than through market research and gimmicks matched to an underlying danceable groove. Novelty songs were a major staple of Tin Pan Alley from its start in the late 19th century, they continued to proliferate in the early years of the 20th century, some rising to be among the biggest hits of the era. Varieties included songs with an unusual gimmick, such as the stuttering in "K-K-K-Katy" or the playful boop-boop-a-doops of "I Wanna Be Loved By You", which made a star out of Helen Kane and inspired the creation of Betty Boop. We Have No Bananas"; these songs were perfect for the medium of Vaudeville, performers such as Eddie Cantor and Sophie Tucker became well-known for such songs. Zez Confrey's 1920s instrumental compositions, which involved gimmicky approaches or maniacally rapid tempos, were popular enough to start a fad of novelty piano pieces that lasted through the decade; the fad was brought about by the increasing availability of audio recordings by way of the player piano and the phonograph.
A 1940s novelty song was Spike Jones' 1942 "Der Fuehrer's Face", which included raspberries in its chorus. Tex Williams's "Smoke! Smoke! Smoke!" Topped the Billboard best-sellers chart for six weeks and the country music chart for 16 weeks in 1947 and 1948. Hank Williams, Sr.'s "Move It On Over," his first hit song, has some humor and novelty elements, but contemporaries disputed this and noted that many men had been faced with eviction under similar circumstances. The 1953 #1 single " That Doggie in the Window?" became notable both for its extensive airplay and the backlash from listeners who found it annoying. Satirists such as Stan Freberg and Tom Lehrer used novelty songs to poke fun at contemporary pop culture in the 1950s and early 1960s. In 1951, Frank Sinatra was paired in a CBS television special with TV personality Dagmar. Mitch Miller at Columbia Records became intrigued with the pairing and compelled songwriter Dick Manning to compose a song for the two of them; the result was "Mama Will Bark", a novelty song performed by Sinatra with interspersed spoken statements by Dagmar, saying things like "mama will bark", "mama will spank", "papa will spank".
The recording includes the sound of a dog yowling. It is regarded by both music scholars and Sinatra enthusiasts to be the worst song he recorded. Sinatra would in fact record a few others before he left Columbia and joined Capitol Records in 1952. Dickie Goodman faced a lawsuit for his 1956 novelty song "The Flying Saucer", which sampled snippets of contemporary hits without permission and arranged them to resemble interviews with an alien landing on Earth. Goodman released more hit singles in the same vein for the next two decades including his gold record RIAA certified hit with Mr. Jaws in 1975 which charted #1 in Cash Box and Record World and was based on the movie Jaws. Among the more far out songs of this genre was the two released in 1956 by Nervous Norvus, "Transfusion" and "Ape Call"; the Coasters had novelty songs such as "Charlie Brown" and "Yakety Yak". "Yakety Yak" became a #1 single on July 21, 1958, is the only novelty song included in the Songs of the Century. "Lucky Ladybug" by Billy and Lillie was popular in December 1958.
Lonnie Donegan's 1959 cover of the 1924 novelty song "Does Your Chewing Gum Lose Its Flavour" was a transatlantic hit, reaching #5 on the Billboard charts two years after its release. Three songs using a sped-up recording technique became #1 hits in the United States in 1958-59: David Seville's "Witch Doctor" and Ragtime Cowboy Joe, Sheb Wooley's "The Purple People Eater", Seville's "The Chipmunk Song", which used a speeded-up voice technique to sim
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds. In ornithology and birding, songs are distinguished by function from calls; the distinction between songs and calls is based upon complexity and context. Songs are longer and more complex and are associated with courtship and mating, while calls tend to serve such functions as alarms or keeping members of a flock in contact. Other authorities such as Howell and Webb make the distinction based on function, so that short vocalizations, such as those of pigeons, non-vocal sounds, such as the drumming of woodpeckers and the "winnowing" of snipes' wings in display flight, are considered songs. Still others require song to have syllabic diversity and temporal regularity akin to the repetitive and transformative patterns that define music, it is agreed upon in birding and ornithology which sounds are songs and which are calls, a good field guide will differentiate between the two. Bird song is best developed in the order Passeriformes.
Some groups are nearly voiceless, producing only percussive and rhythmic sounds, such as the storks, which clatter their bills. In some manakins, the males have evolved several mechanisms for mechanical sound production, including mechanisms for stridulation not unlike those found in some insects. Song is delivered from prominent perches, although some species may sing when flying; the production of sounds by mechanical means as opposed to the use of the syrinx has been termed variously instrumental music by Charles Darwin, mechanical sounds and more sonation. The term sonate has been defined as the act of producing non-vocal sounds that are intentionally modulated communicative signals, produced using non-syringeal structures such as the bill, tail and body feathers. In extratropical Eurasia and the Americas all song is produced by male birds; these differences have been known for a long time and are attributed to the much less regular and seasonal climate of Australian and African arid zones requiring that birds breed at any time when conditions are favourable, although they cannot breed in many years because food supply never increases above a minimal level.
With aseasonal irregular breeding, both sexes must be brought into breeding condition and vocalisation duetting, serves this purpose. The high frequency of female vocalisations in the tropics and Southern Africa may relate to low mortality rates producing much stronger pair-bonding and territoriality; the avian vocal organ is called the syrinx. The syrinx and sometimes a surrounding air sac resonate to sound waves that are made by membranes past which the bird forces air; the bird controls the pitch by changing the tension on the membranes and controls both pitch and volume by changing the force of exhalation. It can control the two sides of the trachea independently, how some species can produce two notes at once. One of the two main functions of bird song is mate attraction. Scientists hypothesize that bird song evolved through sexual selection, experiments suggest that the quality of bird song may be a good indicator of fitness. Experiments suggest that parasites and diseases may directly affect song characteristics such as song rate, which thereby act as reliable indicators of health.
The song repertoire appears to indicate fitness in some species. The ability of male birds to hold and advertise territories using song demonstrates their fitness. Therefore, a female bird may select males based on the quality of their songs and the size of their song repertoire; the second principal function of bird song is territory defense. Territorial birds will interact with each other using song to negotiate territory boundaries. Since song may be a reliable indicator of quality, individuals may be able to discern the quality of rivals and prevent an energetically costly fight. In birds with song repertoires, individuals may share the same song type and use these song types for more complex communication; some birds will respond to a shared song type with a song-type match. This may be an aggressive signal, however results are mixed. Birds may interact using repertoire-matches, wherein a bird responds with a song type, in its rival's repertoire but is not the song that it is singing; this may be a less aggressive act than song-type matching.
Song complexity is linked to male territorial defense, with more complex songs being perceived as a greater territorial threat. Communication through bird calls can be between individuals of the same species or across species. Birds communicate alarm through vocalizations and movements that are specific to the threat, bird alarms can be understood by other animal species, including other birds, in order to identify and protect against the specific threat. Mobbing calls are used to recruit individuals in an area where an owl or other predator may be present; these calls are characterized by wide-frequency spectra, sharp onset and termination, repetitiveness that are common across species and are believed to be helpful to other potential "mobbers" by being easy to locate. The alarm calls of most species, on the other hand, are characteristically high-pitched, making the caller difficult to locate. Individual birds may be sensitive enough to identify each other through their calls. Many birds t