Sean-nůs (Irish for "old style") is a highly ornamented style of unaccompanied traditional Irish singing. It is one of various sean-nůs activities, which also include sean-nůs dancing. These forms of Irish dance and song have been documented by ethnomusicologists.

Sean-nůs singing:

Sean-nůs singing is a highly-ornamented style of solo singing defined by one source as:

...a rather complex way of singing in Gaelic, confined mainly to some areas in the west and south of the country. It is unaccompanied and has a highly ornamented melodic line....Not all areas have the same type of ornamentation--one finds a very florid line in Connacht, contrasting with a somewhat less decorated one in the south, and, by comparison, a stark simplicity in the northern songs...

” Canainn also says, '...no aspect of Irish music can be fully understood without a deep appreciation of sean-nůs singing. It is the key which opens every lock'.

Traditional Irish sean-nůs songs can be relatively simple. However many are long, extremely stylized and melodically complex. A good performance classically involves substantial ornament and rhythmic variations from verse to verse.

” Canainn characterizes most ornamentation into melismatic ornamentation. This is when a note is replaced or emphasized by a group of adjoining notes, unlike intervallic ornamentation, in which additional notes are used to fill up an interval between two notes.

Decorative elements common in sean-nůs singing include:

"    Highly ornamented where the voice is placed near the top of the range
"    Nasalization (especially in Ulster)
"    A second form of nasalization, used in the south, produces an "m", "n" or "ng" sound at the end of a phrase
"    Brief pauses initiated by glottal stops, "slides" or glissandi (predominantly when sung by women)
"    Very long extended phrases achieved through highly developed breathing control
"    A tendency to draw breath after a conjunction or linking words rather than at the end of a line
"    The ending of some songs by speaking the finishing line instead of singing it
"    Varying of the melody of every verse; this is challenging

All these strategies serve an assortment of purposes, such as:

"    Enhancing a sense of continuity such as by filling the gap between phrases with a nasalized drone
"    Drawing attention to significant words, which is often the purpose of a glottal stop
"    Expressing a transition from the experience of music to the unkind facts of everyday life, through the speaking of the final line at the end of particular songs

A number of songs, especially older ones, are musical mode or modal rather than diatonic in melody. This can present problems for singers who are unfamiliar to the 'layout' of modal scales. Some melodies properly incorporate slightly larger or smaller music intervals than the western standard, but it is rare to hear them performed authentically in the 21st Century.

Distinguishing Social Features:

"    The interaction between the performer and audience is a crucial aspect of the sean-nůs tradition.
"    The singer may require cajoling - this may be considered as part of the recital.
"    The singer may occasionally adopt a position facing the corner of the room and away from the audience, a position that has acoustic benefits and perhaps some ancient significance.
"    The audience is not expected to be silent throughout, and may participate in the performance through words of encouragement and commentary. Sometimes a member of the audience will even come and hold the performer's hand in empathy with the song. Such interaction does not disturb the flow of music, and the performer will often respond to it musically.

Most songs are not gender specific, although the lyrics may imply it is being sung from a woman's or man's point of view. On the other hand there are a few songs that men have a tendency not to sing. Women however do not seem to have the same hesitation.

Modern performance often places songs out of context, and is a new departure for sean-nůs singing.

Content of lyrics:

Many of the songs typically sung sean-nůs could be viewed as forms of love poetry, laments, or references to historical events such as political rebellions or times of famine, lullabies, nature poetry, devotional songs, or combinations of these.

Comic songs are also part of the tradition (e.g., An Spailpin Fanach, Cunnla, Bean Phaidin), as are references to drink (An Bonnan Bui, Preab san Ol, Olaim Puins is Olaim Te).

Language and regional variation:

To the first-time listener, accustomed to pop and classical singers, sean-nůs often sounds more "Arabic" or "Indian" than "Western". There is no evidence however of any non-Western influences.

Sean-nůs singing varies around Ireland, though with the influence of recording media and ease of travel these distinctions are becoming less definite and singers sometimes adopt different styles from various parts of the country. Differences in style generally correspond geographically to the various dialects of Irish, whether from the relatively unadorned and nasal style of the north to the more decorated styles of the south and west. The Waterford Gaeltacht of An Rinn also has a distinct style, despite its small size, which can be heard in the singing of Nioclas Toibin.

The term "sean-nůs" is popularly applied to songs in English and Irish. A large number of sean-nůs songs are macaronic, by which they combine two or more languages. Normally they usually combine Irish and English but occasionally Irish and French or other European languages, including Latin.

Many would agree that it is more the method of singing that is distinctive, and not the lyrics or the language. In spite of this some traditionalist insist that songs exclusively in the English language cannot be regarded as belonging to the tradition.

History of sean-nůs song and modern developments:

The tradition of sean-nůs song was exclusively oral, and remains customarily so. However a few songs were known to have been conveyed to script as early as the 16th century. A songbook for Elizabeth I contained English interpretations of sean-nůs songs. Songs started to be more extensively written down in the eighteenth century; and distributed in print from then on. New composition is a controversial issue within sean-nůs song circles. Some singers insist that the traditional should be supplemented with new material, arguing that since society has changed, then the content of the lyrics should reflect this also. On the other hand, some singers say that only the older, "traditional" songs represent the essence of sean-nůs song - and that therefore deserves a protected, preferential status.

Minimalist means of preserving Irish music and dance:

The practice of sean-nůs dance, sean-nůs song, lilting (also known as "mouth music"), and "the bones" (a simple percussion instrument convenient to carry in a pocket) exists for centuries. It might be interpreted as a minimalist means that helped preserve a musical and dance heritage at a time when musical instruments were too dear for most peasants.

Other Celtic unaccompanied singing styles:

In addition to the unaccompanied Irish traditional sean-nůs singing, Irish lilting is performed without music instruments backing up the singer. A similar tradition in Scotland is Puirt a beul (AKA Diddling).