A human whistling.
Human whistling is the production of sound by means of carefully controlling a stream of air flowing through a small hole. Whistling can be achieved by creating a small opening with one's lips and then blowing or sucking air through the hole. The air is moderated by the lips, tongue, teeth or fingers (placed over the mouth) to create turbulence, and the mouth acts as a resonant chamber to enhance the resulting sound by acting as a type of Helmholtz resonator. Whistling can also be produced by blowing air through enclosed, cupped hands or through an external instrument, such as a whistle or even a blade of grass or leaf.
Whistling can be musical: many performers on the music hall and Vaudeville circuits were professional whistlers, the most famous of which were Ronnie Ronalde and Fred Lowery. Both had several notable songs featuring whistling.
Pucker whistling is the most common form of whistling used in most Western music. Typically, the tongue tip is lowered, often placed behind the lower teeth, and pitch altered by varying the position of the tongue. In particular, the point at which the tongue body approximates the palate varies from near the uvula (for low notes) to near the alveolar ridge (for high notes). Although varying the degree of pucker will change the pitch of a pucker whistle, expert pucker whistlers will generally only make small variations to the degree of pucker, due to its tendency to affect purity of tone. Pucker whistling can be done by either only blowing out or blowing in and out alternately. In the 'only blow out' method, a consistent tone is achieved, but a negligible pause has to be taken to breathe in. In the alternating method there is no problem of breathlessness or interruption as breath is taken when one whistles breathing in, but a disadvantage is that many times, the consistency of tone is not maintained, and it fluctuates.
Many expert musical palatal whistlers will substantially alter the position of the lips to ensure a good quality tone. Venetian gondoliers are famous for moving the lips while they whistle in a way that can look like singing. A good example of a palatal whistler is Luke Janssen winner of the 2009 world whistling competition.
The term puccalo refers to highly skilled jazz whistling.
The most significant whistling competition is run by the International Whistlers Convention in North Carolina, US. Held every year (recently every other has been in other countries), it brings together whistlers from all over the world who battle for the crown of 'International Grand Champion'.
Apart from being used as simply a method of calling the attention of another (or others), or a musical endeavour, whistling has long been used as a specialized communication between laborers. For example, whistling in theatre, particularly on-stage, is used by flymen to cue the lowering or raising of a batten pipe or flat. This method of communication became popular before the invention of electronic means of communication, and is still in use, primarily in older "hemp" houses during the set and strike of a show. Traditionally, sailors were often used as stage technicians, working with the complicated rope systems associated with flying. Coded whistles would be used to call cues, so it is thought that whistling on-stage may cause, for example, a cue to come early, a "sailor's ghost" to drop a set-piece on top of an actor, or general bad luck in the performance.
Whistling can be used to control trained animals such as dogs.
Whistling as a form of communication
On La Gomera, one of Spain's Canary Islands, a traditional whistled language named Silbo Gomero is still used. Six separate whistling sounds are used to produce two vowels and four consonants, allowing this language to convey more than 4000 words. This language allowed people (e.g. shepherds) to communicate over long distances in the island, when other communication means were not available. It is now taught in school so that it is not lost among the younger generation. Another group of whistlers were the Mazateco Indians of Oaxaca, Mexico. Their whistling aided in conveying messages over far distances, but was also used in close quarters as a unique form of communication with a variety of tones. Busnel & Classe 1976
Many species of birds communicate through vocalizations which are comparable to human whistling. Bird vocalization, like human whistling, is derived from the trachea and is caused by air forced through a hole. The whistle sounds made by some birds are used for various reasons including (but not limited to): mating rituals, food detection, establishing location, etc. Birdsong whistles are also used by humans to identify different bird species. Different rhythms and intonations signify different species and relay different situations. For example, specific birdsongs might imply different geographical locations, or seasons. The Birding by Ear series in the Peterson Field Guides eloquently demonstrate different birdsongs and how they are used not only by birds themselves, but by humans as well.
Whistling is often used by spectators at sporting events to express their opinions of the action taking place before them, but has different meanings depending on where the event takes place. In the United States and Canada, whistling is used much like applause, to express approval or appreciation for the efforts of a team or a player, such as a starting pitcher in baseball who is taken out of the game after having pitched well. Often, a finger whistling technique is used to produce the desired sound.
Conversely, in much of the rest of the world, especially Europe and mostly Brazil, whistling is used to express displeasure with the action or disagreement with an official's decision. This whistling is often loud and cacophonous.
In the UK there is a superstitious belief in the "Seven Whistlers" which are seven mysterious birds or spirits who call out to foretell death or a great calamity. In the 19th century, large groups of coal miners were known to have refused to enter the mines for one day after hearing this spectral whistling. The Seven Whistlers have been mentioned in literature such as The Faerie Queene by Edmund Spenser, as bearing an omen of death. William Wordsworth included fear of the Seven Whistlers in his poem, "Though Narrow Be That Old Man's Cares". The superstition has been reported in the Midland Counties of England but also in Lancashire, Essex, Kent, and even in other places such as North Wales and Portugal.
In Russian and other Slavic cultures (also in Romania and the Baltic states), whistling indoors is superstitiously believed to bring poverty ("whistling money away"), whereas whistling outdoors is considered normal. In Estonia it is also widely believed that whistling indoors may bring bad luck and therefore set the house on fire. 
Whistling on board a sailing ship is thought to encourage the wind strength to increase. This is regularly alluded to in the Aubrey-Maturin books by Patrick O'Brian. A United States Navy saying alluded to a supposition that only homosexuals whistled.
Theater practice has plenty of superstitions: one of them is against whistling.
One of the most well known whistling competitions is the International Whistlers Convention (IWC). Since 1973, this annual event takes place in Louisburg, North Carolina. The awards go to whistlers ranging from international male and female, teenage male and female, and even grandchildren. It has been customary for the Governor of the State of North Carolina to sign a declaration declaring the week of the IWC as "Happy Whistlers Week," for citizens and visitors to honor the art of whistling and to participate in the scheduled events.
- Flo Rida in his hit song "Whistle" from the 2012 album Wild Ones.
- Ronnie Ronalde detailed his musical career in his autobiography entitled Around the World on a Whistle
- Harpo Marx was known to communicate through whistling in both his onstage and on-film roles (such as A Night in Casablanca).
- Roger Whittaker was first known as a musical whistler, e.g. "The Mexican Whistler" released in 1966. A very fast paced & challenging whistling tune.
- Bobbejaan Schoepen, a Flemish entertainer, singer, guitarist, composer, former actor, and founder of one of the most popular theme parks in Europe: Bobbejaanland, was well known for his outstanding whistling, but in the late 1980s he lost the ability due to surgery
- Toots Thielemans is a Belgian jazz artist well known for his guitar, harmonica playing, and also for his highly accomplished professional whistling.
- The Whistler radio series ran from 1942–1948. The show opened with the sound of footsteps and an eerie whistle
- Bing Crosby whistled and trilled in some of his songs, including "White Christmas." He could imitate a birdcall and then riff on it with a swing styling
- Mary Martin in a duet with Bing Crosby on "Wait 'Till the Sun Shines Nellie" in a segment from a 1962 Bing Crosby Christmas special
- Elmo Tanner toured with the Ted Weems Orchestra and whistled in "Heart Aches" and "The High and the Mighty"
- Brother Bones 1903–1974, had a big hit with "Sweet Georgia Brown" which is still used as the warm up music of the Harlem Globetrotters.
- I Was Kaiser Bill's Batman by Whistling Jack Smith was a popular 1967 novelty tune that heavily features whistling
- Andy Offutt Irwin, storyteller, singer-songwriter, and humorist, is able to whistle on both inhalation and exhalation, allowing him to whistle without appearing to take a breath for a minute and a half. Irwin whistling can be heard on his solo performances and albums, but also in appearances with the chamber music group Kandinsky Trio.
- Roy Orbison on "Here Comes the Rain, Baby" from his 1967 album Cry Softly Lonely One
- John Lennon in his song "Jealous Guy" from the album Imagine
- Otis Redding in the last, unfinished verse of his song "(Sittin' On) The Dock of the Bay"
- Peter Bjorn and John on "Young Folks"
- The Black Keys on their song "Tighten Up"
- Andrew Bird implements whistling in many of his songs
- Cirque du Soleil has a touring show named Corteo which features a whistling ringmaster
- The Andy Griffith Show's main TV theme "The Fishin' Hole" is famously whistled by Earle Hagen
- Foster the People in their song "Pumped Up Kicks" prominently features whistling
- Alessandro Alessandroni, an accomplished whistler, collaborated with his childhood friend Ennio Morricone on a number of soundtracks for Spaghetti Westerns.
- Hugo Montenegro had a big hit with "The Good, The Bad, And The Ugly" in 1968. This being the title of the 'Spaghetti Western'.
- Clarence Clemons in Bruce Springsteen's "Working on a Dream"
- Guns N' Roses in their songs "Patience" and "Civil War" features a memorable whistling introduction. In "Civil War", Axl whistles the American Civil War song "When Johnny Comes Marching Home"
- Grizzly Bear in their song "Shift" whistles part of the melody
- Björk in her song "Isobel" uses high pitches whistling discreetly to enhance the eerie mood
- Bobby McFerrin in his song "Don't Worry, Be Happy" (1989), utilizes whistling to promote a happy mood. The chorus is essentially whistling.
- the song "Always Look on the Bright Side of Life" in the movie Monty Python's Life of Brian uses whistling to add to the ironic comedy
- The Beatles song Blackbird uses whistles to emulate the song of the Blackbird
- Sibyl Sanderson Fagan, in her song "A Spring Morning", also emulates bird songs through whistles in order to give the listener a feel for a spring morning
- Graveyard in their song "Longing" from the album Hisingen Blues
- Marquess in their song "Vayamos Companeros" from the album Frenetica
- Edward Sharpe and the Magnetic Zeros use whistling in their song, "Home"
- The Four Knights, "I Love the Sunshine of Your Smile", is a marching style song & features a lot of foot steps and whistling. USA hit in 1951.
- The Chordettes song "Lonely Lips" released in 1955, features whistling
- Guy Mitchell had a catchy USA & UK hit in 1957 with "Knee Deep in The Blues". Whistling is shared about 50/50 with the vocal.
- "Georgie's Theme" from Bernard Herrmann's score for the 1968 film Twisted Nerve, which is also whistled by one-eyed nurse Elle Driver in the hospital corridor scene in Quentin Tarantino's Kill Bill Vol. 1 (2003).
- The lovin' Spoonful song, "Daydream" (1966), features a couple of whistling breaks.
- The introduction to the popular 1999 television series on Cartoon Network Ed, Edd n Eddy, also uses whistling.
- Elvis Costello in the song "A Slow Drag with Josephine" off the album National Ransom uses a whistling solo to conclude the song in a traditional vaudevillian manner.
- The Shadows instrumental, "Stars Fell on Stockton", features whistling at regular interludes.
- Marty Robbins song, "The Story of My Life" has whistling intervals.
Children's television cartoon shows
- Boatswain's call
- Irish whistling champions
- Puirt à beul
- Silbo Gomero language
- Slide whistle
- Tin whistle
- Whistle register
- Whistled language
- Tate (June 30, 2009). "Things Fall Apart – Ch 2". Washington State School for the Blind. Retrieved May 20, 2012.
- "Daily Traditions". Fantastic Asia Ltd. Retrieved May 20, 2012.
- "Belide Tribe 22.000". Indonesia Traveling. Retrieved May 20, 2012.
- GaboudAchk (January 24, 2009). "Evil Eye...... Growing Up". Experience Project. Retrieved May 20, 2012.
- Wright, Elizabeth Mary (1913). Rustic speech and folk-lore. H. Milford. p. 197.
- William Knight, ed. (1883). The poetical works of William Wordsworth 4. Edinburgh: William Paterson. pp. 73–76.
- Notes and Queries, Fifth series (London: Oxford Journals, Oxford University) 2: 264. October 3, 1874 http://books.google.com/books?id=bdyx_f8TT6sC&pg=PA264
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- Taylor, Archer (April 1917). "Three Birds of Ill Omen in British Folklore – III. The Seven Whistlers". Washington University Studies (St Louis, Missouri: Washington University) IV (2): 167–173.
- Passport magazine article
- Gonzalez, N. V. M. "Whistling Up the Wind: Myth and Creativity." Philippine Studies: Historical and Ethnographic Viewpoints 31.2 (1983): 216–226.
- "IWC Main Website".
- Telling Stories, an interview by Greg Davis for Tonic, WUKY, April 28, 2008. Retrieved July 16, 2008.
- Kahn, Ric. "Finally, whistling is cool again", Boston Globe, August 27, 2007
- International Whistlers Convention Main Louisburg Website
- International Whistlers Convention 2008 in Japan Website
- Northern Nightingale site with whistling lessons and links to other whistlers' sites
- Lesson on how to do Palate Whistling
- Whistling in Antiquity (PDF) by A V van Stekelenburg (University of Stellenbosch)
- Indian Whistlers Association (IWA) Website
- Biography page of whistling performer Robert Stemmons with links to other whistlers sites
- YouTube page of professional whistler Dave Santucci featuring whistling performance videos and whistling tutorial videos
- Lecture on the History of Musical Whistling given by Linda Parker Hamilton at the 2012 International Whistlers Convention