The highs are soaring higher and the lows are swooping lower among professional singers. But it is male voices that are heading for the stratosphere, while their female counterparts are diving ever deeper.
Across the UK and internationally, male voices in the counter-tenor range and even higher are enjoying fame and acclaim not seen since the saccharine falsetto of the Bee Gees.
Ben Cardew, news editor of Music Week, said: "Antony and the Johnsons are a good example of a strange male artist, singing in this wavering falsetto, who won the Mercury Prize and went on sell 100,000 copies of I Am a Bird Now. People are now generally more accepting of slightly odd things in pop music and that includes the really high voice."
The renaissance of the lofty male voice can be seen in the American neo-soul singer Maxwell, whose high-pitched vocals won him two Grammys for his latest album BLACKsummers'night. Then there's British artist Mika, Muse's lead vocalist Matthew Bellamy, Justin Timberlake, Coldplay's Chris Martin, Wild Beasts' Hayden Thorpe, urban rap star Plan B and R&B singer R Kelly.
Edward Higginbottom, director of music at New College, Oxford, said: "In opera, the really exciting parts are sung by the soprano and it is the same in the pop market. It sounds exotic, rather sort of magical, and impressive that male singers can sing so high. It also has a slightly androgynous effect which is intriguing as a result."
The trend has been mirrored in opera where the public's taste for counter-tenors has been matched by the current vogue for Baroque opera.
Elaine Padmore, director of opera at the Royal Opera House, said: "There are a lot of counter-tenors around now who can sing a whole period of Handel's Baroque operas. It's a slightly eerie voice and people are often surprised that a man's voice can go that high. There's something slightly ethereal about it, something slightly strange and otherworldly."
Cee Lo Green
At this year's Grammy Awards and Brit Awards, Cee Lo Green walked away with the Best Urban/Alternative Performance and Best International Male gongs. Collaborating with DJ/producer Danger Mouse to form Gnarls Barkley, their first single, "Crazy", released in 2006, was an international success.
Sasha Regan's all-male Savoy Operas
Theatre director Sasha Regan's Union Theatre all-male opera company spans the octaves effortlessly. Turning Gilbert and Sullivan's Iolanthe on its head, all the female roles in this political fairy tale are sung by male sopranos, in comically makeshift finery. The production, at Wilton's Music Hall, east London, until 7 May, follows Pirates of Penzance, pictured.
When London rapper Plan B (aka Ben Drew), ditched his hoodie for a slick suit, he took on the alter ego persona of Strickland Banks. By switching to falsetto vocals in bittersweet love songs, the rapper made the Top 10 UK charts and was given A-listed accreditation by Radio 1.
From 2 July at Glyndebourne, East Sussex, counter-tenor Mead will take on the role of Eustazio in Rinaldo, the first opera Handel wrote for the London stage. After winning scholarships to the Royal College of Music, Mead has starred in operas around the globe. Rinaldo is a new production for 2011.
'Jersey Boys' (Ryan Molloy)
Since March 2008, Ryan Molloy has belted out hits by Frankie Valli and the Four Seasons in the West End, as Frankie in Jersey Boys. The musical, first staged on Broadway, opened to great acclaim upon its arrival in the West End in 2008, when it was nominated for five Olivier Awards and took home the gong for Best New Musical. Still running at the Prince Edward Theatre.
As optimistic, high-school teacher Will Schuester in the award-winning Fox comedy musical series Glee, Morrison made it all right for guys to sing high with his renditions of "Don't Stand So Close to Me", "Gold Digger" and "I Wanna Sex You Up". He releases a debut solo album on Mercury Records on 10 May.
Everything Everything (Jonathan Higgs)
This four-piece from Manchester walked away with the South Bank Sky Arts Breakthrough award earlier this year. Fronted by Jonathan Higgs, who sings the falsetto vocals, the band was also nominated for the NME Best New Band gong. Their debut album, Man Alive, was released last year to critical acclaim.
Rising star in every sense, counter-tenor Iestyn Davies sings Oberon in English National Opera's staging of Britten's A Midsummer Night's Dream from 19 May. The production will be set in a 1960s school, Davies taking the role written for Alfred Deller, who first reintroduced the high male voice to an astonished British public.
Despite losing out to Justin Bieber at the Brit Awards (competing for the International Breakthrough Act gong), Bruno Mars was nominated for seven Grammys in February, and took home the award for Best Male Pop Vocal Performance for "Just the Way You Are".
Highs and lows: The women whose voices got deeper
Kate Royal recently performed in The Magic Flute at Royal Opera House and is described by critics as having an extraordinary voice of ethereal beauty. But after giving birth to her son in 2009, she described how the hormonal change in her body subtly lowered her voice. "I accepted that if you work and you are a mother you cannot do everything 100 per cent – something has to give."
Anna Netrebko approaches her 40th birthday in September as mother of a two-year-old. She remains a soprano, but commentators have observed her voice has lowered and "darkened". Last week at the Vienna Staatsoper, she took on a new role as the Donizetti heroine in the title role of the 1830 opera Anna Bolena ("Anne Boleyn"). The role is regarded as the litmus test for the bel canto soprano.
Katherine Jenkins last year discussed her decision to move from full-time soprano to crossover material in the mezzo- soprano range. "It was a singing teacher that thought it would be best for my voice. Then I moved into crossover. And if that makes the music accessible to more people, then great."
The change has paid off for the Welsh singer, with four million album sales, performances for the Pope and the Queen, and a lucrative TV career. She starred in CBS's Dancing with the Stars last Monday with an orchestra and violinist David Garrett, singing "Con te partirò" and "O mio babbino caro".
Jenkins, who has, unusually, carved a singing career outside the opera house, was the first to sing "The Power of Four" at the Six Nations rugby tournament and regularly performs the Welsh national anthem at Welsh rugby union matches.
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