From wedding guests blocking their ears, to celebrants turning off their own microphones, straight couples are protesting in innovative ways at Australia's law banning gay marriages.

While many are aware that the Howard government changed the Marriage Act in 2004 to prevent same-sex marriage, less known is that the law requires civil celebrants to explain the "nature" of marriage during the ceremony.

Celebrants must tell the gathering: "Marriage, according to law in Australia, is the union of a man and a woman to the exclusion of all others, voluntarily entered into for life" - or words to that effect.

Increasingly, couples and officiators are joining forces to register their displeasure at the law and its requirements.

At Abbey and Mitchell Johnston's wedding in February, guests were asked to cover their ears when celebrant Alison Bartlett read out the offending passage.

Mrs Johnston came up with the idea after being informed over Skype that Ms Bartlett would be legally required to make the pronouncement.

"That just did not sit easy with me," she told Fairfax Media. "It's a matter of equality. I just can't believe we live in a country where it's OK not to have equal rights for everyone."

All attendees at the intimate ceremony enthusiastically blocked their ears, Mrs Johnston said, although they were technically still able to hear the all-important dictum. And Ms Bartlett fulfilled all her statutory duties as a celebrant.

Far from being outspoken, 22-year-old Mrs Johnston is reflective of mainstream opinion, especially among her generational peers. The latest Fairfax/Ipsos polling found 86 per cent of Australians under 25 support gay marriage, and 68 per cent overall. Mrs Johnston's brother made a statement in support of gay marriage at his own wedding.

Rugby union player and marriage equality campaigner David Pocock and his girlfriend Emma Palandri have refused to wed until gay couples are able to do so.

But for couples who desperately want to tie the knot, the Marriage Act can be a blight on their otherwise happy day.

"I'm already fired up about marriage equality and I want to live in a country where everyone's equal," Mrs Johnston said.

"The fact that our personal ceremony had to be dictated by such a bigoted comment ... I couldn't believe that had to be part of our ceremony that was full of love."

Other couples have tried to suppress the statement in other ways, such as coughing over the line as it is uttered, or asking the celebrant to turn the microphone off or down when saying the words.

A more common request is for celebrants to add a qualifying statement after reading out the required section. The wording is arranged with the couple beforehand and typically declares that the newlyweds "look forward to the day when all loving couples are able to marry and celebrate their love the way they are today", or words to that effect.

When Sydneysider Nick Marland, 33, married his wife Melissa last year, their celebrant suggested such a statement. Mr Marland said the wording they agreed on was not "overtly political" but he felt including a message about marriage equality was "a great idea".

"We had a number of gay and lesbian friends at the wedding and we thought it is unfair that we get to celebrate our love here and, as the law stands, they don't," he said.

Ms Bartlett, the Johnston's celebrant, has performed 70 marriages over the past three years and said that most couples were open-minded about same-sex marriage.

She was proud to officiate at ceremonies such as the Johnstons' and to help couples express their support for marriage equality, she said.

The Johnstons' wedding photographer Thomas Stewart said he had seen "various displays of defiance" against the Marriage Act but the Johnstons' was "without doubt the most creative and fun".

"Obviously, it was purely symbolic but the whole thing was a beautiful protest in favour of same-sex marriages being legalised in Australia," he said.

He was overwhelmed by the response on his social media page, he said, and dubbed the stunt "eargate".

A bill is before the Federal Parliament to legalise same-sex marriage and Prime Minister Tony Abbott - though personally opposed - has indicated the Liberal Party will discuss its position following the winter recess.