Families with lower incomes have a 19 percent chance of a child learning an instrument
Their study suggests that lower-social-economic families are half as likely than more affluent families to have a child learning an instrument.
At this London primary school, students are making plenty of noise.
"I like music because it's fun," says one female student.
For classmate Arya Shah, it's her favourite time of the day.
"I like music because there's a lot of loud sounds."
At the age of just six, she hopes that one day music could become a career.
"It's really a beautiful sound and it makes quite a lot of noise and I like noise," she says.
But the concern is not all children are getting the same chances.
For younger children music is compulsory on the UK national curriculum until they are 14 years old. But many state schools and parents simply can't afford the specialist staff needed for one-on-one tuition.
The Musicians' Union research found that families with lower incomes have a 19 percent chance of a child learning an instrument.
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For children from richer families that figure doubles to 40 percent.
The union is calling on the government to help state schools offer more lessons for budding musicians and give music as much weight as other subjects.
"Where you've got a headmaster in a school who really believes in making creative studies offering and believes in music and understands how music can empower young people then you'll find it in the curriculum. But you know academies (independent state funded schools) for instance they don't have to follow the national curriculum and nor do free schools (governed by a non-profit charitable trust)," says Horace Trubridge from the Musicians' Union.
British film composer David Arnold, behind many of the James Bond themes, benefited from being introduced to music at a young age.
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His state school in Luton, outside of London, offered free one-on-one lessons without which he doubts his songs would exist.
"In amongst the academic nature of school, which I was never really all that good at, I found myself in a world that I completely understood and loved and wanted to be involved in. And the fact that you would deny someone the opportunity to be exposed to that and for that to come out of them, I think it's born of a huge amount of ignorance about what music can achieve," says Arnold.
The Department for Education says it has invested 300 million British pounds in music hubs which have helped more than 700,000 students learn an instrument.
But the Musicians' Union says it's still a postcode lottery with the poorest children still missing out.
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