In a residential street in south London, dozens of household appliances are being put through their paces - not to measure how well they work, but how loud they sound.

The room we're in is officially a laboratory. There's no soundproofing in sight: noise bounces gleefully off the sort of hard surfaces and shiny floors you'll find in many modern homes.

A device shaped like a human head is rigged up to a monitor displaying colourful graphs, recording every whizz, rattle and beep.

Environmental consultancy firm Quiet Mark has spent the last 10 years awarding its colourful "Q" logo to the quietest household appliances in every category you can think of - from hairdryers and air purifiers to kettles and washing machines.

It's something of a labour of love for founder Poppy Szkiler, whose grandfather, John Connell, established the Noise Abatement Society in 1959.

She says that since the start of the Coronavirus pandemic, people have become a lot more conscious of the noise inside their homes.

"It's becoming a mega-trend," she says.

"People are looking to create more peaceful homes because life has become literally under one roof."

Now the firm, which describes itself as a consumer champion, is looking to change the way we measure sound. Currently when you shop for an appliance, if it does have a noise rating, that figure will be in decibels - and that tells you how loud it is.

Ms Szkiler says about 40 decibels (dB) is ideal for inside the home.

However, 40dB of a smooth, consistent hum is very different from 40dB of clunking, rattling or screeching.

Currently, though, unless you work in the field of acoustic sciences, there's no consumer-friendly measurement for overall sound quality.

Quiet Mark is on a mission to change that and is currently researching ways to include sound quality in the rating it awards the products it assesses.

"In addition to decibels, we are measuring tumble dryers, which often have a big droning sound, and we're measuring jeans - and how the buttons hit the centre of the drum - to measure the sound quality, the pitch and tonality. And we are seeing which appliances are best insulated and isolated, for the best noise reduction within our home," she explains.

There isn't even a term for it yet - but there is a demand.

Quiet Mark is already listed on the sites of various UK retailers, including Argos, Littlewoods and John Lewis.

John Lewis's technology director, Laurence Mitchell, says there are more than 10,000 searches a month for appliances that include the term "quiet" on the retailer's website.

There's a "quiet revolution" tab on John Lewis's appliances page, and washing machines and kettles are the devices most likely to be linked to the search.

But he says consumers should be prepared to pay more for a quieter life.

"If you look at things like appliances, to have a lower noise level you may need things like an inverter direct-drive motor (which reduces the number of motor components, and therefore noise, particularly in washing machines), or increased dampening, and of course those things come with a cost," he says.

Part of the difficulty in finding the right way to label sound quality is that it's such an individual experience - what's music to my ears may be painful to yours.

And on a serious note, continued exposure to loud noise has been linked to health conditions, including heart problems.

People who are neurodiverse may also find some sound challenging.

For example, Tom Purser, of the National Autism Society, says that autistic adults and children process sensory information - including sound - differently.

"For some autistic people, it will mean certain types of noise, certain tones, certain frequencies will be almost painful to them. But for some, there will be certain types of noise and sounds they really enjoy and find themselves seeking," he says.

"It's a very difficult experience when the world is full of so many different sorts of sound and noise on a daily basis."

Poppy Szkiler admits she appreciates the sound of silence - the quieter her home environment, the better for her. She hopes that manufacturers will take note of a wider demand for tech that is seen but barely heard.

"There's huge levels of integrity and wonder in engineering," she says.

"Acoustic engineering is just as important as energy efficiency, or the way something looks, or its performance."