2023 – the year we actually identified the sound of silence

All year we’ve been keeping our ears to the ground for the latest in the science of sound. Here are 5 things we learned about sound in 2023.

Scientists find the sound of silence

People register silence in the same way they register sounds, according to a study in the PNAS.

1,000 volunteers listened to “auditory illusions” where sounds had been swapped for silence.

In the one-is-more illusion, where people hear a long beep and two short beeps, people regularly report the one-beep sound as being longer (despite both taking up the same amount of time).

When swapped with a long burst of silence or two short bursts, participants in this study reported the same effects. This suggests that, in auditory processing, we hear absences of sound too.

Read more.

Headphones could let us pick which sounds to hear

A team of researchers have developed deep-learning algorithms that let users pick which sounds filter through their noise-cancelling headphones in real time. 

The “semantic hearing” system works by streaming audio from headphones to a connected smartphone, which cancels out all environmental sounds. Then, headphone wearers can select which sounds they want to include through voice commands or a smartphone app.

They presented their findings at the Association for Computing Machinery (ACM) Symposium on User Interface Software and Technology (UIST) 2023.

Read more.

A person wearing noise-cancelling headphones attached to their mobile phone walks through a crowded park.
Credit: University of Washington

Inexplicable sounds heard in the stratosphere

US scientists sent home-made balloons with microphones 20 kilometres into the sky and recorded sounds they couldn’t identify.

The preliminary results of a study were delivered at the 184th Meeting of the Acoustical Society of America in May. They describe mysterious infrasound signals that occur a few times per hour on some flights.

The source of these is completely unknown.

Read more.

Three photos of people inflating solar hot air balloons
The solar hot air balloons being inflated. Credit: Darielle Dexheimer, Sandia National Laboratories.

Languages are louder in the tropics

The physical properties of the very air we breathe – including its temperature – can influence how easy speech is to produce and hear.

study in the journal PNAS found that languages that have a higher average sonority – the loudness of speech sounds – are concentrated around the equator and the Southern Hemisphere.

The higher average annual temperatures tend to lead to a preference for louder, voiced sounds there.

Read more.

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Global distribution of MSIs (mean sonority indexes) across 9,179 language varieties from the ASJP database. Color of dots represents the MSI of the language, with redder dots indicating higher and bluer dots indicating lower indices. The fill color of land areas represents the mean annual temperature. Credit: Wang et al 2023, PNAS Nexus

How does sound work?

Why does the sound of nails on a chalkboard make our skin crawl? Why does a bubbling brook make us calm (if more likely to need to pee)?

In an episode of Podcast Next Gen, Zeph – a year 12 student – wanted to know why some sounds are seemingly fine, but others we hate.

Podcast Next Gen is a collaboration between Cosmos Magazine and the National Youth Science Forum. 

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