Quantum jumps of sound

Amazing stuff! Looks like a clever experiment!

"... Phonons are much larger than photons or electrons, each representing a coordinated group of atoms. Imagine the last note of a piano sonata being held until it naturally fades. While you may hear the sound gradually decline to silence, phonons are actually changing vibrational energy in discrete quantum jumps—like going from a “1 state” (sound) to a “0 state” (no sound). But despite trying for a century, researchers had never been able to observe these jumps.

To make the breakthrough, a team designed a microscopic mechanical resonator that vibrates at a specific frequency when energy is applied, much like a tuning fork. But despite its tiny size, the resonator could vibrate for two milliseconds—a length that, if the resonator were scaled up to the size of a regular tuning fork, would last hours.

As the resonator faded to silence, the team took hundreds of measurements to see when the sound jumped between energy states. To get the readings, they paired the resonator with an electrical detector called a superconducting qubit, which could read out the quantum measurement of the phonon’s energy state (whether it was “0” or “1”). ..."

"In brief: 

• Stanford scientists have confirmed the long-predicted ability of quantum units of sound, or “phonons,” to suddenly change energy levels. 
• The team created a device that takes hundreds of measurements within two milliseconds to pinpoint the moment of a quantum jump.
• The advance has implications for quantum computing and sensing as well as improving everyday technologies, such as smartphones.

..."

From the editor's summary and abstract:

"Editor’s summary

Quantum mechanics predict quantized mechanical energy, but conventional measurements of resonator motion cannot reveal that discreteness. Repeated quantum nondemolition measurements that couple to the discrete energy levels (phonon number) rather than position are required to reveal the quantized jumps in sound. Makihara et al. coupled a lithium niobate mechanical resonator with a superconducting qubit and measured the predicted quantum jumps in phonon number. In addition to the foundational observation, such behavior could be of practical use in quantum information processing based on mechanical quantum systems. ...

Abstract

Quantum mechanics predicts that a vibrating object’s energy comes in discrete packets, yet no measurement of its position reveals this discreteness. Resolving individual energy levels requires a qualitatively different measurement, one coupling to the resonator’s energy rather than its displacement.

We use a superconducting qubit dispersively coupled to a nanomechanical resonator to perform repeated quantum nondemolition measurements of the phonon number. An aligned transfer-print technique integrating the qubit and resonator yields a mechanical lifetime of  milliseconds and a dispersive shift of χπ

 kilohertz per phonon. We heralded single-phonon states with 85% fidelity and observed quantum jumps between the resonator’s first excited state and ground state. These discontinuous transitions are a striking manifestation of quantum mechanics in a massive, vibrating object."

ScienceAdviser

Scientists Catch Sound Making a Quantum Jump With a Microscopic Tuning Fork "Learn how physicists overcame obstacles to watch phonons quantum jump in real-time."

Researchers observe first real-time quantum jump in sound (original news release) "In an experiment, Stanford physicists demonstrated that tiny units of sound can suddenly change energy states, making a quantum jump. This is a long-anticipated breakthrough with the potential to advance a range of technologies."

Quantum jumps of sound

This mechanical resonator, depicted in an illustration (left) and in an image taken by a scanning electron microscope (right), allowed researchers to detect quantum jumps of sound.

Listen to the sounds of the Sun like never before

Amazing stuff! What if the fluctuations of solar activity are the main cause of climate change on earth? I bet it is the case! We still know very little about the sun!

Researchers created sound that can bend itself through space, reaching only your ear in a crowd

Amazing stuff!

"What if you could listen to music or a podcast without headphones or earbuds and without disturbing anyone around you? Or have a private conversation in public without other people hearing you?

Our newly published research introduces a way to create audible enclaves – localized pockets of sound that are isolated from their surroundings. In other words, we’ve developed a technology that could create sound exactly where it needs to be. ..."

"In a new advancement in audio engineering ... has precisely narrowed where sound is perceived by creating localized pockets of sound zones, called audible enclaves. In an enclave, a listener can hear sound, while others standing nearby cannot, even if the people are in an enclosed space, like a vehicle, or standing directly in front of the audio source. ...

“We essentially created a virtual headset,” Zhong said. “Someone within an audible enclave can hear something meant only for them — enabling sound and quiet zones.” ..."

From the significance and abstract:

"Significance

Recent advancements in digital signal processing and loudspeaker array design have enabled us to experience immersive spatial audio in virtual/augmented/extended reality environments in our daily lives. However, further development in audio engineering is impeded by physical constraints stemming from the diffraction of long-wavelength audio waves. This study introduces an approach to address this issue by showcasing the creation of ultrabroadband (125 Hz to 4 kHz) and highly localized remote audio spots, referred to as audible enclaves. By marrying local acoustic nonlinearity with inaudible self-bending ultrasonic beams, the proposed technique overcomes the physical limits in linear acoustics, paving the way for possibilities in future audio engineering.

Abstract

Delivering audible content to a targeted listener without disturbing others is paramount in audio engineering. However, achieving this goal has long been challenging due to the diffraction of low-frequency (long-wavelength) audio waves in linear acoustics.

Here, we introduce an approach for creating remote audio spots, dubbed audible enclaves, by harnessing the local nonlinear interaction of two self-bending ultrasonic beams with distinct spectra. The self-bending ultrasonic beams created by acoustic metasurfaces, though inaudible, can bypass obstacles such as human heads. At their intersection behind obstacles, highly localized audible enclaves are formed due to the local nonlinear interactions. Additionally, we demonstrate the ultrabroadband capabilities of our metasurface-based implementation both numerically and experimentally, spanning from 125 Hz to 4 kHz (6 octave bands), covering the majority of the audible frequency range.

The practicality of our proposed technique is underscored by its compact implementation size (0.16 m, equivalent to 0.06 wavelengths at 125 Hz), as well as its robust performance under wideband transient audio signal excitation and in a common room with reverberations. Our proposed audible enclaves hold significant potential for various applications in advanced audio engineering, including private speech communications, immersive spatial audio reproduction, and high-resolution sound/quiet zone control."

Researchers created sound that can bend itself through space, reaching only your ear in a crowd

‘Audible enclaves’ could enable private listening without headphones (original news release)

Audible enclaves crafted by nonlinear self-bending ultrasonic beams (no public access)

By positioning metasurfaces in front of two ultrasonic transducers, dual ultrasonic waves travel at two slightly different frequencies along a crescent-shaped trajectory until they intersect, forming an audible enclave where sound cab be heard. At other points along the trajectory, sound is not heard — meaning private listening is possible.

How soundwaves make objects levitate in mid-air

Amazing stuff!

Noisy soil: how sound recordings track soil health

Amazing stuff!

Want a better harvest or a nicer looking garden? Play some soil sounds!

Sounds of a happy soil!

"The team ... has found that soundscapes recorded from soil differ depending on its level of restoration. ...

So what do soils sound like?

“It’s basically clicks and crackles and pops, and little clicky sounds that these contact microphones can pick up,” ...

“It’s a reflection of all the little worms and the beetles and the ants and spiders, et cetera, moving around in the soil.” ...

These plots were at varying levels of degradation: 2 had recently been cleared, 2 had been cleared and revegetated 15 years ago, and 2 were remnant vegetation.

“Both the revegetated and reference state sites had a much more diverse soundscape than the degraded soil ...

The researchers are also trialling playing sounds to soil, with early evidence suggesting it helps to encourage better microbe growth. ..."

"Special recordings ... show this chaotic mixture of soundscapes can be a measure of the diversity of tiny living animals in the soil, which create sounds as they move and interact with their environment. ..."

From the abstract:

"Restoring and monitoring soil biodiversity has never been more important. Ecoacoustics is emerging as a promising tool to detect and monitor soil biodiversity and was recently effective in a temperate forest context. However, there is a need to investigate the efficacy of soil ecoacoustics in other ecosystems and bioregions.

Here, we applied ecoacoustics tools and indices (Acoustic Complexity Index, Bioacoustic Index, Normalised Difference Soundscape Index) to measure soil biodiversity in an Australian grassy woodland restoration chronosequence, spanning three age classes. We collected n = 240 soil acoustic samples from two cleared plots (continuously cleared through active management), two woodland plots undergoing restoration (revegetated 14–15 years ago) and two plots of remnant vegetation over 5 days in Mount Bold, South Australia. We used a below-ground sampling device and sound attenuation chamber to record soil invertebrate communities, which were also manually counted.

We found that acoustic complexity and diversity were significantly higher in revegetated and remnant plots than in cleared plots, both in-situ and in sound attenuation chambers. The acoustic complexity and diversity also significantly associated with soil invertebrate abundance and richness.

Synthesis and applications.

Our results provide new support that ecoacoustics can help monitor soil biodiversity in different forest restoration contexts, including in UK temperate and Australian grassy woodlands. This technology holds promise in addressing the global need for effective soil biodiversity monitoring methods and protecting our planet's most diverse ecosystems."

Soil’s noisy: how sound recordings track soil health

Underground ‘rave’ a sign soil is happy

Sounds of the underground reflect soil biodiversity dynamics across a grassy woodland restoration chronosequence (open access)

Fig. 1 Study sites and location (Mount Bold, South Australia).

Caltech Team Develops First Noninvasive Method to Continually Measure True Blood Pressure

Good news! But it is only a promise that needs further validation in practice!

"The new patented technique, called resonance sonomanometry, uses sound waves to gently stimulate resonance in an artery and then uses ultrasound imaging to measure the artery's resonance frequency, arriving at a true measurement of blood pressure. In a small clinical study, the device, which gives patients a gentle buzzing sensation on the skin, produced results akin to those obtained using the standard-of-care blood pressure cuff. ..."

From the abstract:

"Cardiovascular disease is the leading cause of death worldwide. Existing methods for continuous, noninvasive blood pressure (BP) monitoring suffer from poor accuracy, uncomfortable form factors, or a need for frequent calibration, limiting their adoption. We introduce a new framework for continuous BP measurement that is noninvasive and calibration-free called resonance sonomanometry. The method uses ultrasound imaging to measure both the arterial dimensions and artery wall resonances that are induced by acoustic stimulation, which offers a direct measure of BP by a fully determined physical model. The approach and model are validated in vitro using arterial mock-ups and then in multiple arteries in human subjects. This approach offers the promise of robust continuous BP measurements, providing significant benefits for early diagnosis and treatment of cardiovascular disease."

Caltech Team Develops First Noninvasive Method to Continually Measure True Blood Pressure - www.caltech.edu "Solving a decades-old problem, a multidisciplinary team of Caltech researchers has figured out a method to noninvasively and continually measure blood pressure anywhere on the body with next to no disruption to the patient. A device based on the new technique holds the promise to enable better vital-sign monitoring at home, in hospitals, and possibly even in remote locations where resources are limited."

Resonance sonomanometry for noninvasive, continuous monitoring of blood pressure (open access)

Fig.  1 Acoustic stimulation paired with ultrasound imaging reveals resonance properties of an artery. a) Device placement to measure BP in the carotid artery

Two clumsy devices? This does not yet look very practical to me! More work needed?

On HeAR -- Health Acoustic Representations, Google AI could soon use a person’s cough to diagnose disease

Good news! Please cough again your smartphone is listening!

"A team led by Google scientists has developed a machine-learning tool that can help to detect and monitor health conditions by evaluating noises such as coughing and breathing. The artificial intelligence (AI) system1, trained on millions of audio clips of human sounds, might one day be used by physicians to diagnose diseases including COVID-19 and tuberculosis and to assess how well a person’s lungs are functioning. ...

What’s new about the Google system — called Health Acoustic Representations (HeAR) — is the massive data set that it was trained on, and the fact that it can be fine-tuned to perform multiple tasks. ...

Instead, the Google researchers used self-supervised learning, which relies on unlabelled data. Through an automated process, they extracted more than 300 million short sound clips of coughing, breathing, throat clearing and other human sounds from publicly available YouTube videos. ...
“There’s an immense potential not only for diagnosis, but also for screening” and monitoring ..."

From the abstract:

"Health acoustic sounds such as coughs and breaths are known to contain useful health signals with significant potential for monitoring health and disease, yet are underexplored in the medical machine learning community. The existing deep learning systems for health acoustics are often narrowly trained and evaluated on a single task, which is limited by data and may hinder generalization to other tasks. To mitigate these gaps, we develop HeAR, a scalable self-supervised learning-based deep learning system using masked autoencoders trained on a large dataset of 313 million two-second long audio clips. Through linear probes, we establish HeAR as a state-of-the-art health audio embedding model on a benchmark of 33 health acoustic tasks across 6 datasets. By introducing this work, we hope to enable and accelerate further health acoustics research."

[2403.02522] HeAR -- Health Acoustic Representations

Google AI could soon use a person’s cough to diagnose disease Machine-learning system trained on millions of human audio clips shows promise for detecting COVID-19 and tuberculosis.

Credits: Johns Hopkins Bloomberg School of Public Health: Global Health NOW

Turn the beat around: Sony brings 3D sound to livestreams

Sounds interesting! Will there soon also be a 3D hearing aid? 😊👂

"Popstar Hikaru Utada performs Jan. 19 at an online event that Sony bills as the world's first livestreaming to use full object-based spatial sound technology in real time. ..."

Turn the beat around: Sony brings 3D sound to livestreams - Nikkei Asia J-pop star's concert showcases new tech for smartphones and cars

Microsoft Teams now uses AI to improve echo, interruptions, and acoustics

Good news! This should make e.g. video conferencing much better going forward.

"... Microsoft has been testing this for months, measuring its models in the real world to ensure Teams users are noticing the echo reduction and improvements in call quality. The software maker used 30,000 hours of speech to help train its models, and captured thousands of devices through crowd sourcing where Teams users are paid to record their voice and playback audio from their device. ...
“We also simulate about 100,000 different rooms... the room acoustics play a big role in echo cancellation,” says Aichner. The result is big improvements in call audio quality, and an elimination of echo that also allows multiple people to speak at the same time. ..."

Microsoft Teams now uses AI to improve echo, interruptions, and acoustics - The Verge

Moth wings pave the way toward a less-noisy future by inspiring ultra-thin sound absorbers

Amazing stuff! As they say imitation is the sincerest of flattery. This not my first blog about this subject, see here. It appears, we are coming closer to turn the recent discovery of moth acoustic camouflage into practical applications.

"... “What is even more impressive is that the wings are doing this whilst being incredibly thin, with the scale layer being only 1/50th of the thickness of the wavelength of the sound that they are absorbing,” ..."

From the abstract:

"In noise control applications, a perfect metasurface absorber would have the desirable traits of not only mitigating unwanted sound, but also being much thinner than the wavelengths of interest. Such deep-subwavelength performance is difficult to achieve technologically, yet moth wings, as natural metamaterials, offer functionality as efficient sound absorbers through the action of the numerous resonant scales that decorate their wing membrane. Here, we quantify the potential for moth wings to act as a sound-absorbing metasurface coating for acoustically reflective substrates. Moth wings were found to be efficient sound absorbers, reducing reflection from an acoustically hard surface by up to 87% at the lowest frequency tested (20 kHz), despite a thickness to wavelength ratio of up to 1/50. Remarkably, after the removal of the scales from the dorsal surface the wing's orientation on the surface changed its absorptive performance: absorption remains high when the bald wing membrane faces the sound but breaks down almost completely in the reverse orientation. Numerical simulations confirm the strong influence of the air gap below the wing membrane but only when it is adorned with scales. The finding that moth wings act as deep-subwavelength sound-absorbing metasurfaces opens the door to bioinspired, high-performance sound mitigation solutions."

Moth wings pave the way toward a less-noisy future by inspiring ultra-thin sound absorbers Sometimes, copying nature can help us find amazing design ideas.

Moth wings as sound absorber metasurface (open access)

Moth wing-inspired sound absorbing wallpaper in sight after breakthrough Experts at the University of Bristol have discovered that the scales on moth wings act as excellent sound absorbers even when placed on an artificial surface.

Moths draped in stealth acoustic cloak evade bat sonar

Amazing stuff!

"Ultrathin sound absorbers offer lightweight solutions from building acoustics to sonar cloaking. The scales on moth wings have evolved to reduce the echo returning to bats, and we investigate their resonant sound-absorber functionality. Resonant absorbers are most efficient at resonance, and laser Doppler vibrometry (LDV) revealed that an individual moth scale’s three resonance modes indeed span the biosonar frequencies of bats.  ...

Here we investigate moth-scale vibrodynamics to understand their role in creating acoustic camouflage against bat echolocation, where scales on wings provide ultrasound absorber functionality."

Moths draped in stealth acoustic cloak evade bat sonar | Research | Chemistry World Moths can hide from the sonar of feeding bats using their acoustically camouflaged wings. Their evolved stealth adaptation is the result of an array of scales attached to their wing membranes that absorb ultrasound frequencies emitted by hunting bats, and are the first acoustic metamaterials found in nature.

Here is the PNAS paper:

Biomechanics of a moth scale at ultrasonic frequencies