Tag Archives: harmony

New, fast and high-accuracy test developed for COVID-19 infections

Researchers at the University of Washington have developed a new COVID-19 test that has the speed of over-the-counter antigen tests and the accuracy of medical-grade PCR tests.

Image credits Nuttada Panpradist et al., (2022), Science Advances.

Dubbed the ‘Harmony’ test, this diagnostic tool looks for the genetic material of the SARS-CoV-2 virus in test samples. However, unlike PCR tests, which can take several hours to produce a result, the Harmony kit can provide a diagnosis in under 20 minutes with high accuracy.

The test was designed to be low-cost and straightforward to use, according to the authors, in a bid to help everyone, from doctors to the public, to better detect and track coronavirus infections.

New tools

“We designed the test to be low-cost and simple enough that it could be used anywhere,” said Barry Lutz, a UW associate professor of bioengineering, an investigator with the Brotman Baty Institute for Precision Medicine, and senior author of the paper. “We hope that the low cost will make high-performance testing more accessible locally and around the world.”

The Harmony test uses a “PCR-like” approach to detecting the virus — samples are obtained using a nasal swab and processed with ready-to-use reagents using a series of simple steps. The kit is meant to be used with a low-cost detector that can be operated using a smartphone, which provides the results. Each detector can handle up to four samples at a time.

The team explains that one of their main reasons for designing this test kit was the need for affordable and easy-to-use COVID-19 tests that provide reliable accuracy. Many at-home antigen kits available today test for pieces of the virus, not traces of its genetic material, and are only about 80-85% accurate and may be less accurate with the Omicron strain. PCR (polymerase chain reaction) tests are much better — providing around 95% accuracy — but are slow and cannot be carried out at home, as they require specialized devices and training to process. The Harmony kit is meant to combine the strengths of both of these types of tests.

Preliminary results show that Harmony is 97% accurate for nasal swabs. The test detects three different regions of the virus’ genome to help keep it effective against new strains: if a new variant of the virus develops many mutations in one region, the test can still detect the other two. The Harmony kit can detect the Omicron strain.

The step that makes PCR tests so time- and technology-intensive is a series of a few dozen heating and cooling cycles. Temperatures need to be very accurately controlled during these cycles to maintain the integrity of the sample. The Harmony test uses a similar method, known as RT-LAMP (reverse transcription loop-mediated isothermal amplification), with the key difference being that this doesn’t require the same temperature cycling.

“This test operates at a constant temperature, so it eliminates the time to heat and cool and gives results in about 30 minutes,” said Lutz.

Together with two of his colleagues, Lutz set up a new company for the UW — Anavasi Diagnostics — which will take the Harmony kit from an experimental device to a commercially-available product. The team believes that the kit will first be available for clinics and other medical institutions, then in settings where monitoring for infections is required, such as workplaces or schools. After these needs are met, they will adapt the test for home use.

“For a long time, the options have been either a PCR test that is expensive and typically takes a day or more to get a result, or a rapid antigen test that gives fast results and is low cost, but typically has lower accuracy than a lab PCR test,” said Lutz. “From the first day, we designed our test to be manufacturable at low cost and high volume, while delivering fast results with PCR-like performance.”

“We plan to make our test accessible and affordable throughout the world,” he adds.

The paper “Harmony COVID-19: A ready-to-use kit, low-cost detector, and smartphone app for point-of-care SARS-CoV-2 RNA detection” has been published in the journal Science Advances.

“Harmonic surprise”: the secret sauce of chart-topping music

Still from music video for Uptown Funk by Mark Ronson ft. Bruno Mars. Credit: Vevo.

Although writing music is first and foremost a creative endeavor, this doesn’t mean that there aren’t compositional formulas that can dramatically increase the odds of a song sticking in people’s ears. The same thing goes for writing, painting, photography, comedy, and cinematography. Coming back to music, a new study has demystified some aspects that make a song popular, showing that harmonic surprise is an important factor in predicting which piece of music will be perceived as pleasurable.

What’s more, this preference evolves over time as we become accustomed to certain musicalities. Yesterday’s fresh music can grow old, so common harmonies in popular music need to be constantly shifting to catch the listener by surprise.

To reach this conclusion, researchers at Drexel University, Georgetown University, and Loyola University Chicago looked at all the Billboard hits from 1958 to 2019, analyzing the harmonic content of each song. With each passing decade, the harmonic surprise of the top tunes has been increasing, a phenomenon which the researchers have dubbed “inflationary surprise”.

What to write a top pop song? Be different

Why do we like certain pieces of music and dislike others? One prevailing theory is that music evokes a pleasurable response in the human brain depending on the degree to which a song adheres or deviates from what a listener would expect. When we hear familiar songs that sound good to our ears, the brain stimulates a neural reward. This stimulation can equally occur when we hear certain novel types of songs that don’t necessarily adhere to the sound of what we usually listen to.

This notion explains why there is a great deal of variability in musical preferences or why we label some songs as retro and boring while others are fresh and hot. In other words, musical perception is partly based on cultural knowledge.

It follows that surprise in music is an important factor in predicting the popularity of a musical piece. Quantifying a song’s total amount of surprise is possible by analyzing its distinct components, such as harmonies, melody, rhythm, and timbre.

Music that is more likely to cause a pleasurable reaction to listeners tends to place higher on charts, which is why the researchers led by neuroscientist Scott Miles turned to the Billboard Hot 100 as an approximation of popularity and musical reward for their analysis of harmonic surprise.

Previously, in a different study, the researchers proposed two hypotheses as to how surprise affects musical perception. The Absolute-Surprise Hypothesis states that musical popularity is determined by the overall amount of surprise in a piece, based on the notion that dopamine (the ‘feel good’ neurotransmitter) is associated with novelty. The Contrastive-Surprise Hypothesis is not dependent on the total amount of surprise in a song but rather on the contrast between high-surprise and low-surprise sections within a certain song.

In a 2017 study, Miles and colleagues had analyzed the Hot 100 songs, from Bee Gees’ How Deep Is Your Love to Mariah Carey’s We Belong Together, looking for patterns of sounds that may elicit a pleasurable response in the brain. They found that the most popular songs had a high level of harmonic surprise, including the use of rare chords in verse, following by a more conventional, catchy progression in the chorus. Later, the researchers also added other harmonic patterns to their scoring algorithm, including melody, timbre, lyrics, and rhythm, to devise software that can predict if a song will be well received by listeners.

However, this particular study assumed that the “expected” harmony of music was constant over the years across Western popular music — this turned out not to be the case. 

To be successful, a musician needs to be constantly innovating

 Per-song average surprise (in bits), relative to chord distribution of August 1958 to January 1975, of Q1 and Q4 separated into time bins. Error bars represent standard error. Per-song surprise rises faster in Q1 than in Q4. Credit: Frontiers in Neuroscience.

“This assumption, however, may not have been valid; it is entirely possible that the common harmonies which can be reasonably expected to occur in music may change from year to year,” the researchers wrote.

Instead, in this new research, Miles and colleagues went back to the drawing board and devised a more sophisticated model that analyzed how musical perception and preferences evolve over time along with surprising musical content.

They grouped Hot 100 songs into four time “bins” (each spanning about five years of release dates) and calculated the degree of harmonic surprise for each song. This analysis showed that harmonic surprise increases over time and is more pronounced in the most popular hit songs.

“Such dynamic harmonic expectations highlight the interactions between individual listeners and musicians with the culture around them. The Surprise-Inflation Hypothesis raised by the results presented here suggests that the brain’s craving for surprise causes continuous changes in harmonic distributions in popular music. A musician exposed to changes advanced by other musicians must innovate to be successful. It could be that musicians, learning from the success of high-surprise songs from one year, end up producing more high-surprise songs the next year. This could be an explicit strategy to improve on the part of musicians, rather than an implicit change in expectation on the part of the listeners. However, listeners’ preferences change as a result, forcing musicians to incorporate further changes. Hence, the inherent craving for surprise in each of us may push our entire culture in an endless evolution of musical preferences,” the researchers conclude in the journal Frontiers in Human Neuroscience.

chord prevalence

Surprising harmonic structure might be the secret to writing a pop hit, new study finds

music-1874621_960_720

Credit: Pixabay.

Music is literally a rewarding experience which activates neural circuits such as those associated with food or sex. It doesn’t necessarily happen for all kinds of music, though. Why is that? Not much is known about the structural aspects of music that elicit this sort of response — but we seem to be getting there.

Neuroscientists at Georgetown University, Washington, propose two hypotheses that explain why people prefer certain songs over others. The first, called the Absolute-Surprise Hypothesis, simply states that unexpected musical elements or phrases are rewarding. The second, the Contrastive-Surprise Hypothesis, suggests bridging unexpected and subsequent expected events leads to an overall rewarding sensation.

Who doesn’t love a surprise?

The Absolute-Surprise hypothesis is predicated on the notion that surprise is a good thing or valuable for the person perceiving it. Musical surprise, or processing harmonically surprising sections of music, is associated with dopamine release, and therefore with reward response. The Contrastive-Surprise hypothesis, on the other hand, is premised on surprise being bad for the listener, in line with the idea of contrastive valence, which attributes one type of a listener’s enjoyment of music to a release from the tension induced by surprise.

Measuring or quantifying expectations, however, might sound daunting but the team was up to the challenge. Luckily, the researchers had a great helping hand: a useful statistical framework called information theory. This probabilistic framework can offer information about deviations from expectations. As such, within an information theory framework, surprise is nothing more than a  mathematical measure of how much an event deviates from expectations. This means we can use mathematical methods to analyze these expectations and the deviations away from them.

For their paper, the researchers studied available dataset featuring transcriptions of 732 Western popular music songs chosen at random from the Billboard Hot 100 charts over a 34-year period, extending from 1958 to 1991.

“The goal of this statistical analysis is to learn more about how the brain processes music, by examining the structure of music that is preferred. A similar statistical approach has been used to study the neuroscience of the visual system. The principle behind this approach is that one can often explain the mechanisms of a brain sensory system as optimized processors for ecologically important stimuli,” the authors wrote in Frontiers in Human Neuroscience.

In order to examine a single uniform measure of surprise, the researchers were careful to transpose all their songs to a common key, which was C major. Songs that were in a minor key or featured within-song modulations were excluded. In the end, they were left with 545 Billboard songs to analyze.

The next step was to group the songs into quartiles, based on the peak Billboard chart position of each song. The top quartile (Q1) represented widely preferred songs and the bottom quartile (Q4) represented less widely preferred songs.

In both quartiles, the pattern of chord prevalence was strikingly similar, where chord I (the root chord) is followed by V (dominant chord) and IV (sub-dominant chord).

chord prevalence

Credit: Frontiers in Human Neuroscience. 

Moving on to the statistical analysis of the harmonic structure of popular music, the authors determined the mean surprise of songs in top (Q1) and bottom (Q4) quartiles using an equation that essentially determined how varied the chord progression were compared to the mean variations found in the entire corpus of 545 songs.

The authors found Q1 songs had significantly higher overall mean surprise than Q4 songs, which supports the Absolute-surprise Hypothesis, “providing evidence that moderate increases in the absolute level of surprise of a song may indeed drive music preference upward.”

To test the Contrastive-Surprise Hypothesis, the researchers had to analyze the transition between sections, typically verses, choruses and bridges. They measured the standard deviation of average surprise values for the different sections within each song, and then compared the values for Q1 to the corresponding values for Q4.

“Standard deviations of average surprise for sections within individual songs were significantly higher for Q1 than for Q4. Therefore, the Contrastive-surprise Hypothesis is supported by our data, providing evidence that the juxtaposition of high-surprise sections and low-surprise sections may indeed drive music preference upward,” the authors wrote.

“Although these hypotheses seem contradictory to one another, we cannot yet discard the possibility that both absolute and contrastive types of surprise play roles in the enjoyment of popular music. We call this possibility the Hybrid-Surprise Hypothesis,” they concluded.

In other words, people enjoy familiar music as evidenced by the fact that most songs from the Billboard charts use common chord progression. But those songs that we really love and remember, out there in the top quartile, they better be surprising. It’s a familiar theme that’s presented in comedy, literature, painting, and other arts.