Why this ancient African instrument is music to scientists' ears

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Why this ancient African instrument is music to scientists' ears

Scientists have found a way to detect poison with the help of musical notes

Cape Town bureau chief


An ancient African instrument has inspired a cheap new device that can identify poisonous liquids.
Now it is hoped the mbira sensor — based on a 3,000-year-old instrument also known as a thumb piano — can offer pharmacists in the developing world protection from counterfeit and adulterated drugs.
The World Health Organisation estimates that 10% of medicines in low- and middle-income countries are counterfeit, but instruments to identify fake drugs are expensive and require specialised knowledge to operate.
The mbira device, which can be constructed from off-the-shelf or discarded materials, can accurately measure the density of any liquid. Comparing the density of a suspicious medicine to the density of the known product can reveal whether they have the same ingredients.
The research, by the University of California’s William Grover, was inspired by the observation that sound frequencies created by a musical instrument are determined by its physical properties.
“Could we add a sample to a musical instrument, measure the resulting change in the instrument’s notes, and use this change to determine information about the sample and its properties?” Grover asked in his research paper published in the journal  ACS Omega.
Grover and his team modified a mbira, which consists of graduated metal prongs attached to a soundboard. They replaced the prongs with a length of bent metal tubing, filled it with a liquid, then compared the frequency of the musical notes made by the filled and empty tube to measure the liquid’s density.
When filled with water, the tube played a note that was a tone lower than when it was empty.
Grover then built a new device and, after using it to measure the density of numerous liquids, they decided its first practical application should be to detect diethylene glycol, a poison sometimes used in fake cold medicines to replace glycerol.
The team recorded mbira notes using the two substances using a smartphone, uploaded them to a website they created and found their frequencies differed by 10 hertz — too little for the human ear to detect.
They then tested six different batches of a popular cold and flu medicine and found they made an identical note, suggesting any sample producing a different note must be fake.

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