biostudies-literatureZhai SLNorthwestern Polytechnical University Foundation for Basic ResearchNational Natural Science Foundation of ChinaNational Key Scientific Program of ChinaNational Natural Science Foundation of China (National Science Foundation of China)17833https://www.ebi.ac.uk/biostudies/studies/S-EPMC6292856biostudies-literatureUnknown8(1)Music is older than language, and for most of human history music holds our culture together. The pipe instrument is one of the most popular musical instruments of all time. Built on the foundation of previous flute and flute-like acoustic metamaterial models, we herein report the experimental results of the inverse Doppler effects discovered in two common pipe instruments - recorder and clarinet. Our study shows that the inverse Doppler effects can be detected at all seven pitches of an ascending musical scale when there is a relative motion between a microphone (observer) and abovementioned two pipe instruments (source). The calculated effective refractive indices of these two pipe instruments are negative and varying across a set of pitches, exhibiting a desired characteristic of broadbScientific reportsInverse Doppler Effects in Pipe Instruments.PMC6292856118042781167426751272215Shen FLZhai SLLi LLZhao JZhao XPfalseInverse Doppler Effects in Pipe Instruments.Music is older than language, and for most of human history music holds our culture together. The pipe instrument is one of the most popular musical instruments of all time. Built on the foundation of previous flute and flute-like acoustic metamaterial models, we herein report the experimental results of the inverse Doppler effects discovered in two common pipe instruments - recorder and clarinet. Our study shows that the inverse Doppler effects can be detected at all seven pitches of an ascending musical scale when there is a relative motion between a microphone (observer) and abovementioned two pipe instruments (source). The calculated effective refractive indices of these two pipe instruments are negative and varying across a set of pitches, exhibiting a desired characteristic of broadb2018-01-01T00:00:00Z2018 Dec2025-04-04T13:07:43.823Z2019-03-27T00:13:13ZS-EPMC62928563054612210.1038/s41598-018-36517-7