Date Thesis Awarded
Bachelors of Science (BS)
Audible anthropogenic noise pollution is widely recognized as a hazard to the natural world. However, airborne ultrasound, a form of human-inaudible noise with a frequency over 20 kHz, is poorly understood and is a potential source of harmful pollution. A few studies have found that chronic airborne ultrasound exposure in industrial settings is associated with subjective effects such as nausea, fatigue, tinnitus, and dizziness. At very high ultrasonic frequencies, eukaryotic cells can lyse. We found that ultrasound commonly exists on the campus of the College of William & Mary (Williamsburg, VA) with the most common ultrasonic tones between 20 to 55 kHz and 13 to 78 dB SPL. We exposed a haploid strain of the budding yeast, Saccharomyces cerevisiae, to environmentally-relevant ultrasound to measure its effects on eukaryotic cells. When exposed to the 40 kHz and > 82 dB SPL ultrasonic environment of our laboratory, colony growth decreased (F1,67 = 10.65, P = 0.002, partial eta-squared effect size = 0.137). Exposure to the 60 kHz and > 82 dB SPL tone of a parametric array speaker did not reduce colony counts (F1,72 = 0.318, P = 0.574, partial eta-squared effect size = 0.004). Finally, exposure to a 40 kHz and 80 dB SPL tone produced by an ultrasonic speaker led to a statistically significant decrease in yeast colony counts (F1,64 = 37.37, P < 0.0001, partial eta-squared effect size = 0.369). Our findings suggest that the ultrasound commonly found in public spaces has the potential to damage eukaryotic cells and reduce cellular growth and division.
Ransone, Elizabeth M., "Exposure to environmentally-relevant levels of ultrasound has biological effects: reduction in the cellular growth of yeast colonies" (2018). Undergraduate Honors Theses. Paper 1209.
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