Properties of Sound Loudness

The human ear is a sensitive detector of sound. I had the students explore the perception of the loudness sound. The students measured the relative sensitivity of their ears at various frequencies. The students adjusted the volume on the sound generator to achieve the desired decibels. The decibel levels are displayed on the Visual Analyzer software. For each frequency, the students mark yes when a sound is heard. Most students found that their hearing was most sensitive around 1kHz.

The propagation of sound can be modeled in terms of equations using three basic physic principles: conservation of mass, conservation of momentum and the ideal gas law. The equations that describe these three physic principles can be combined to give the wave equation, which describes the sound field in space and time. The wave equation is an essential aspect of my research, because my research involves modeling sound propagation in bones.

My approach for introducing these principles to the high school community is to initially perform experiments showing when these principles are satisfied. Thereafter, I would explain how they’re related to sound waves. One of my initial steps was to perform a conservation of mass for melting ice cubes. This allowed for a physical demonstration of the principle.

Conservation of mass

The law of Conservation of Mass states that matter is neither created nor destroyed in a physical process. I had the students investigate this law, by having them measure the mass before and after melting ice cubes in a beaker. The measurements agreed with the law. It should be noted that the triple beam balances have to be kept stationary.

what’s going on

Did a mass flow rate experiment with the students last week. This involved a buret graduated cylinder. The basics of it is to measure the mass of water dripping out of the buret in a fraction of time.