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Full-Text Articles in Mechanical Engineering
Development Of The Carbon Nanotube Thermoacoustic Loudspeaker, Troy Bouman
Development Of The Carbon Nanotube Thermoacoustic Loudspeaker, Troy Bouman
Dissertations, Master's Theses and Master's Reports
Traditional speakers make sound by attaching a coil to a cone and moving that coil back and forth in a magnetic field (aka moving coil loudspeakers). The physics behind how to generate sound via this velocity boundary condition has largely been unchanged for over a hundred years. Interestingly, around the time moving coil loudspeakers were first investigated the idea of using heat to generate sound was also known. These thermoacoustic speakers heat and cool a thin material at acoustic frequencies to generate the pressure wave (i.e. they use a thermal boundary condition). Unfortunately, when the thermoacoustic principle was initially discovered …
Drive Signal Development For The Thermoacoustic Loudspeaker, Troy Bouman
Drive Signal Development For The Thermoacoustic Loudspeaker, Troy Bouman
Dissertations, Master's Theses and Master's Reports
Carbon nanotube thermophones can create acoustic waves from 1 Hz to 100 kHz. The thermoacoustic effect that allows for this non-vibrating sound source is naturally inefficient. Prior efforts have not explored their true efficiency (i.e. the ratio of the total acoustic power to the electrical input power). All previous works have used the ratio of sound pressure to input electrical power. A method for true power efficiency measurement is shown using a fully anechoic technique. True efficiency data are presented for five different drive signal processing techniques: standard alternating current (AC), direct current added to AC (DCAC), amplitude modulation of …