RESUMO
Introduction: The autonomic nervous system regulates key body functions, such as heart rate, blood pressure, and sweating. Noise exposure can affect the normal functioning of these systems, causing non-auditory health effects. Infrasounds (<20Hz), which cannot be detected by the human ear, are produced daily by many sources, such as vehicles, machines, heating/cooling devices, and household appliances, among others. Some studies have suggested that infrasound can affect the autonomic nervous system, potentially influencing organ function and health. However, more research is needed to understand how infrasound affects these involuntary functions. Objective measures such as heart rate variability, respiratory rate, and electrodermal activity can help assess these physiological effects during exposure to infrasound in the laboratory. However, there are no commercially available speakers or subwoofers that emit frequencies low enough to allow these experiments to be performed. Therefore, to study the non-auditory effects of infrasound in humans through electrophysiological measurements, it is necessary to produce such devices. Objective: To design, produce, and validate a subwoofer that emits infrasound for laboratory use. Methodology: A ported subwoofer was designed (using the online software "SubBox"), which allows for the generation of more vibration and increases the production of lower frequencies. It was produced with a 12-inch speaker and an amplifier to increase the output, which also increases the gain at lower frequencies. After the device was produced, digitally generated sounds were used by a notebook to reproduce the subwoofer for emission of frequencies below 20 kHz. Calibration was performed by a professional electronic engineer. Results: Our findings indicated that the device was capable of producing sounds at frequencies as low as 12 Hz, reaching sound pressure levels of up to 100 dB. Conclusion: The device designed and validated in this research was capable of producing infrasound and, therefore, can be used in the laboratory to study the effects of infrasound on the autonomic nervous system.