SPL means sound pressure level. In the following article you will read about basics of SPL-measurement. Noise is caused by vibrations of a sound source, such as cords or the loudspeaker diaphragm, and requires for its propagation, a medium, such as air, water or solid bodies. The vibrations of the noise source are transmitted to the medium. These vibrations and pressure fluctuations in the air can perceive our ears as sound. The fullness of what a person can hear is primarily determined by the volume and pitch. Continue reading
Combined heat and power (CHP) is used to generate electricity and provide heat as a waste product. An energy efficiency of over 90% is predicted by the vendor. The electricity-generating engine is fueled primarily by gas. The issue: larger biogas-plants are mostly in massive buildings at a distance of more than 500 meters to the nearest residential area. Smaller plants move ever closer to the vulnerable housing and are housed in part only thirty meters away. Micro-CHP will be even in the basement of homes, schools, hotels and commercial facilities.