Weighing scale
The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented. In its traditional form, it consists of a pivoted horizontal lever with arms of equal lengththe beamand a weighing pan suspended from each arm (hence the plural name ""scales" for a weighing instrument). The unknown mass is placed in one pan and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a more accurate determination of the mass is given by the position of a sliding mass moved along a graduated scale. Technically, a balance compares weight rather than mass, but, in a given gravitational field (such as Earth's gravity), the weight of an object is proportional to its mass, so the standard masses used with balances are usually labeled in units of mass (e.g. g or kg).
History of hearing aids
One of the first digital chips was created by Daniel Graupe. The digital chip, referred to as the Zeta Noise Blocker, routinely adjusted the gain in the frequency channels to help control high levels of noise. The chip was integrated in a number of hearing aids in the 1980s. In addition to the Zeta Noise Blocker, there was a development of digital chips that were devoted to high-speed digital signal processing or DSP. DSP chips became available in 1982, and began to be implemented into hearing aids. By 1988, chips were produced in hearing aids. One of the major contributions of these chips was the ability to process both speech and other types of noises in real time. One major down fall of these chips was that they were massive and used up a lot of battery, which made them nearly impossible to be worn.