Search results
Results from the WOW.Com Content Network
Practical impedance-matching devices will generally provide best results over a specified frequency band. The concept of impedance matching is widespread in electrical engineering, but is relevant in other applications in which a form of energy, not necessarily electrical, is transferred between a source and a load, such as in acoustics or optics.
The measurement is given in % and a lower number is better. Rumble The measure of the low frequency (many tens of Hz) noise contributed by the turntable of an analogue playback system. It is caused by imperfect bearings, uneven motor windings, vibrations in driving bands in some turntables, room vibrations (e.g., from traffic) that is ...
Acoustic immittance audiometry - Immittance audiometry is an objective technique which evaluates middle ear function by three procedures: static immittance, tympanometry, and the measurement of acoustic reflex threshold sensitivity. Immittance audiometry is superior to pure tone audiometry in detecting middle ear pathology. Tympanometry
In electronics, an immittance Smith chart can be created by overlaying both the impedance and admittance grids, which is useful for cascading series-connected with parallel-connected electric circuits. This allows for the visualization of changes in impedance or admittance in the system caused by components of either the series or parallel circuit.
The purpose of the middle ear ossicles is to overcome the impedance mismatch between air waves and cochlear waves, by providing impedance matching. Also located in the middle ear are the stapedius muscle and tensor tympani muscle, which protect the hearing mechanism through a stiffening reflex. The stapes transmits sound waves to the inner ear ...
[4] [5] The impedance matching is done through via lever ratios and the ratio of areas of the tympanic membrane and the footplate of the stapes, creating a transformer-like mechanism. [4] Furthermore, the ossicles are arranged in such a manner as to resonate at 700–800 Hz while at the same time protecting the inner ear from excessive energy. [5]
An SWR meter does not measure the actual impedance of a load (the resistance and reactance), but only the mismatch ratio. To measure the actual impedance requires an antenna analyzer or other similar RF measuring device. For accurate readings, the SWR meter itself must also match the line's impedance (typically 50 or 75 Ohms).
The antenna coupling transformer also functioned as an impedance matching transformer, that allowed a better match of the antenna impedance to the rest of the circuit. One or both of the coils usually had several taps which could be selected with a switch, allowing adjustment of the number of turns of that transformer and hence the "turns ratio".