| AF sensitivity |
| Specification used for judging the quality of acoustic transducers. A given sound pressure level will generate a certain voltage and vice versa. |
| Audio output level (balanced) |
| Logarithmic value of the audio output voltage based on a standard reference value. A balanced circuit or connection uses separate signal lines for sending a signal, returning the signal and ground (3-pole connection). |
| Audio output level (unbalanced) |
| Logarithmic value of the audio output voltage based on a standard reference value. An unbalanced circuit or connection uses the ground connection (or screening) to return the signal (2-pole connection). |
| Compander |
| Also known as noise reduction system. A system which improves the signal-to-noise ratio by compressing the dynamics on the transmitter side using a compressor, and subsequently restores the normal dynamics on the receiver side using an expander. |
| Frequency response (microphone) |
| The frequency response of a microphone is given within the limits defined by the manufacturer. In studio condenser microphones it is generally within the range of between 20 Hz and 20 kHz. |
| In compliance with |
| Gives the guidelines and requirements which have to be met before a unit can be put onto the market. Such guidelines are published by e.g. standards committees, telecommunications authorities etc. |
| Input voltage range |
| Indicates the voltage range of the input signal within which a unit will work properly, i.e. as specified in its technical data. |
| Peak deviation |
| Maximum permissible deviation for FM. |
| Pick-up pattern |
| Also known as polar pattern, directivity. According to their acoustic design, microphones differ in their sensitivity towards sound from different directions. Pressure microphones have a sensitivity that is largely independent of direction (omni-directional pick-up pattern). Pressure gradient microphones have the pick-up patterns wide cardioid, cardioid, super-cardioid or figure-of-eight. Interference microphones can be used to achieve a further concentration of the pick-up pattern (lobar pick-up pattern). As a special case, dummy head microphones achieve the pick-up pattern of the human ear/head (dummy head stereo). |
| Power supply |
| Description of the power source used for powering a unit, for example mains, battery, rechargeable accupack, etc. |
| RF frequency range |
| The range of frequencies to which a unit (e.g. a receiver) can be tuned. |
| RF output power |
| Output power measured at the antenna socket. |
| Sound pressure level (SPL) |
| Due to the impractical numerical values, the sound pressure is usually given as the logarithmic value of the sound pressure level according to the equation: dB SPL = 20 x log (po / 0.00002 Pa). The abbreviation SPL (sound pressure level) is added in order to make a clear distinction from other uses of dB. The reference sound pressure, which is at the same time the threshold of hearing, is then 0 dB SPL. The threshold of pain is 140 dB SPL. A difference in the sound pressure level of 1 dB is just about perceptible, while a doubling of the sound pressure corresponds to 6 dB and a doubling of the volume corresponds to a rise of 10 dB.
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| Switching bandwidth |
| The frequency band in which frequencies can be switched directly. |
| Transducer principle |
| Two transducer principles have become established for the conversion of electric energy into mechanical energy: electrodynamic and electrostatic transducers, whereby the latter is only to be found in audiophile systems, due to their relatively high manufacturing costs. Electrodynamic transducers basically consist of a ring-shaped permanent magnet and an oscillation coil, which is fixed to the receiver diaphragm. When an audio-frequency alternating current is passed through the oscillation coil, it is caused to vibrate in accordance with the audio-frequency alternating current, thus causing the diaphragm to vibrate in the same way. |
