| 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. |
| Total harmonic distortion (THD) |
| Total harmonic distortion is a measure of non-linear harmonic distortion and is given in %. Non-linear harmonic distortions are signals which were not present in the original before the signal was converted by the headphones. These unwanted signals are caused by the diaphragm, whose movements do not precisely move in time with the electric signals that cause it to move. Unfortunately, this is a feature of all electroacoustic transducers. Although it cannot be completely eliminated, suitable steps can be taken to minimise it. However, the user is not interested in why this distortion takes place but in how great the level of distortion must be for it to become perceptible. According to the findings of several research projects, a total harmonic distortion of 1% in the frequency range of 100 to 2000 Hz is imperceptible. Below 100 Hz, the perceptibility threshold lies at 10%. |
| 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. |
| XLR connector |
| Most common form of connector in audio studio technology. |
