A person who has the skill, expertise and knowledge to undertake audio operations.
2. Draw the audio installation plans for the school Hall PA.
3. Describe the difference between decibels, hertz and electricity.
Decibel levels are a relative measurement for the volume of sound, its loudness; where electricity conducts objects are always full of movable electric charges and electric currents are motions of these charges and finally Hertz are measurements of the frequency of sound vibration. Therefore electricity is constantly running and decibels and hertz are conducted through the sound produced at the current time e.g. Loudness and vibrations.
4. In regards to OHS, describe the term SPL and how it is dangerous for audio technicians.
Sound Pressure Level (SPL) is the loudness of an acoustic wave stated in dB that is proportional to the logarithm of its intensity. It is a measurement of the loudness or 'volume' of a sound.
5. With reference to equalisation, if a room had a ‘boomy’ sound which frequency would you alter to make it less ‘boomy’ and why? High? Med? Low?
The process of equalisation ensure that frequencies are the same in quantity, size or degree throughout the place or group. You would alter the lower frequency to make it less boomy as subtracting it makes the sound more sharp.
6. Using this site and other sites to research and describe the difference between analogue and digital audio mixing desk.
Analogue - electricity produces the sound
digital - sound is converted into a code of '0' and '1'
7. If reference to mixing desks, explain the ratio 24:8:2.
8. Describe the difference between the following terms: Amplitude, decibels, frequency, hertz, watts, voltage and Ohm.
Amplitude - the 'height' of a waveform, heard by the ear as volume. Increasing the amplitude of a noise will make it sound louder.
Decibels - these are figures used to express the volume or Sound Pressure Level (SPL) of a noise. Odb is at the threshold of hearing - only just audible. 40 dB is at normal conversation level. 100 dB is equivalent to the sound of a train passing nearby. 130 dB is the threshold of pain and 150 dB is a jet engine at one metre.
Frequency - the 'speed' of a waveform, heard as pitch, that is, how high or low sounds are to the ear.
Hertz - A measurement of the frequency of sound vibration.
Watts - The unit of electrical power derived from the current multiplied by the voltage.
Voltage - Electric potential energy per unit charge, measures in joules per coulomb
Ohm. - the unit of electrical resistance. For example, the higher the ohm rating of a speaker, the greater the level of signal required to create the same volume from a lower ohm rated speaker.
9. Describe the difference between microphone, line and loudspeaker level.10. Explain the particular uses for the following microphones:
Dynamic: a small movable induction coil, positioned in the magnetic field of a permanent magnet, is attached to the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil. Dynamic microphones are robust and relatively inexpensive and are used in a wide variety of applications.
Condenser: (also known as a capacitor microphone): the diaphragm acts as one plate of a capacitor, and vibrations produce changes in a voltage maintained across the capacitor plates. Condenser microphones are expensive and require an external power supply but give a high-quality sound signal and are used in laboratory and studio recording applications.
Foil: a relatively new type ofcondenser microphone which is now one of the most widely used. They are used in many applications, ranging from high-quality PA to built-in microphones in small sound recording devices. Like other condenser microphones they require an external power supply or a battery. They are frequently phantom-powered in sound reinforcement applications.
Ribbon: a thin, corrugated metal ribbon is suspended in a magnetic field. Vibration of the ribbon in the magnetic field generates a changing voltage. Ribbon microphones detect sound in a bi-directional pattern and this characteristic makes them useful in applications such as radio and television interviews, where it cuts out much extraneous sound.
Boundary: is mounted on a flat plate which acts as a reflective surface directing sound into the microphone capsule. They are used for general pick-up over a large area without as many reflected sound waves to interfere.
PZM (Pressure Zone Microphone): an omnidirectional boundary microphone for picking up sound from all around.
Piezo: uses the phenomenon of piezoelectricity - (that is, the tendency of some materials to produce a voltage when subjected to pressure) to convert vibrations into an electrical signal. This type of microphone is often used to microphone acoustic instruments for live performance (most acoustic/electric guitars use piezo pick-ups) or to record sounds in unusual environments, for example underwater.
11. Draw the 5 direction capability’s of microphones.
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