Audiography Lab (Practical) course : I B.Sc Electronic Media

1. Audiography Lab (Practical)course : I B.Sc Electronic Media G.S.MANOJ BABU B.E.S.,M.SC(EM),PGDAPP.,PGDAPR Assistant Professor, School of Media and Communication A.M.JAIN College, Meenambakkam,Chennai

2. Types of microphones OBJECTIVES • Defines microphone and explain the functioning and working of microphones. • Identify and explain the different types of microphones. • Categorize the microphones based on their polar patterns.

3. CONCEPT • The microphones (mic or mike in short) and the speakers are very common audio equipment. • The work of a microphone and a speaker are opposite of each other. • Basically a microphone has a diaphragm which moves when sound pressure pushes it. • This movement can be converted into proportional voltage using several possible transducers. • A transducer is a device which receives electrical, mechanical or acoustic waves from one medium and converts them into related waves for a similar or different medium. • A microphone (mic) is a transducer that converts acoustical sound energy into electrical energy.

4. CLASSIFICATION Based on Construction / type of transducer used • Condenser Microphone (also capacitor/electrostatic microphone) • Dynamic microphone • Ribbon microphone • Carbon microphone • Piezoelectric microphone • Fiber optic microphone • Laser microphone • MEMS (Micro electrical mechanical system)

5. CLASSIFICATION Based on Pick up or directionality properties 1. Omni-directional 2. Unidirectional 3. Bidirectional

6. MOVING COIL OR DYNAMIC MICROPHONE • Using this electromagnet principle, the dynamic microphone uses a wire coil and magnet to create the audio signal. • The diaphragm is attached to the coil. When the diaphragm vibrates in response to incoming sound waves, the coil moves backwards and forwards past the magnet. This creates a current in the coil which is channeled from the microphone along wires. • Dynamic mics are most useful for close-proximity applications (i.e. 0 to 15 cm) such as lead vocals, guitar amplifiers, etc.

7. Characteristics of DYNAMIC Microphone • Most rugged • Can withstand high-sound levels (input overload) • Can withstand fairly extreme temperatures • No battery needed • Good for vocals and music instruments

8. Ribbon microphone • Ribbon microphones are very similar to magnetic induction units in that they force a magnetic field to transform an acoustic signal into an electric one. • Strong magnets are placed on either side of a very thin strip or "ribbon" of a conductive material,most commonly aluminum. • This material is very light and responds to very little air pressure, the ribbons movement through the magnetic field generates a very small voltage, which can feed a preamp or mixer. Due to the nature of ribbon microphones they can be very preamp dependent.

9. Ribbon microphone • The ribbon material is very thin with a large surface area, blowing into the mic or high wind can damage the ribbon material by causing it to stretch. • The sudden voltage can cause the ribbon to travel beyond its normal range and be damaged.

10. Characteristics of RIBBON Microphone • Sensitive to physical shock • Sensitive to input overload • Sensitive to temperature change • No battery needed • Higher quality sound at greater distances

11. CONDENSER MICROPHONE • A condenser microphone transforms an acoustic signal into an electric one by using capacitor, a two terminal electrical component. • The diaphragm of the microphone is actually used as one element of this capacitor; when the acoustical signal causes the diaphragm to move, the distance between it and the other half of the capacitor is affected, creating the electrical output signal. • Condenser technology is widely used in microphones today and can be found in everything froma karaoke microphone to recording studio microphones.

12. Characteristics of CONDENSER Microphone • Sensitive to phyisical shock • Sensitive to input overload • Sensitive to temperature change • Needs small battery • Higher quality sound at greater distances

13. Carbon microphone • The carbon microphone is seen as a simple device to turn sound into electronic signal. Some examples of their use where in telephones, radio broadcast systems and the popularity was at a peak around the 80's. • Operation of carbon microphone: When a sound wave presses on the conducting diaphragm, the particles of carbon are pressed together and decrease their electrical resistance. • The carbon microphone is working in low power environments.

14. Characteristics of CARBON Microphone • Oldest and simplest microphone that uses carbon dust. • The technology used in the first telephones and is still used in some telephones today. • The carbon dust has a thin metal or plastic diaphragm on one side. As sound waves hit the diaphragm, they compress the carbon dust, which changes its resistance. By running a current through the carbon, the changing resistance changes the amount of current that flows.

15. PIEZOELECTRIC MICROPHONES (CRYSTAL) • Piezoelectric microphones have sensitive crystals that respond to the physical vibration of the acoustic signal coming into the microphone and create the electrical output. While this technology was once used in widely in tape recorders, it is most commonly used today in pickup devices for acoustic instruments.

16. Characteristics of CRYSTAL Microphone • By attaching a diaphragm to a crystal, the crystal will create a signal when sound waves hit the diaphragm. • piezo microphone uses the phenomenon of piezoelectricity—the ability of some materials to produce a voltage when subjected to pressure—to convert vibrations into an electrical signal.

17. LAVALIER MICROPHONE • A lavalier microphone or lavalier (also known as a lav, lapel mic, clip mic, body mic, collar mic, neck mic or personal mic) is a small electret or Ribbon diaphragm used for television, theatre, and public speaking applications in order to allow for hands-free operation.

18. FIBER OPTIC MICROPHONE • A fiber optic microphone converts acoustic waves into electrical signals by sensing changes in light intensity, instead of sensing changes in capacitance or magnetic fields as with conventional microphones. • Fiber optic microphones can be extremely small, and they can be used in electrically sensitive environments. • Fiber optic microphones do not react to or influence any electrical, magnetic, electrostatic or radioactive fields

19. LASER MICROPHONE • A laser microphone is a surveillance device that uses a laser beam to detect sound vibrations in a distant object. It can be used to secretly listen to a conversation with minimal chance of exposure.

20. MICROPHONES: POLAR PATTERN / DIRECTIONALITY • Directionality is a microphones sensitivity to sound relative to the direction or angle from which the sound arrives. • The three basic directional types of microphones are omni directional, unidirectional, and bidirectional.

21. OMNIDIRECTIONAL MICROPHONES • Omni directional microphones are equally sensitive to sound arriving from all angles. Therefore, the microphone does not need to be aimed in any particular direction. • This can be particularly useful when using a lapel mic to capture a speaker’s voice, as the individual can move their head without affecting the sound. • The disadvantage is that an Omni mic cannot be aimed away from undesired sources, such as PA speakers, which may cause feedback. • Applications: studio recording, room microphones, capturing a wide sound source (such as a choir).

22. UNIDIRECTIONAL MICROPHONES • Unidirectional mics are most sensitive to sound arriving from directly in front – the angle referred to as 0 degrees – and less sensitive in other directions. • This makes unidirectional microphones effective at isolating the desired on-axis sound from both unwanted off-axis sound and ambient noise. • Within the unidirectional category, there are three main polar patterns: cardioid, super cardioid, & hypercardioid.

23. a) Cardioid: • Cardioid microphones are most sensitive to sound at the front and least sensitive at the back. • Their unidirectional pickup makes for affective isolation of unwanted ambient sound and high resistance to feedback when compared to omnidirectional alternatives. Applications: Live sound, Studio recording (particularly in less than ideal acoustic environments) b) Super cardioid: • Supercardioid microphones offer a narrower pickup than cardioids and a greater rejection of ambient sound. However, they also pick up a small amount of sound from directly behind. • Supercardioids are highly suited to very loud stage environments as they are very directional with high gain before feedback.

24. c) Hypercardioid: • Hypercardioid options offer narrower front pickup angles than the cardioid – 105 degrees for the hypercardioid – alongside greater rejection of ambient sound. • Additionally, while the cardioid is least sensitive at the rear (180 degrees off-axis), the hypercardioid is least sensitive at 110 degrees. • Applications: Live sound stages where noise levels are high

25. BIDIRECTIONAL (FIGURE OF EIGHT) • 1. A microphone with a figure-of-eight polar pattern picks up the sound from in front of the microphone and from the rear but not the sides (90 degree angle). • 2. Microphones with a figure-of-eight polar pattern are typically ribbon or large diaphragm condenser microphones. • 3. Applications: Studio recording, stereo microphone techniques

27. MIXERS & CONSOLES INTRODUCTION • Mixers, consoles, and control surfaces perform essentially the same basic functions. • They take input signals and route them for monitoring and to output sources, such as broadcast, recording, and Digital Audio Workstations (DAWs). • On the way, depending on how elaborate the device, the signal may be processed with effects such as equalization, compression, limiting, reverberation, and so on. Mixers and consoles differ from control surfaces, however, in the way their signals are delegated.

28. MIXERS • Compared with most studio-sized consoles, mixers are smaller and lighter weight, with limited processing functions that may or may not be computer-assisted. but like consoles they have three basic control sections: input, output, and monitor.

29. CONSOLES • A console (also known as a board, or, in Europe, mixing desk) is typically larger, more complex, and designed for use in a studio. • Most can store operational data and perform several processing functions that are computer-assisted. • Consoles today are available in various configurations; they use different technologies and are designed for specific production purposes. • A console may be analog or digital; appropriate for on-air broadcast, production, or postproduction; and software-based used as a virtual console with a digital audio workstation.

30. ANALOG AND DIGITAL CONSOLES • In an analog console, audio signals flow in and out of physical modules through inboard wires and circuits. To add flexibility to the signal flow, an inboard patch bay consisting of jacks wired to the console’s components facilitates the routing and the rerouting of signals within the console and to and from studio outboard equipment.

31. Digital console • In a digital console, incoming analog audio signals are converted to digital information at the inputs, and Interfaces handle the routing and the signal processing. If the audio entering the console is already digitized, of course no conversion is necessary. • Routing and rerouting of signals are also handled by patching, but operations are managed through the console’s interfaces, which are inboard. There are no jacks or patch cords needed to effect connections.

32. virtual console • A virtual console is a simulated console displayed on a computer screen that is part of the software of a Digital recording program. Its functions are similar to those of a conventional console and are controlled by a mouse or control surface

33. ON-AIR BROADCAST CONSOLES • A console used for on-air broadcasts is designed to handle audio sources that are immediately distributed to the audience. • An on-air broadcast console needs more controlling elements to manage rapid transitions. • In a radio disc jockey program, those transitions are between disc jockey, music, and spot announcements; in an interview or panel program, they are among host, guest(s), call-ins from listeners, and spot announcements.

34. In the three sections basic to all consoles and mixers— input, output, and monitor—the input section of the broadcast console takes an incoming signal from a microphone, CD player, recorder, or phone-in caller. • program, which sends it to the console’s output; to the monitor section so that it can be heard; or to a second monitor system, called audition or cue, which makes it possible to listen to program material while preparing it for broadcast, without its being heard on the air.

35. At the output section, there is a master fader to handle the combined signals feeding to it from the input channels. • This is the last stop at the console before the output signal is further routed and then transmitted. • Signal flow of a basic generic broadcast console.