2.  Compression  Rarefaction  Hearing  Waveform  Frequency  Hertz  Amplitude  Volume  Analog  Digital  Distortion  Cardioid  Hypercardioid  Supercardioid  Bidirectional  Omnidirectional  Condenser  Dynamic  Ribbon  PZM  XLR  TRS  RCA

3.  Audio Basics ◦ Sound  Compression  Rarefaction  Hearing  The Physics of Sound ◦ Frequency  Hertz  Human Hearing Range ◦ Amplitude ◦ Volume ◦ Analog Recording ◦ Digital Recording ◦ Distortion (Audio)  Microphone Polar Patterns ◦ Cardioid ◦ Hypercardioid ◦ Supercardioid ◦ Bidirectional ◦ Omnidirectional  Types of Mics ◦ Condenser ◦ Dynamic ◦ Ribbon ◦ PZM  Cables ◦ XLR ◦ TRS ◦ RCA ◦ Cable Wrapping

4. In this PowerPoint we will cover the physics of sound, the different pick-up patterns used by microphones, some common microphone types, audio cables and their usage. To understand microphones however, first, you must understand sound.

5. Objective(s): When you finish this section you should understand how sound is represented, created and perceived.

6.  Waveform (a representation of sound) ◦ Physics – the shape of a wave, a graph obtained by plotting the instantaneous values of a periodic quantity against time

7.  What is sound? ◦ Sound is a disturbance of air waves caused by the vibration of an object. When an object moves it causes air molecules to push together (compression). As molecules bump into one another they force other air molecules apart (rarefaction).

8.  Hearing ◦ When disrupted air waves enter our ears, our organs of hearing translate them into nerve impulses. The impulses travel to the brain, which interprets them as a sound. ◦ A substance in which sound waves travel is called a sound medium (air, water, solid). Where no sound medium is present, there can be no sound.

9.  If I wave my hand (object) in the air (medium) can you hear it?  Why / Why not?

10.  Frequency ◦ Physics – the number of cycles or completed alternations per unit of time of a wave or oscillation  The standard unit of frequency measurement is hertz (one cycle per second)  Human hearing range: 15hz - 20kHz ◦ Generally: 20hz – 20kHz

11.  Amplitude ◦ Physics – the absolute value of the maximum displacement from a zero value during one period of an oscillation

12.  If I wave my hand (object) in the air (medium) can you hear it?  Why / Why not? ◦ Proximity ◦ Frequency (Speed of vibration) ◦ Amplitude ◦ Human Hearing range: 20hz to 20 kHz

13.  Volume ◦ Science – A measure of loudness of intensity of a sound  Analog Recording ◦ Refers to recording audio in a format of continuous vibrations that are analogous to the original sound waves  Digital Recording ◦ A sequence of discrete samples taken from a continuous sound (audio) waveform and converted into bits (ones and zeros)  Distortion (audio) ◦ Distortion is created by warping (changing) the shape of the original waveform

15. A microphone is an acoustic (sound created without the use of electronics)-to-electric transducer or sensor that converts sound into an electrical signal Invented in 1876 (Emile Berliner) and first used as a telephone voice transmitter

16.  Cardioid – ◦ Cardioid means "heart-shaped” ◦ Sound is picked up mostly from the front and to a lesser extent the sides ◦ Very versatile, ideal for general use ◦ Handheld mics are usually cardioid

17. Hypercardioid Exaggerated version of the cardioid pattern Very directional, eliminates most sound from the sides and rear Often referred to as shotgun microphones Sometimes confused with supercardioid

18. Supercardioid A variation of the cardioid microphone that is most sensitive at the front while rejecting sounds entering 150 degrees to the rear

19. Bi-Directional Uses a figure-eight pattern Picks up sound equally from two opposite directions Primarily used for interviewing. It can be placed between two people facing one another and pick-up each signal

20. Omnidirectional Captures sound equally from all directions

21. Variable Directionality Some microphones allow you to vary the directional characteristics by selecting omni, cardioid or hypercardioid (shotgun) patterns. This feature is sometimes found on video camera microphones, with the idea that you can adjust the directionality to suit the angle of zoom.

22.  Microphone Directional Response Basics (2:43 min)

23. Cardioid Hypercardioid Supercardioid Bi-Directional Omnidirectional

24. Objective(s): At the end of this section you should be able to describe the types of microphones and the situations they are best suited for.

25.  Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. A condenser microphone uses a capacitor to convert acoustical energy into electrical energy.  Condenser microphones are the most common types of microphones you'll find in recording studios. They have a much greater frequency response and transient response - which is the ability to reproduce the "speed" of an instrument or voice. They also generally have a louder output, but are much more sensitive to loud sounds and prone to distortion.

26.  Much higher output levels due to built-in amplifiers  Better transient response ◦ Faster response to rapid changes in spl  Flatter frequency response ◦ Reproduces sound without color, especially in the high end  Require batteries or phantom power from the mixer ◦ Phantom Power is a method of powering microphones by sending DC current (typically 48 volts) over the same mic cable that carries the audio signal. "Phantom" is derived from the fact that there is no visible power cord and the voltage is not perceptible in the audio path.

27. Condenser Use for vocals and acoustic instruments Sensitive: loud sounds or physical damage will cause mic to stop working

28.  Compared to condenser microphones, dynamic microphones are much more rugged. They are especially resistant to moisture and other forms of abuse, which makes them the perfect choice onstage.  Dynamic microphones do not require their own power supply like condenser microphones and their sound quality is generally not as accurate, as they have a limited frequency response, however, this makes them well-suited, along with their ability to withstand high sound pressure levels, for recording loud sounds.

29.  Dynamic ◦ More durable than condensers or ribbons and less expensive ◦ Narrow frequency response ◦ Live performance: stage, outdoors ◦ Use for rough, loud vocals ◦ Rugged, can handle rough handling, moisture and high spl’s better than a condenser POPULAR Shure SM58 Cardioid, used for vocals Shure SM57 Cardioid, used for amplified or acoustic instruments

30. Type of Dynamic microphone Easily damaged Physical shocks can break the ribbon; sneezes, coughs or slamming of case can stretch ribbon  Generally does not use phantom power  Royer R122 ◦ World’s first phantom power active ribbon mic ◦ Greater output than standard ribbons ◦ Used for quiet sources  Acoustic instruments

31.  PZM ◦ Special type of condenser  Consists of a small condenser  microphone mounted face -  down a short distance from the  reflective boundary plate creating a pressure zone  between the plate and the mic. The mic detects  changes in the pressure zone, rather than the  conventional method of detecting changes in the  surrounding air pressure  Works best when placed against a hard, flat surface - often used in conference situations

32.  Elimination of interference from reflected sound waves  Smooth frequency response  Good off-axis consistency  Strong output levels

33.  Condenser ◦ Use for vocals and acoustic instruments ◦ Much higher output levels due to built-in amplifier ◦ Require batteries or phantom power from the mixer ◦ Faster response to rapid changes in spl ◦ Reproduces sound more accurately than other mics  Dynamic ◦ Can withstand loud sounds ◦ Do not require their own power supply ◦ Not as accurate condensers due to a limited frequency response ◦ Rugged ◦ Moisture resistant  Ribbon ◦ Used for quiet sources ◦ Bidirectional dynamic ◦ Generally does not require and external power source (battery or phantom power) ◦ Easily damaged  PZM ◦ Omnidirectional condenser ◦ Eliminates interference from reflected sound waves ◦ Strong output levels ◦ Smooth frequency response

34. Objective(s): After completing this section you should understand the different attributes of audio cables commonly used for video and be able to identify them on site.

35.  XLR ◦ Balanced (3 Wires: hot, cold, ground)) ◦ Used for microphones or equipment with balanced ins and outs ◦ Usable lengths depend of type of mic being used ◦ Male (plug) / Female (jack) connectors  Molded connectors - better  Soldered and screwed connectors do not last as long

36.  TRS (Tip, Ring, Sleeve / 1/4”) ◦ Also, TS and TRRS (iPod, iPhone) ◦ Unbalanced (2 Wires: hot, cold) ◦ Used for instruments, audio equipment, unbalanced microphones ◦ Prone to interference  Keep as short as possible ◦ Usually mono  An exception: stereo headphone plugs 1Sleeve 3Tip 4Ring

37. RCA Unbalanced Keep as short as possible

38. Wrapping Follow natural bias - created by shielding Over and under technique Ties / Connectors

39.  In the presentation we discussed the science of sound, polar patterns, types of microphones and audio cables.

40.  Working in pairs, review the five polar patterns discussed in this powerpoint.  Give at least one example of when each would be the preferred pattern to use when filming. ◦ Ex: An omnidirectional microphone would be better for recording ambient (natural) sound because it would pick up all of the sound in the area without focusing on any particular direction.  Submit to one document with both names on it to Jupiter Grades “Polar Patterns” assignment dropbox.