EXPLORING AUDIO TGJ4M Communications Technology

REVIEW: WHAT IS SOUND? Acoustical energy that travels as waves

RECORDING SOUND How do we record sound? Microphones are a type of transducer – a device which converts energy from one form to another Microphones convert acoustical energy (sound waves) into electrical energy (the audio signal)

MICROPHONES Some mics are designed for general use and can be used effectively in many different situations Others are very specialized and are only really useful for their intended purpose Characteristics to look for include directional properties, frequency response and impedance

RECORDING SOUND Mic level is the signal that is typically measured in millivolts Before it can be used for anything serious the signal needs to be amplified, usually to line level Amplification is achieved in one or more ways

SOUND AMPLIFICATION Some microphones have tiny built-in amplifiers which boost the signal to a high mic level or line level The mic can also be fed through a small boosting amplifier, often called a line amp Sound mixers have small amplifiers in each channel The audio signal is fed to a power amplifier - a specialized amp which boosts the signal enough to be fed to loudspeakers

RECORDING SOUND Recording good quality sound requires you to look beyond your camera Most cameras have omnidirectional microphones pick up all sound from every direction Least useful microphones for sound control Override your camera by using an auxiliary microphone

MICROPHONE DIRECTIONALITY How is the directionality of a microphone defined? Mic’s are defined by pick up pattern The range of direction that sound is picked up Omnidirectional Unidirectional Bi-directional PZM (Pressure Zone Mic’s)

OMNIDIRECTIONAL Picks up sound evenly from all (omni) directions In front, behind, beside, below, above Best for ambient sound Sound that comes from all directions Example: the sounds you hear in the street, birds singing, cars passing, wind rustling etc. Ambient noise is sometimes called “atmos” from atmosphere

OMNIDIRECTIONAL Problems These microphones pick up nothing specific and they are difficult to focus Tips for filming record a few minutes of “atmos” to mix with your soundtrack to make other sound recordings more real

UNIDIRECTIONAL Often called “shotgun mics”, or “ gun mics” because of their long shape Designed to pick up sound from the front and rejects sound from the rear Various types defined by the size of their angle of receptivity (narrow vs. broad angle) Cardoid-Heart Shaped Pick Up: Mostly front, some side Example: Handheld Mics

UNIDIRECTIONAL Hypercardoid: exaggerated version of the cardioid pattern. Pick Up: It is very directional and eliminates most sound from the sides and rear. Due to the long thin design of hypercardioids, they are often referred to as shotgun microphones.

UNIDIRECTIONAL USES: Great for picking up specific sounds Captures dialogue but kept off scene (mounted on booms) Problems: Susceptible to handling noise (vibrations caused by mishandling of boom) Require precision-why? off-mic sounds is dull and lacks high frequency. Aim your mic! Cardoid (wide angle) used in interviews need to be pointed at the speaker’s mouth hypercardoid

UNIDIRECTIONAL MICROPHONE TIPS AND TRICKS Reduce noise: Don’t rub the mic with your fingers or handle the cord Keep your pointing in sync Interviews: make sure to aim accordingly Don’t lose control of the mic to random people with no control

BI-DIRECTIONAL Picks up sounds from two opposite sides Good used on a table mount or hanging mount Used for radio shows or other projects that may have live interviews Pick Up: Figure eight

REACH An important consideration Determines how far the microphone can be from the sound source and still have quality sound It may or may not be desirable to have the mic within camera view

IMPEDANCE High impedance microphones are usually quite cheap Their main disadvantage is that they do not perform well over long distance cables In particular a loss of high frequencies

ALTERNATIVE MICROPHONES: PERSONALLY MOUNTED Lavalier Clips (lav or bug mic) Tiny and clipped to clothing Omnidirectional with bass cut to counteract resonance Limited reach (only speaker is heard) Tips and Tricks Mount high for soft spoken individuals Avoid clothing and jewelry rustle

ALTERNATIVE MICROPHONES: PERSONALLY MOUNTED Radio Mic’s Very expensive Use for wide shots and no sight of mic Transmitter with a short antenna sends a signal from the mic to the camera Used for: Recording in difficult situations Ex: Dancing or performing (taped inside costumes or underneath wigs) Problems Batteries wear quickly

BEST PRACTICES Be aware of the circumstances and select the best mic for the job Time of day, activities, specific shooting conditions Test your mic’s before shooting Signal to Noise Ratio Desired signal is loud enough to dominate the background noise Strong signals = clear playback Weak signals = boost of undesired background noise