Audio Technology Flashcards
Digital recording
Representation of frequency and amplitude through binary system number
Sampling
Periodical samples (voltages) of analog signal at fixed intervals and conversion to digital data
Sampling frequency/Sample rate
The rate at which fixed intervals sample the original signal. 48kHZ - samples 48,000
Most common sampling rates
32, 44.1, 48, 88.2, 96, 176.4, 192
Quantization
As samples of the waveform are taken, these voltages are converted into discrete quantities and assigned values
Bit depth
Digital word length used to represent a given sample and is equivalent to dynamic range
Bit rate
Relationship between sampling frequency and bit depth (bit depth * sampling frequency)
Samplers
Devices that are capable of recording musically transposing, processing and reproducing segments of digitized audio directly from RAM
Digital Audio Tape Systems
DASH, DAT, ADAT, DTRS
The Recordable Compact Disc (CD-R)
Write-once-read-many. Can be recorded on, erased and used again
Digital Versatile Disc (DVD)
Same diameter and thickness as the compact disc but can hold a greater amount of data.
Blu-ray Disc and HD DVD
High density optical disc formats designed to meet demands of HD media
Flash Memory Recorder
Portable digital recorder that has no moving parts and therefore requires no maintenance. Storage medium - memory card, nonvolatile and re-recordable
Secure Digital(SD, SDHX, SDXC)
Industry leading memory cards
Digital audio workstation (DAW)
Expandable recording, mixing, signal processing and editing system that can be integrated with and networked to a collection of devices
Wordclock
Single, master timing reference through which the overall sample-and-hold conversion states during both the record and playback process for all
digital audio channels and devices within the system will occur at exactly the same time
ISDN, Internet2
Allow to produce a recording in real time between studios across town or country with little to no loss in audio quality
AES/EBU
Professional digital audio connection interface. Calls for two audio channels to be encoded in a serial data stream and transmitted through a balanced line using XLR connectors
S/PDIF (Sony/Philips Digital Interface)
Consumer version of AES/EBU. Unbalanced line using phono connectors. (CD players)
SCSI (Small Computer Systems Interface)
Standard for hardware and software command language. Allows two-way communication between, primarily, hard - disk and CD-ROM drives to exchange digital data at fast speeds
iSCSI (Internet SCSI)
Standart based of the Internet Protocol (IP) for linking data storage devices over a network and transferring data by carrying SCSI commands over IP networks
MADI (Multichannel Audio Digital Interface)
Standard used when interfacing multichannel digital audio. Allows up to 56 channels of digital audio to be sent down one coaxial cable
FireWire
Low-cost networking scheme more powerful than SCSI. Powering id flexible, modes are asynchronous/isosynchronous with the same network and compatibility is backward and forward with continuous transmission in either direction.
USB (Universal Serial Bus)
Standardized connection to personal computers of devices such as portable media players, microphones, disk drives, personal digital assistants and smartphones
Thunderbolt
Very high-speed interface also designed to connect peripheral devices to a computer. Uses four cables two each carrying outward and inward data streams. Can transfer a full high-definition movie in 30 sec
Microphones
TRANSDUCERS that convert acoustic energy into electric energy. The device that does the transducing is called the element.
Magnetic Induction
Referred to as dynamic mics. The two types of professional microphones that use this are the moving coil and the ribbon mic.
Variable Capacitance
Referred to as capacitor mics. Requires a power supply in order to operate. Most modern condensers use a
battery or phantom power. However, since the sound of the old tube mics is still preferred, many new versions have appeared with increasing popularity.
Omnidirectional microphone
All around
Bidirectional or figure 8 microphones
Front and rear
Unidirectional
Front. Has several pickup patterns: cardioid, supercardioid, hypercardioid, and ultracardioid or shotgun
Polar response pattern
Microphone’s directional sensitivity that can be displayed
graphically
Frequency response
The range of frequencies that it produces at an
equal level, within a margin of ±3 dB, and can be displayed in a response curve graph.
Sensitivity
Measures the voltage that a microphone produces (dBV), which is an
indication of a microphone’s efficiency
Signal-to-noise ratio (S/N)
The difference between signal and the noise levels in an
electronic component; it is measured in decibels.
Self-noise
The electrical noise, or hiss, a microphone (or any electronic device) produces.
Overload
All microphones will distort if the sound levels are too high
Maximum sound pressure level
The level at which a microphone’s output signal
begins to distort.
Pad
Condenser mics are equipped with this to reduce overloading the mic’s electronics, to help protect against loudness distortion.
Proximity effect
An increase in bass response relative to midrange and treble response – when they are placed close to a
sound source. Directional microphones are susceptible
“humbucking”
Circuit that minimizes the problem of hum (like the Sennheiser MD421)
Lavalier
And other mini-mics are unobtrusive
Shotgun and Parabolic
Used for long-distance pickup
Headset mic
Frees the hands and frontal working space, and keeps
background sound to a minimum by maintaining a close mic-to-source distance
Contact mic or Piezo
Can be attached to a vibrating surface
Boundary mic or pressure zone mic (PZM)
For use on a boundary (a hard reflective surface) so that reflected sounds arrive at the microphone in phase
Noise-canceling mic
For use close to the mouth with excellent rejection
of ambient sound
Wireless mic
For greater mobility in plotting sound pickup.
USB mic
To record directly to a computer without an audio interface
Underwater mic or hydrophone
To record underwater sounds
Windscreens and pop filters
Used to reduce distortion caused by wind and
transients
Shock mount
Built-in shock absorber, is used to prevent
unwanted vibrations from reaching the microphone element
Loudspeakers
Transducers that convert electric energy into sound (acoustic) energy
Moving coil
Most often used loudspeakers
Passive/Active Loudspeakers
Powered externally - passive loudspeakers. Powered internally - active loudspeakers
Woofers and Tweeters
Loudspeakers have drivers large enough to handle the bass frequencies, and drivers small enough to handle the treble frequencies
Crossover network
Separates the bass and treble frequencies at the crossover point and directs them to their particular drivers
Linearity
Frequencies being fed to a loudspeaker at a particular loudness are reproduced at the same level.
Amplifier power
Must be sufficient to drive the loudspeaker system or else distortion,
among other things, will result.
Output-level capability
Studio monitors should have an output-level capability of 110 dB-SPL
Sensitivity
The on-axis sound-pressure level a loudspeaker produces at a given distance
when driven at a certain power (usually at one meter with one watt). Indication of its efficiency.
Polar response
Indicates how a loudspeaker focuses sound at the monitoring position
Arrival time and Phase interference
A sound’s arrival time at the monitoring position should be no more that 1 ms; otherwise, aural perception is impaired because of phase interference.
Polarity
Electrical phase must be maintained between components and systems
Distortion
The appearance of a signal in the reproduced sound that was not in the original sound
Intermodulation distortion (IMD)
Results when two or more frequencies occur at the
same time and interact to create combination tones and dissonances that are unrelated to the original sounds
Harmonic distortion (THD)
Occurs when the audio system introduces harmonics into a recording that where not present originally.
Transient distortion
Relates to the inability of an audio component to respond quickly to a rapidly changing signal, such as that produced by percussive sounds
Loudness distortion
Or overload distortion, results when a signal is recorded or played back at an amplitude greater than the sound system can handle
Full space loudspeaker
A loudspeaker in the middle of the room (full space) generates the least concentrated sound
Soffited loudspeaker
A loudspeaker near a wall or in a wall (soffited) generates more (half space)
Quarter space loudspeaker
A loudspeaker at the intersection of two walls (quarter space), or the intersection of two walls and ceiling (the trihedral corners; 1 eighth space) provides the most.
Equilateral triangle
Positioning where speakers and listener are the corners is the “rule of thumb.”
Near-field monitoring
Enables the sound engineer to reduce the audibility of control room acoustics by placing loudspeakers close to the monitoring position.
Surround sound
Differs from stereo by deepening the depth dimension, thereby placing
the listener more in the center of the aural image than in front of it
Close miking
Places a microphone relatively close to each sound source in an ensemble
Distant miking
Uses two or a few microphones to record an entire ensemble
The 3:1 rule
Microphones should be placed no closer together than three times the distance from any mic to its sound source
Drums recording techniques
Best tone is achieved by miking the top and the bottom of the drum
Acoustic Guitar recording techniques
Because most of an acoustic guitar’s sound radiates from the front of the instrument, a microphone should be somewhere near, and aimed toward the sound hole.
Strings recording techniques
Because the dynamic range of bowed string instruments is not wide, sound has to be reinforced by using several instruments, multiple miking, “double tracking,” or all three
Piano recording techniques
Close miking can create a large stereo sound, distant miking creates a smaller more mono sound
Woodwinds recording techniques
They should be miked far enough away so that the pickup sounds balanced, or multi-miked
Brass recording techniques
Because of their loudness and dynamic range, brass instruments require care in microphone placement (avoiding overload, creating balance and/or separation) and careful attention in adjusting levels at the console (keeping enough headroom) and recorder to avoid overload.
Amplifiers recording techniques
Some electric instruments, such as the bass and guitar, can be recorded either by miking their amplifier speaker or by use of a direct box (DI), or both. A DI is needed for impedance matching. There are two types: active (with an amplifier) and passive (with a transformer). An alternative to using amplifiers for an electric guitar or bass is an amp simulator
Coincident pair (X-Y)
Employs two matched directional microphones
mounted on a vertical axis – with one mic diaphragm directly over the other – and angled apart to aim toward the left and right sides of the sound source.
Near coincident pair
Is the same as coincident but the mics moved
horizontally a few inches apart. This creates a wider image but eventually creates a “hole”
in the middle and must be checked for phase.
Binaural
Recording uses a dummy head with omni mics in the ear canals. This technique can be created with a baffle and two omni mics, but its effect must be heard using headphones.
Blumlein
Similar to the X-Y technique but two bi-directional
(figure-8) mics are used. The distance between microphone and source should be equal to about half the width of the source, so that the angle between microphone axes is 90°.
M-S (middle-side)
Uses a centered coincident microphone pair, although there is a cardioid mic pointed straight at the sound source, while a figure- 8 microphone is pointed sideways, with its front facing left. The figure-8 mic is split to
two mixer channels, the cardioid remains in one. Cardioid plus figure-8 equals LEFT. Cardioid plus out of phase figure-8 equals RIGHT.
Stereo microphone
Contains two capsules in one housing. Usually, you
can rotate the capsules to suit your needs. Phase response is very good but you have relatively little control.
Donut
Fading the music after it is established and reestablishing it later at its former full level to create a hole for the
announcement.
Backtiming
Subtracting the time of an individual item from the total time of a program or program segment
Deadpotting
Playing sound with the fader off
Premix
Is the phase during which dialog, sound effects, and, to some extent, music are prepared for the final rerecording mix
Rerecording mix
To blend the premixed DME tracks into a seamless
stereo or surround sound recording.
