Audio Production 1

Symmetrically

Acoustic imaging is best when the listener, speakers, walls, and other acoustic boundaries are ______________ centered about the listener's position.

Bit Level

Added internal headroom at the ________________ helps reduce errors in level and performance at low-level resolutions whenever multiple audio data streams are mixed or processed within a digital signal processing (DSP) system.

What are the fundamental characteristics of "Waveform"?

Amplitude, Frequency, Velocity, Wavelength, Phase, Harmonic Content, Envelope

Omni-Directional

An __________________ mic is a pressure-operated device that's responsive to sounds which emanate from all directions.

Sample Rate

Analog signal is sampled at discrete and precisely timed intervals as determined by the _______________, the number of measurements that are periodically taken over the course of a second.

Polar Pattern

Angular response can be graphically charted in a way that shows a microphone's sensitivity with respect to direction and frequency over 360°. Such a chart is commonly referred to as the mic's ___________________.

88.2K

As a simple multiple of 44.1, this rate is often used within productions that are intended to be high-resolution products.

Compression

As a vibrating mass moves outward from its normal resting state, it squeezes air molecules into a compressed area, away from the sound source. This causes the area being acted on to have a greater than normal atmospheric pressure, a process called...

Lower Bit Resolution

As multiple signals are mixed together and multiplied (a regular occurrence in gain change and processing functions), ____________________________ numbers play a more important role in determining the signal's overall accuracy and distortion.

Rarefaction

As the vibrating mass moves inward from its normal resting state, an area with a lower-than-normal atmospheric pressure will be created, in a process called...

Rumble

At low frequencies ______________ (high-level vibrations that occur in the 3 to 25 Hz region) can be easily introduced into the surface of a large unsupported floor space, studio, or hall from any number of sources.

Interaural Arrival-Time Difference

At lower frequencies, where wavelengths are large compared to the head's diameter, waves easily bend around its acoustic shadow creating small time differences. This is called ____________________________________________________________.

Binary Number System

Digital audio is simply a process by which numeric representations of analog signals (in the form of voltage levels) are encoded, processed, stored and reproduced over time through the use of a ______________________________.

What occurs when the sample rate is set too low?

Important data between sample periods will be lost.

Bi-Directional

In a _______________ polar pattern (commonly called a figure-8 pattern), the diaphragm is exposed to sound waves from both the front and rear axis, and is equally sensitive to sounds that emanate from either direction.

Unbalanced

In an ________________ circuit, a single signal lead carries a positive current potential to a device, while a second, grounded sheild (which is tied to the chassis ground) is used to complete the circuit's return path.

Nyquist Theorem

In order for the desired frequency bandwidth to be faithfully encoded in the digital domain, the selected sample rate must be at least twice as high as the highest frequency to be recorded.

Mechanical Vibrations

In the ear-drum, a stretched drum-like membrane, sound waves are changed into __________.

Describe the process of D/A conversion.

Increasing the effective sample rate by factors ranging between 12 and 128 times the original rate.

Overload Distortion

Just as a microphone is limited at low levels by its inherent self-noise, it's also limited at high sound-pressure levels (SPLs) by ____________________________.

Hertz

The number of cycles that occur within a second (frequency) is measured in ________

Frequency

The rate at which a vibration repeats within a cycle of positive and negative amplitude is known as the ________ of that signal.

Transmission Loss

The reduction in SPL of a sound source as it passes through an acoustic barrier of a certain physical mass is termed the ____________ of a signal.

Decibel

The unit used for measuring sound-pressure level (SPL), signal level and relative changes in signal level is the __________, a term that literally means 1/10th of a Bell (an older telephone transmission loss measurement unit that was named after Alexander Graham Bell, inventor of the telephone).

Acoustic Trauma

This happens when the ear is exposed to a sudden, loud noise in excess of 140 dB. Such a shock could lead to permanent hearing loss.

192K

This high-resolution rate is uncommon within pro audio production, as the storage and media requirements are quite high.

96K

This rate has been adopted as the de facto sample rate for high-resolution recordings.

32K

This rate is often used by broadcasters to transmit/receive digital data via satellite. With its overall 15-kHz bandwidth and reduced data requirements, it is also used by certain devices in order to conserve on memory and is commonly used in satellite broadcast communications.

48K

This standard was adopted early on as a standard sample rate for professional audio applications (particularly when referring to hardware digital audio devices). It's also the adopted standard rate for use within professional video and DVD production.

Low Pass Filter

To eliminate the effects of aliasing, a _____________________ is placed into the circuit before the sampling process takes place.

1000

Turning something up by 10 dB will increase the signal's level 10-fold, 20 dB will yield a 100-fold increase, 30 dB will yield a ________- fold increase.

Double

Turning something up by 3 dB will __________ the signal's level.

Beats

Two tones that differ only slightly in frequency and have approximately the same amplitude will produce an effect known as ___________.

Out of Phase

Two wave-forms that have similar amplitudes and frequency, but start their cyclic periods at different times are said to be _______ with respect to each other.

Phase

Variations in _________, are measured in degrees (°), and can be described as a time delay between two or more waveforms with differences over the full rotation of a cycle (e.g., 90°, 180°, 270°, or any angle between 0° and 360°).

Cochlea

Vibrations are then applied to the inner ear or ___________ - a tubular, snail-like organ that contains two fluid-filled chambers.

The physical length of a wave can be calculated using what formula?

Wavelength = Velocity / Frequency

Early Reflection

Waves that bounce off of surrounding surfaces in a room, arriving less than 50 msec after the direct sound, and from a multitude of directions are called _____________.

Higher Sample Rate

Since a true "brick wall" doesn't exist, a __________________________ must be chosen in order to account for the cutoff slope that's required for the filter to be effective.

Preamp

Since the output signals of most microphones are at levels far too low to drive the line-level input stage of most recording systems, a mic ___________ must be used to boost its signal to acceptable levels (often by 30 to 70 dB).

Simple Waves

Sine waves, square waves, triangle waves and sawtooth waves are examples of _________ that contain a consistent harmonic structure.

TDIF

Tascam Digital Interface The TDIF is a proprietary format that uses a 25-pin D-sub cable to transmit and/or receive up to eight channels of digital audio between compatible devices.

ADAT Lightpipe

The Alesis lightpipe is used for transmitting multichannel audio via a standardized optical cable link.

Decay Time or Reverb Time

The time it takes for a reverberant sound to decrease to 60 dB below its original level is called its ________________________ or ________________________________ and is determined by the room's absorption characteristics.

Period

The time it takes to complete 1 cycle is called the _______ of the wave.

Sonic Reflections

The control of __________ within a space is an important factor for maximizing the intelligibility of music and speech.

Peak-to-Peak Value

The total measurement of the positive and negative peak signal levels is called the...

Hold

The converter stores the representative word into a memory medium, release its _______, and then go about the task of determining the values of the next sampled voltage.

Peak Amplitude Value

The measurement of either the maximum positive or negative signal level of a wave is called its _________ (or peak level).

Signal-to-Error Ratio

16 Bit Word = 97.8 dB 24 Bit Word = 145.8 dB 32 Bit Word = 193.8 dB 64 Bit Word = 385.8 dB

AES/EBU

AES - Audio Engineering Society EBU - European Broadcast Union The AES/EBU protocol has been adopted for the purpose of transmitting digital audio between professional digital audio devices.

Standing Waves

Rooms that include opposing parallel walls in their design give rise to a phenomenon known as _____________, and should be avoided at all costs.

Describe the Sampling Process.

1: Sampling an analog voltage signal at precise intervals in time. 2: Converting these samples into a digital word value that most accurately represents these voltage levels. 3: Storing them within a digital memory device

Calculating Bit Depth

8 Bit Word = (nnnnnnnn) = 256 Steps 16 Bit Word = (nnnnnnnn nnnnnnnn) = 65,536 20 Bit Word = (nnnnnnnn nnnnnnnn nnnn) = 1,048,576 24 Bit Word = (nnnnnnnn nnnnnnnn nnnnnnnn) = 16,777,216 32 Bit Word = (nnnnnnnn nnnnnnnn nnnnnnnn nnnnnnnn) = 4,294,967,296

Bass Traps

Absorbers that can be used to reduce low frequency buildup at specific resonant frequencies (and their multiples) within a room are known as _____________.

Flat

A ________ indicates that the device passes all frequencies equally (with no frequency being emphasized or de-emphasized).

Sine Wave

A ________ is composed of a single frequency that produces a pure sound at a specific pitch.

90° Corner

A __________ will reflect sound back in the same direction as it's incident source.

Microphone

A _______________ is usually the first device in a recording chain. Essentially, it is a transducer that changes one form of energy (sound waves) into another corresponding form of energy (electrical signals).

Balanced

A _______________ line uses three wires to properly carry the audio signal. Two of the wires are used to carry the signal voltage, while a third lead is used as a neutral ground wire.

Cardioid

A bi-directional (pressure-gradient) and omnidirectional (pressure) pickup can be combined to obtain other directional pattern types, with the most widely known patterns being the _________ polar patterns.

Sampling

A digital audio system works by ____________ (measuring) the instantaneous voltage level of an analog signal at specific intervals over time, and then converting into a series of encoded "words" that digitally represent the analogous voltage levels.

Waveform

A graphic representation of a sound-pressure level as it moves through a medium over time is called a...

Sensitivity Rating

A mic's __________________ is the output level (in volts) that a microphone will produce, given a specific and standardized acoustic signal at its input (rated in dB SPL).

Output Characteristics

A microphone's ________________________ refer to its measured sensitivity, equivalent noise, overload characteristics, impedance and other output responses.

Upper Limit

A recording made at a higher sample rate will be capable of storing a wider range of frequencies, increasing the signal's bandwidth at its ________________.

Flat Frequency Response

A room should exhibit a relatively ___________ over the entire audio range without adding it's own particular sound coloration.

Soffit

A specially designed cavity called a ________________ can be designed into the front-facing wall of the control room to house the larger studio monitors, allowing them to be mounted directly into the wall to reduce reflections and resonances in the monitoring environment.

Direct Sound

A wave that travels from the source to the listener following the shortest path and arriving at the listener's ear first is called the ___________.

Panning

By changing the proportion that's sent to each speaker, the engineer changes the relative interaural intensity differences and thus creates the illusion of physical positioning between the speakers. This placement technique is known as ___________.

Describe Dither.

Commonly used during the recording or conversion process to increase the overall bit resolution of a recorded signal when converting from a higher to a lower bit rate.

Word Clock

Due to the need for locking (synchronizing) the sample clocks within a connected digital audio system to a common timing reference, a single master timing reference known as _________________ can maintain that conversion states during record and playback for all digital audio channels and devices within the system will occur at exactly the same point in time.

Temporal Fusion

Early reflections arriving at the listener within 30 msec (subject to envelope of the sound) of the direct sound are not only audibly suppressed, but are also fused with the direct sound. This is called ___________.

Permanent Threshold Shift

Extended exposure to loud noises in a specific or broad hearing range can lead to permanent hearing loss in that range, becoming less sensitive to sounds in the damaged frequency range, and leading to a reduction in perceived volume. This is called _________.

Float

If a location has considerable neighborhood noise, you might have to resort to extensive construction techniques that can ___________ the rooms (a process that effectively isolates and uncouples the inner rooms from the building's outer foundation).

Jitter

If data is to be distributed throughout a connected network of digital cables between devices, varying time delays (typically clocking issues) in the circuit paths from component to component in the signal path can introduce time-base errors known as ____________ into the path, with the possible side effects being added noise, distortion and a slightly "blurred" signal image.

Quantization Errors

If the bit rate is too low to accurately encode the sample, the resolution will lead to _____________________________, which will lead to distortion.

85 dB SPL

It has generally been found that changes in apparent frequency balance are less apparent when monitoring at levels of ________.

Interaural Intensity Difference

Middle to high frequency sounds originating from the right side will reach the right ear at a higher intensity level than the left ear, causing an ____________________________________________________.

What occurs as the sample rate increases?

More frequency-related data can be encoded.

Partitions

Movable acoustic __________ (also called flats or gobos) are commonly used in studios to provide on-the-spot barriers to sound leakage.

Equal to

Much like a light wave, sound reflects off a surface boundary at an angle that's _________ (and in an opposite direction of) its initial angle of incidence.

MADI

Multichannel Audio Digital Interface The MADI standard was jointly proposed as an AES standard by representatives of Never, Sony, and SSL as a straightforward, clutter-free digital interface between multitrack devices.

Cycle

One completed excursion of a wave (single compression and rarefaction plotted over the 360° axis of a circle) is known as a ________

Harmonics

Overtone frequencies that are whole-number multiples of the fundamental frequency are called ________.

Overtones

Partials that are higher than the fundamental frequency are called upper partials or _______.

Alias

Should frequencies that are greater than twice the sample rate be allowed into the sampling process, these high frequencies would have a periodic nature that's shorter than the sample rate can actually capture. When this happens, the successive samples won't be able to accurately capture these higher frequencies, and will instead actually record false or "__________" frequencies that aren't actually there, but will be heard as harmonic distortion.

S/PDIF

Sony/Phillips Digital Interface The S/PDIF protocol has been widely adopted for transmitting digital audio between consumer digital audio devices and their professional counterparts.

Sound-Pressure Waves

Sound arrives at the ear in the form of periodic variations in atmospheric pressure called...

Hammer, Anvil, Stirrups

Sound is transferred to the inner ear by way of three bones known as the __________, __________, and __________.

Wave Propagation

Sound waves move through in the form of high-pressure compression waves that continue to push against areas of lower pressure (in an outward direction). This outward pressure motion is known as...

Threshold of Pain

The SPL that causes pain in a listener 50% of the time is called the _________ and corresponds to an SPL of 140 dB in the frequency range between 200 Hz and 10 kHz.

Threshold of Sensation

The ________ occurs at a level of about 118 dB SPL between the frequencies of 200 Hz and 10 kHz, and causes discomfort in a listener 50% of the time.

Wavelength

The ________ of a waveform (frequently represented by the Greek letter lambda, y) is the physical distance in a medium between the beginning and the end of a cycle.

Envelope

The ________ of a waveform can be described as characteristic variations in level that occur in time over the duration of a played note.

Root-Mean-Square

The ________ value was developed to determine a meaningful average level of a waveform over time by squaring the amplitudes at points along the waveform and then taking the mathematical average of the combined results.

Fletcher-Munson Equal-Loudness

The _________ contour curves indicate the ear's average sensitivity to different frequencies at various levels.

Ribbon

The _________ mic also works on the principle of electromagnetic induction, using a diaphragm of extremely thin aluminum ribbon, often, corrugated along its width and suspended within a strong field of magnetic flux.

Dynamic

The _________ mic operates by using electromagnetic induction to generate an output signal.

Velocity

The _________ of a sound wave as it travels through air at 68°F (room temperature) is approximately 1130 feet per second (ft/sec).

Frequency

The __________ components of a room shouldn't adversely affect the acoustic balance of instruments and/or speakers.

Pinna

The __________ make use of two ridges that reflect sound into the ear, introducing minute time delays between the direct sound and the sound that's reflected from the ridge indicating if the sound originates from the front, behind or below.

Threshold of Hearing

The __________ which is the minimum sound pressure that produces the phenomenon of hearing in most people and is equal to 0.0002 microbar (1 microbar is equal to 1 millionth of normal atmospheric pressure), and is usually denoted as 0 dB SPL.

Bit Rate

The _____________ of a digitally recorded sound file relates to the number of quantization steps that are encoded into the bitstream, directly correlated to the accuracy at which a sampled level (at one point in time) is to be encoded, and the overall dynamic range of the recorded signal.

Directional Response

The ____________________ of a mic refers to its sensitivity (output level) at various angles of incidence with respect to the front (on-axis) of the microphone.

Equivalent Noise Rating

The _____________________________ of a microphone can be viewed as the device's electrical self-noise.

Separation

The acoustic environment should not interfere with intelligibility and should offer the highest possible degree of ________________ within the room.

Bit Rate

The analog signal is momentarily "held", while the converter determines what the voltage level actually is, with a degree of accuracy that's defined by the converter's circuitry and the chosen _______________.

Psychoacoustics

The area of ______________ deals with how and why the brain interprets a particular sound stimulus in a certain way.

Spatial Localization

The capability of two ears to localize a sound source within an acoustic space is called _______________.

Frequency Response Curve

The charted output of an audio device, used to graphically represent how a device will respond to the audio spectrum and, thus, how it will affect a signal's overall sound, is known as its _________ (when supplied with a reference input of equal level over the 20-20,000Hz range of human hearing.)

Amplitude

The distance above or below the centerline of a waveform represents the ______________ level of that signal.

Temporary Threshold Shift

The ear can experience temporary hearing loss when exposed to long-term, loud noise. This is called ____________.

Octave

The ear perceives frequencies that are whole, doubled multiples of the fundamental as being related in a special way (a phenomenon known as the musical _______).

Partials

The factor that helps us differentiate between instrumental "voicings" is the presence of frequencies (called ________) that exist in addition to the fundamental pitch that's being played.

Least Significant Bit

The final and smallest numeric value within a digital word is called the _________________________.

Timbre

The harmonics and their relative intensities (which determine an instrument's characteristic sound) are called the _________ of an instrument.

44.1K

The long-time standard of consumer and pro audio production, 44.1 is the chosen rate of the CD-audio standard. With its overall 20-kHz bandwidth, the 44.1k rate is generally considered to be the minimum sample rate for professional audio production. Assuming that high-quality converters are used, this rate is capable of recording lossless audio, while conserving on memory storage requirements. This high-resolution rate is uncommon within pro audio production, as the storage and media requirements are quite high.

Number of Zeros

When a number is an integral power of 10 (e.g., 100, 1000, 10000), the log can be found simply by adding up the _________.

Heat

When neighboring sets of molecules have been compressed, they will continue to exert an outward force on the next set of lower-pressured neighbors in an ongoing outward motion that continues until the molecules have used up all their energy in the form of...

Decreases

When the frequency is increased, the wavelength _________

Pinna

When these variations arrive at the listener, sound-pressure waves are collected in the aural canal by way of the outer ear's __________.

Sound Lock

Whenever possible, double door designs should be used to form an acoustical _________________.

1 to 2 ft away

Whenever possible, speaker enclosures should be placed _________________ from the nearest wall and/or corner to help prevent bass buildups that occur at boundary and corner locations.

Reverberation

Whenever room reflections continue to bounce off of room boundaries, a randomly decaying set of sounds can often be heard after the source stops in the form of __________.

Absorption Coefficient

Whenever sound strikes a material, the amount of acoustic energy that's absorbed relative to the amount that's reflected can be expressed in a simple ration known as the material's _______________.

In Phase

Whenever two waveforms having the same frequency, shape and peak amplitude are completely ______ (meaning that they have no relative time difference), the newly combined waveform will have the same frequency, phase and shape, but will be double in amplitude.

Sustain

__________ refers to the duration of the ongoing sound that's generated following the initial attack decay.

Release

__________ relates to how quickly the sound will decay once the note is released.

Decay

___________ refers to how quickly the sound levels off to a sustain level after the initial attack peak.

Acoustics

____________ is "a science dealing with the production, effects and transmission of sound waves; the transmission of sound waves through various mediums, including reflection, refraction, diffraction, absorption and interference; the characteristics of auditoriums, theaters, and studios, as well as their designs.

Masking

____________ is the phenomenon by which loud signals prevent the ear from hearing softer sounds and when the frequency of two sounds are close to each other.

Acoustic Isolation

____________ prevents external noises from transmitting into the studio environment.

Attack

____________ refers to the time taken for a sound to build up to its full volume when a note is initially sounded.

Complex Waves

____________, created by any naturally occurring sound (such as music or speech) are rarely repetitive in nature, are often not symmetrical about the zero line, and can be mathematically broken down into a series of ever-changing combination of individual sine waves.

Condenser

______________ mics operate on an electrostatic principle rather than the electromagnetic principle used by a dynamic or ribbon mic.

Iso Rooms

________________ are acoustically isolated or sealed areas that are built into a studio or just off the control room.

Iso Booths

________________ provide the same isolation but are often much smaller (usually called vocal booths).

Convolution

________________ result when two loud tones differ by more than 50 Hz.

Diffusers

_________________ are acoustical boundaries that reflect the sound wave back at various angles that are wider than the original incident angle.

Flutter Echo

_________________ is a condition that occurs when parallel boundaries are spaced far enough apart that the listener is able to discern a number of discreet echoes ("boingy").

Oversampling

__________________ increases the effective sample rate by factors ranging between 12 and 128 times the original rate by taking multiple samples of a single sample-and-hold analog voltage, lowering noise, increasing conversion quality, and making digital systems cost effective.

Imaging

____________________ is the ability to discriminate placement and balance in a stereo or surround field.

Transient Response

____________________ is the measure of how quickly a mic's diaphragm will react when it is hit by an acoustic wavefront.

Phantom Power

____________________ works by supplying a positive DC supply voltage of +48 V through both audio conductors of a balanced mic line to the condenser capsule and preamp.

Proximity Effect

_____________________ causes an increase in bass response whenever a directional mic is brought within 1 foot of the sound source.

Error Correction

_____________________ uses redundancy in the form of parity bits and check codes, or deliberately scattered patterns of bits in order to retrieve and or reconstruct lost data.

Bit Depth

______________________ represents the amplitude component of the digital sampling process.

Greater Word Length

______________________________ will often directly translate into an increased resolution (and, within reason, arguably higher quality) due to the added number of finite steps into which a signal can be digitally encoded.