Audio (1. & 2. Sem | 2024) Flashcards
What’s the Human hearing boundaries: frequency range (in Hz) and dynamic range (in dB SPL)?
The limits of our hearing range in terms of frequency: (20 – 20 000 Hz) and dynamic range (0 – 137,5 dB SPL)
How many dB correspond to “double sound pressure level”?
+6 dB
How many dB correspond to “double sound power or intensity”?
+3 dB
How many dB roughly correspond to “double perceived loudness”?
in the middle frequency range, about 250-2500 Hz, +10 dB
How much more power in W is required to get +10 dB SPL?
10 times the power in W
Equal Loudness Contour curves (ISO 226:2003). What do they show?
That our perception of loudness is not “linear” and depends on both the frequency and the dynamic range
Reference level (in dB) for electrical audio signals, consumer standard?
-10 dBV
Reference level (in dB) for electrical audio signals, professional standard?
+4 dBu
Reference level (in dB) for digital audio signals?
0 dB FS
Digital audio: relation between quantizing precision in bits and dynamic range?
Each bit ads about 6 dB dynamic range
Characteristics of Omnidirectional Microphone
- Omnidirectional – pure pressure transducer.
- the same sensitivity from sound coming from all directions
- very flat response across the complete frequency spectrum
Characteristics of Wide Cardioid or sub-cardioid Microphones
- cross between Omnidirectional (Omni) and Unidirectional (Cardioid) patterns, with mild directivity.
- to record instrumental groups in an orchestra, but without focusing too much on a single instrument
Charactersistics of cardioid Microhones
- Unidirectional, with pronounced directivity.
- This polar pattern has maximum sensitivity on-axis (0°), -6 dB from the sides (90° and 270°) and minimum sensitivity from the rear (180°).
- Standard close-up support microphone
Charactersistics of super-cardioid & hyper-cardioid Microhones
- cross between cardioid and bidirectional
- directional sensitivity than the cardioid
- the rear-lobe response is out-of-phase.
Charactersistics of shotgun Microhones
- cross between cardioid and bidirectional
- extreme directivity.
- example: to interview somebody in the middle of a noisy crowd
Charactersistics of figure of eight Microhones
- Bidirectional pattern – pure pressure gradient transducer.
- 2 two symmetrical sensitivity lobes, with maximum sensitivity on-axis (0°) and from the rear (180°); minimum sensitivity from the sides (90° and 270°).
- the rear-lobe is out-of-phase
Which microphone type has the best frequency response?
Condensor (best), ribbon (good)
Which microphone type has the most accurate transients??
Condensor (best), ribbon (good)
Which microphone type has the lowest self noise (S/N ratio)?
Condensor Microphone
Which microphone type has the highest sensitivity?
Condensor (best), dynamic (good), ribbon (bad)
Which microphone type has the highest headroom?
Dynamic Microphone
Which microphone type is best for live usage?
Dynamic Microphone
Which microphone types required phantom power?
- Dynamic (NO phantom power or batteries)
- Condensor (49V phantom power)
- Ribbon (NO phantom power)
Live amplification of vocals in a rock concert: what microphone would be the best choice?
(Between a dynamic cardioid, a condenser omni, a ribbon figure-of-eight and a PZM)
cardioid Dynamic
Live amplification of a drum kit in a rock concert: what microphones would you choose as
overheads? (Think about the requirements for impulse accuracy and high-frequency range
transparency …)
Condenser, because of accuracy in transient response and linear response in high frequency range
Dynamic only for the bass drum, since they have higher headroom
In which context can the “proximity effect” occur? (Think about the microphone type, polar
characteristic and distance from the sound source)
The “Proximity Effect” is an undesired boost of the lower frequencies that occurs when a microphone with directional polar pattern is placed very close to the sound source
In which context can “comb filtering” occur? (Think about multiple microphone sources, or
reflective surfaces in proximity of the sound source and microphone)
The interference from the direct and delayed sound wave causes a type of phase interference called “comb filtering”
What are the two basic principles used in stereo recording setups? (ITD and IAD)
ITD based on differences in time delay between the L and R channel, that are caused by the incident of sound waves when reaching the two microphones with time delays at different angles.
The IAD based on differences in amplitude (peak, level) between the L and R channel, that are caused by the varying sensitivity of the cardioid polar pattern at different incident angles.
Equalizers: In which situation would you choose a shelving EQ, a peak EQ or a hi/low cut filter?
SHELVING EQ general tone correction, to adjust the balance of the low and high frequency range. If an instrument just sounds too dark and muddy, or too thin and harsh
Peak EQ is used for accurate tone shaping, to remove or emphasize specific formants, to change the character of a sound, etc.
Low-Cut to eliminate low frequency noise or vibrations. For mechanical noise transmitted through the floor to the microphone stand, or traffic noise.
High-Cut Filter on bass range instruments to remove high frequency noise (hiss); it can be used to soften an otherwise aggressive instrument or special effect in dance and electronica styles
Dynamic effects: what is the purpose of a Compressor, a De-Esser, a Limiter and an Expander/Gate?
Compressor: reduces the level of the signal by a set ratio, once the signal level crosses beyond a defined threshold.
Limiter: works with a hard-knee curve, infinite compression ratio and very fast attack and release times.
De-Esser: reacts only to the frequencies in the specific range of “S”, “T” and other consonants (usually, a range between 5 to 10 kHz).
Expander/Gate: remove undesired, low dynamic level parts of a signal or to reduce/remove noise between vocal parts.
What effects can be used to add movement and dynamic changes in color (modulation) to an
instrument track?
chorus, flanger, phaser
What effects can be used to add space and depth to an instrument or vocal track?
delay, reverb
Which effect categories are generally used as send/return?
delay, reverbs
Which effect categories are generally used as insert?
EQ, filters, dynamics, distortion
Which effect categories can be used both as insert or send/return?
modulation effects and Distortion
Which notation type defines the exact pitch of the notes, but not their exact duration?
Square notation on 4-lines
Which are the most used metrical feet in musical context?
iamb, trochee, dactyl, anapest
How many lines does a standard modern notation staff (or stave) have?
5
What is the difference between beat, time signature and tempo?
Beat: The grouping of the underlying pulse of a Rhythm, Basic unit of time
Time Signature: how many beats in there are in each bar/measure
Rhythms: arranged with respect to a time signature, partially signifying a meter
Meter: organization of music into regularly recurring measures or bars of stressed and unstressed beats.
Tempo: how quickly the beat flows in bpm
In which tempo signature are these musical styles written in: Jig, Tarantella; Polka, March; Waltz,
Minuet; Pop/Rock, Techno, Trance?
4/4 = rock, blues, country, funk, and pop; allemande, bourrée.
2/2 = marches and fast orchestral music; gavotte
2/4 = polkas or marches
3/4 =waltzes, minuets, scherzi; sarabande; country & western ballads, sometimes used in pop
6/8 = double jigs, polkas, fast obscure waltzes, tarantella, marches, barcarolles, loures, and some rock music.
12/8 = baroque gigue (jig); common in slower blues and doo-wop, rock music.
In standard pop/rock/dance music written in 4/4, where is the snare drum usually placed?
2nd and 4th beat
The bass drum is typically used as a …
down beat instrument, 1st and 3rd
The snare drum is typically used as an …
up-beat or off-beat instrument, 2nd and 4th
What is a “drumbeat” or “drum pattern”?
A rhythmic pattern establishing the meter and groove through the pulse and subdivision, often defining specific music genre. Played on drum kits and other percussion instruments.
Which genres are “off-beat”?
Jass and Blues
What is groove?
sense of swing, soul or other genre, playing laid back or shaker tambourine is slightly before, tension makes groove
What’s the relation between dynamic range and bits of quantizing precision?
Each bit adds about 6 dB of
dynamic range / signal-to-noise ratio. CD=16 bit 44.1 kHz= 96 dB. 24 bit = 144 bB
What’s the difference between dynamic range of a digital audio format and dynamic range of a recording?
4-bit: dynamic range of 144 dB digitally, but dynamic range achievable in a recording 110-120 dB.
What are the different dB units and scales?
- SPL: sound pressure level of sound transmitted in an elastic Medium
- dBu and dBV: electrical audio signals, dBu = 0 dBu = 775mV, dBV = 0 dBV = 1 Volt.
- dBFS: digital Signals
- Standards: +4 dBu for professional audio and -10 dBV for consumer standard.
What’s the relation between sampling frequency and audio bandwidth?
The sampling frequency must be at
least double the required bandwidth (Nyquist theorem). The available bandwidth is therefore ½
the sampling frequency.
A sampling frequency of 44,1 kHz (CD Standard) allows roughly 22 kHz of audio bandwidth; however, the frequency response is only linear up to 20 kHz.
What’s Digital clipping?
Signals beyond 0 dBFS causes heavy distortion. Internally clipping can be avoided using a 32-bit float capable audio engine
What’s Aliasing?
If signal components that are above the Nyquist frequency enter the audio to digital
converter without proper “anti-aliasing filtering” they get “mirrored” around the Nyquist
frequency itself, appearing back into the hearable freq. range
What’s Quantization Noise?
At the lowest boundaries of the available dynamic range, rounding errors caused by insufficient accuracy in the measurement of each sample becomes digital noise
What are example Audio driver models (multitrack input output and low latency)?
ASIO and CoreAudio
What are the Loudness Measurements and Standards?
- Basic unit: LUFS or LKFS
- LUFS and LKFS are identical, and both use a gate and roughly corresponds to 1 dB.
- Integrated (I), Short Term (S) and Momentary (M) loudness values:
- Integrated LUFS: measurement from the start to the end of the track
- Short Term LUFS: the last 3 seconds of audio
- Momentary LUFS: the last 400 ms of audio
- Streaming platforms: what are the target loudness levels adopted by streaming services?
Spotify, Yt, Amazon Music (-14 LUFS), Apple Music (-16 LUFS) - Broadcasting: what is the target loudness level adopted by most European TV broadcasting
stations? (-23 LUFS, max True Peak -1 dB)
What are the advantages/disadvantages of digital plugins vs. analog effect processors?
interface, price, number of instances, settings and presets, parameter visualization, etc.
What are plugin standards?
VST, AU, AAX
What is the difference between native and DSP plugins?
Native plugins: CPU, DSP plugins require an internal DSP card or external DSP expansion
Which effect groups are generally used as insert, which as sends?
- Inserts: EQs, filters only work on 1 track or group they are inserted in.
- Sent/return: Reverb, echo, delay, multiple tracks.
- both: Modulation and distortion effects
What are High Shelving and Low Shelving filters (EQ and Filters)?
general correction of the bass/treble balance
What are Full Parametric Peak (or Bell) filters (EQ and Filters)?
detailed sound design (gain, frequency, bandwidth
What are High-Cut/Low-Cut filters (EQ and Filters)?
remove the frequency range below or above the cutoff
What’s A Notch Filter (EQ and Filters)?
remove a single disturbing frequency
What are EQ Parameters (EQ and Filters) ?
Gain, frequency, bandwidth
Whats’s a compressors (Dynamic Effects)?
reduces dynamic range
What’s a Limiter (Dynamic Effects)?
avoid “clipping”
What’s a De-Esser (Dynamic Effects)?
reduce “s” and “t” or hi-hat
What’s an Expander/Gate (Dynamic Effects)?
reduce “leaking” between the instruments of a drum-kit, reducing the level of audio signals once they drop below a defined threshold.
What’s a Multiband Compressor (Dynamic Effects)?
affect just specific instruments in a mix, or part of the frequency range in an instrument
What’s a Transient Designer (Dynamic Effects) ?
changes shape of percussives
What’s a Threshold (compression parameter)?
in dB the level beyond which compression occurs
What’s a compression ratio (compression parameter)?
relative to input dB vs output dB level changes
What’s soft/hard knee (compression parameter)?
when compression occurs, gradually or with increasing ratio
What’s make-up gain (compression parameter)?
in dB, compensates for the loss of gain caused by the compression
In which unit is attack, hold and release time measured (compression parameter)?
in ms
What is a mix (compression parameter)?
balance of dry signal vs. compressed signal
What are Delay and reverb effects for?
to add space and depth to a mix
What’s an echo/delay?
creates discrete repetitions of the original signal
What’s a reverb?
pattern of reflections
What are the 2 types of reverbs?
- impulse response reverbs (very authentic, but only a few parameters can be
adjusted. They are mainly used for classical and acoustic mixes.) - algorithmic reverbs (detailed adjustment of every Parameter, used for pop/rock/electronica mixes)
What are the different types of delay?
mono, stereo, ping-pong, tape delay
Which are the Reverb parameters?
room type, size, reverb time, pre-delay, diffusion, modulation/chorus, mix
Which are the Delay parameters?
Delay time, feedback (number of repetitions), hi/low cut filters, mix, stereo width
What are modulation effects?
one or more delay lines, modulated in pitch by an LFO
What’s chorus?
longer delay times (10-100 ms), best with percussives
What’s a flanger?
shorter delay times (0.1 – 10 ms), good with guitars, keyboards
What’s a phaser?
does not really use a delay, but rather “all pass filters” that just alter the phase of the signal, also causing coloration when combined with the original (dry) signal due to comb filtering, good on percussives
What’s the Leslie (rotary speaker)?
a sort of “analogue modulation” effect realized with a special
speaker cabinet that features a rotating woofer (= bass) and rotating tweeter (= treble) with independent speed controls. Used with the “Hammond” organ
What can you do in a multi-track recording to avoid comb filtering (remember the example where we found out we need about 18 dB of difference between two identical, delayed signals to avoid comb-filtering)?
- choose an instrument and microphone with enough distance between sources and microphones
- use different microphone orientations (cardioid bc of -6 dB from the side)
The stereo recording configurations differ what these aspects?
- Stereo Image Width: can be wide or narrow
- Correlation: the L-R signals can be more or less phase-correlated
How is the A-B setup (ITD only)?
- two omnidirectional microphones, spaced about 40-80 cm; it sounds very wide, but also quite diffuse and offers poor localization; the L-R signals are not correlated = no mono
How are the X-Y and M/S set ups (IAD only)?
- X-Y uses two cardioid microphones, with no spacing but 90° angle; It sounds very narrow, but
has precise localization; the L-R signals are correlated = mono - M/S uses a cardioid and a figure-of-eight microphones, with no spacing; it can sound narrower or wider, good localization, mono compatible.
What are characteristics of ORTF, NOS and OSS?
They are a combination of ITD and IAD, good, stereo width, good localization but are not perfectly mono compatible, to record an orchestra
- ORTF uses two cardioid microphones, spaced 17 cm and with a 110° angle, spacing same as our ears
- NOS uses two cardioid microphones, spaced 25-30 cm and with a 60-90° angle, for instruments placed in the middle of the stereo image.
- OSS uses two omnidirectional microphones, spaced 17 cm and with a “Jecklin Disc” as separation to achieve IAD in combination with ITD, sounds “roomier” than ORTF or NOS and it has the flattest frequency response.
Characteristics of Balanced Audio Connections?
- allows the use of long cables without the risk of external noise or interference
- use shielded twisted-pair cable and three-conductor connectors
- difference between XLR (balanced), TRS jack (balanced), mono jack (unbalanced) and RCA (cinch, unbalanced) connectors.
What are the two extreme principles used in composition?
- unrelieved alteration (boring)
- unrelieved repetition (annoying)
What’s the difference between motif and riff?
motif: melody
riff: mainly rhythm/pattern
How are themes and variations “patterned”?
In As (A A1 A2 A3 A4 A5)
What’s a Rondo pattern (Themes and variations)?
(A B A C A D A …)
What’s a Menuet pattern (Themes and variations)?
larger ternary form A B A’; each section is binary: A [a a b b] B [c c d d] A’ [a b]
What’s a contemporaray Song pattern
(Themes and variations)?
A1 A2 B A3 A4 B B
What’s a Sonata Form?
Exposition (first subject group, transition, second subject group, closing group), Development, Recapitulation, Coda
Other example Themes and variations?
Fugue, Canon, Medley / Potpourri
Notes, Intervals, Scales in western music?
(A B C D E F G = do re mi fa sol la si)
What do the 5 black keys mean?
“♯” (sharp = a half-tone higher) or “♭” (flat = a half-tone lower)
What is a half tone?
no in-betweens E-F, B-C, F-F♯ and B♭-B
What is a tone?
tone is 2 half-tone steps key in-between C-D, E-F♯, G-A, B♭-C
What’s an octave?
includes a total of 12 half-tone steps
What are intervals?
they are counted including the start and the end note (unison, second, third, fourth, fifth, sixth, seventh, octave, ninth)
What’s the tone/half-tone sequence of a major scale?
T-T-HT-T-T-T-HT
The matrix is “C-Major” C D E F G A B (C) , how is it transposed to F-Major?
F G A B♭ C D E (F)
What’s the tone/half-tone sequence of a natural minor scale?
T-HT-T-T-HT-T-T
The matrix is “A-minor”: A B C D E F G (A), how is it transposed to D-minor?
D E F G A B♭ C (D)
From a tonality point of view, what are the main steps of a scale?
- the Tonica (1. step), the center of gravity of a tonality
- the Subdominant (4. step), one fifth (Quinte) down from the Tonica, can prepare the Dominant chord
- the Dominant (5. step), one fifth up from the Tonica, usually resolves back on the tonica
In C-Major that would be:
- 1. Tonica = C
- 4. Subdominant = F
- 5. Dominant = G
Also important: the Mediant (3. Step), defines if a scale is major or minor
if you start from A-minor, the relative major is C-Major
- the Submediant (6. Step). The Submediant of a major scale is the start of the relative minor
if you start from C-Major, the relative minor is A-minor
What’s a perfect cadence?
“dominant -> tonica”
C-Major=-Major chord + C-Major chord
What’s a plagal cadence?
“sub-dominant -> tonica”
C Major= F-Major chord + C-Major
What’s a deceptive cadence?
“dominant -> (any other chord, but the tonic)”
usually “dominant -> submediant (Tonikaparallele) ”
C-Major = G-Major chord + A-minor chord
