Sound & Hearing Flashcards
Control Room
Where majority of engineer’s tools are kept
e.g. console, control surface, outboard gear, power amps, computer systems, multitrack machines, etc1
How is the Control Room built?
To be acoustically isolated from other parts of the studio (tracking rooms), including outside surroundings
What is the Control Room for?
Critical listening
What are the Two Recording Processes?
Real-time & Multitracking
What is Real-time recording?
With 1 or 2 mics, the musicians & artists would be positioned and play all together, recording live on one track - mixing is done at the same time
What is Multi-track recording?
All artists & musicians can be recorded on their own track, either at the same time or separate times, or even both - this allows endless mixing possibilities
What are the steps of pre-production?
- budget
- type of artist
- how many songs
- how many tracks for each song
- what format being recorded to
- how much studio time has been booked
- what is the goal of the project
3 Main steps to Recording
- Recording (tracking, basic tracks)
- Overdubbing - basic tracks are played over headphones and additional tracks are recorded to either fix, add, re-record an entire take
- Mixing (mixdown) - panning, balancing levels, eq, dynamic processing, time-based effects, etc
What is the definition of engineering?
The application of scientific & mathematical principles to achieve an end result
Transducer
Any device that changes one form of energy into another CORRESPONDING form of energy
Examples of Transducer
Microphones, speakers, guitar pick-ups, OUR EARS
3 Electrical levels & their measurements
- Mic level - millivolts
- Line level - 1.23 volts
- Speaker level - 1-50 volts
Subjective sound v. Objective sound
Subjective sound implies that a brain is required for sound
- Objective sound asserts that just because a brain may not be present, sound waves were still made, therefore, there is sound
Subjective sound
Brain’s perception & interpretation of vibration of a physical stimulus causing sound pressure waves to propagate through air
Objective sound
Repetitive vibrations of a physical object will produce variations in barometric/atmospheric pressure, aka sound pressure waves
What causes sound pressure waves?
Compression and rarefaction
Compression
Greater than normal atmospheric pressure
Rarefaction
Less than normal atmospheric pressure
List the 7 waveform characteristics
- Wavelength
- Amplitude
- Velocity
- Envelope
- Frequency
- Phase
- Harmonic Content
What direction do low frequencies travel in?
Omnidirectional
What direction do high frequencies travel in?
Unidirectional
Wavelength
The actual physical distance between the beginning and end of a cycle
Complex
Waves that are not necessarily symmetrical and don’t necessarily repeat
Waveform
A graphic representation of a signal’s sound pressure level or voltage level over time
Phase Shift
The difference in time between two waveforms
Amplitude
The distance above or below the centerline of a waveform
Producer
The person who helps the artist and/or record label create the best possible recorded performance and final product, and is also in charge of the entire session
Propagation
The process of sound pressure waves “travelling” through the air
Phase
A time relationship between two or more waveforms
Engineer
This person’s job is to interpret and capture the sonic and creative vision of the producer, artist, and record label through a recording and/or mix
Decibel (dB)
The unit of measurement for sound pressure level (SPL), voltage level, etc.
Fundamental
The note being played
Assistant Engineer
This person’s job is to run the tape machine, Pro Tools, setup and tear down session, document the session, and make sure the session runs smoothly
Peak-to-peak value
Distance from max positive value to max negative value
Peak-Amplitude value
Distance from centerline to max positive, or centerline to max negative
RMS (root-mean-square)
Average of all peak-amp values
Frequency
The measurement of the number of cycles that occur in one second of time/ cycles per second; unit is Hz
Variations in atmospheric pressure
Sound pressure waves
Sine wave
Simple wave; pure tone
Omnidirectional frequencies
Low frequencies
Unidirectional frequencies
High frequencies
Average range of human hearing
20Hz - 20kHz
Range of frequencies humans hear best
1kHz - 4kHz
Formula for Wavelength
W=Velocity / Frequency
Wavelength is measured in __________
Feet per cycle
What is the velocity of a sound wave at room temperature (70°F)?
1130 feet per second
1.1 feet per second
Velocity increases by this much for each degree increase, or decreases by this much for each degree decrease
Amplify
Increase in amplitude
Attenuate
Decrease in amplitude
Cycle
The completion of a wave 360°
Amplitude measurement
Decibels (dB)
Period
The time it takes to complete one cycle
The absolute positive and negative values in a wave form
Polarity
Envelope
The attack, decay, sustain, and release of a waveform
Fundamental
The frequency of the note being played
Harmonics
Whole-number multiples of the fundamental
When the frequency is doubled, that harmonic is called:
An octave
Sound reflects off a surface boundary at an angle _____ & ______ to its original angle of incidence
Equal and opposite
Diffraction
Sound pressure wave’s ability to “bend” around an object
Floating scale (dB)
Designed to measure one value against another
The best dB SPL for listening?
85dBSPL
Masking
When loud sounds cover up softer sounds, so we can’t hear them
Bell Labs engineers who established the Equal Loudness Contours of the human ear
Fletcher and Munson
How would you find the 3rd harmonic of 250Hz?
Multiply 750Hz by 3
How would you find the 1st octave of 500Hz?
Multiply 500Hz by 2
How would you find the 2nd harmonic of 1500Hz?
Multiply 1500Hz by 2
How would you find the 2nd octave of 200Hz?
Multiply 200Hz by 4 (200x2=400 (1st octave) then 400x2=800Hz (2nd octave))
Wavelength of a 1000Hz wave?
1130 feet/sec(velocity)/1000Hz cycles/sec(frequency)= 1.13 feet/cycle
Wavelength of a 20Hz wave?
1130 feet/sec(velocity)/20Hz cycles/sec(frequency)= 56.5 feet/cycle
List 4 things that could be done during mixdown?
- Combine tracks
- Balance levels
- Panning
- EQ & dynamic and time-based processing
Nominal level
The best operating for audio devices
What is nominal level in dB?
0dB
Area between nominal level and distortion
Headroom
Ratio of wanted signal and the noise floor
Signal to noise ratio
Crosstalk
Unwanted leakage between channels on a console or tracks on an analog tape
4 possible console inputs
- Mic
- Line
- Tape/Monitor
- Group Signal on the I/O
What are the 2 paths of a console?
- Channel path
2. Monitor path
2 types of console layouts?
- In-line
2. Split Monitor
MTR must be in ______ to receive signal & in ______ to record signal
Input & record ready
2 common ways to send signal to MTR?
Multitrack Bus (MTB) & Direct Out
Buss
A common signal line
Which fader sends signal to the MTR?
Source fader
Which fader receives signal from the MTR?
Return fader
Which fader receives signal from a MTB?
Group fader
Patchbay
The central location for all the audio wiring in a control room and studio
Mult
A passive bus that allows us to make multiple copies of an audio signal in parallel on a patchbay
Half-normal
Breaks at the input
Full-normal
Breaks at the input and output
Signal flow: Microphone leads to
Mic pre
Signal flow: Mic pre leads to
Source fader
Signal flow: Source fader leads to
Track pan
Signal flow: Track pan leads to
MTB
Signal flow: MTB leads to
Group fader
Signal flow: Group fader leads to
MTR
Channel path consists of:
Mic Pre, Source fader, Track pan
Direct Out jumps from _____ to ______
Source fader to MTR
Signal flow: MTR leads to
Monitor path input
Signal flow: Monitor path input leads to
Return fader
Signal flow: Return fader leads to
Stereo pan
Monitor path consists of:
Monitor path input, Return fader, Stereo pan
Signal flow: Stereo pan leads to
SB (stereo bus)
Signal flow: SB leads to
Master fader
Signal flow: MDR leads to
Control Room level
Signal flow: Control Room level leads to
Power amps
Signal flow: Power amps lead to
Speakers
2 types of Dynamic microphones
- Moving coil
2. Ribbon
Dynamic microphones operate by using ______
Electromagnetic induction
Condenser microphones operate by using ______
Electrostatic principle
ICA
Impedance Conversion Amplifier
What does an ICA do?
It lowers output impedance of the mic, and amplifies output voltage to mic level
PAD
Pre-attenuation device
What does PAD increase?
The mic’s max SPL
3 types of ribbon microphones?
- Passive
- Active
- Tube
Does the ICA require power?
Yes
What powers the ICA?
+48vDC (phantom power)
Should you send phantom power to a tube mic? Why?
No, tube mics have their own power supply
Pressure operated
Technical term for omnidirectional
Proximity effect
An increase in bass response as a directional mic is brought closer to the sound source
Transient response
Measure of how quickly a microphone’s diaphragm will react to an acoustic waveform
Rumble
3Hz - 25Hz frequencies that are transmitted through a building’s structure to the mic, causing unwanted noise floor
3 types of unidirectional polar patterns
- Cardioid
- Supercardioid
- Hypercardioid
Figure 8
Bidirectional polar pattern
Null point
The area where a microphone rejects the most amount of sound
On-Axis
The point where a microphone picks up the most amount of sound?
Matched pair
A pair of mics tested by the manufacturer to be exactly the same
Which type of mic has the fastest and most accurate transient response?
Condenser mics
High pass filter / roll off
Attenuates low frequencies entering the mic
Things to employ to help dismiss Rumble
- Roll off / High pass filter
2. Shockmount
Front address
The capsule inside the mic that captures sound pressure waves is facing upward
e.g. typical handheld dynamic mic
Side address
The capsule inside the mic that captures sound pressure waves is facing sideward
e.g. typical condenser mic (yours)
3 sections of the recording console
- Input
- Output
- Monitor
In a Direct Out signal flow: Source fader leads to
MTR
Decibel uses a ______ scale
Logarithmic
dBSPL
Decibels referenced to Sound Pressure Level
0dBSPL
The softest sound a human can hear
dBu/dBv
Decibels referenced to 0.775 volt
0dBu
0.775 volts
dBFS
Decibels referenced to Full Scale (digital)
0dBFS
CLIPPING
dBVU
Decibels referenced to Volume Units (analog)
0dBVU
Nominal level in analog
Attack
The time taken for the amplitude to build up to it’s max peak
Decay
The initial decline after the attack
Sustain
Changes in amplitude as the note is held out
Release
The final bit of sound produced as the note is finished being played
Frequency determines ______
Pitch
Velocity
Speed of sound
Harmonic Content
Tone/timbre of the fundamental frequency
Normals
Something pre-wired/connected to each other
Timbre
A component of harmonic content that allows a C played on a piano to sound different than a C played on a guitar
What kinds of power can a condenser microphone use?
+48vDC, external power supply, battery power
What makes up a capsule?
Diaphragm and back plate
In condenser microphones, what does +48vDC power?
The capsule and the ICA
FET
Field Effect Transistor
What kind of condenser mic wouldn’t need phantom power?
Tube: A condenser that uses a vacuum tube instead of a FET
Voice coil
The copper wire that is the moving coil in dynamic microphone
Mylar is part of what?
Diaphragm
Between the diaphragm and the back plate, which is fixed and which is moveable?
Diaphragm - moveable; Back plate - fixed
By default, dynamic ribbon mic are which directional?
Bidirectional
Pressure-gradient microphones
Directional microphones; they respond differently depending on where sound pressure waves come from
Signal flow: Master fader leads to
MDR
