3005 final exam

The ear is more sensitive to Mid-range frequencies than low and high frequencies at low volumes. As volume increases, the curve of our hearing flattens out so we hear all frequencies equally (around 85db). However, our ears become more sensitive to high and lows once volume increases past this point.

The height/ Vertical distance of a sound wave

The number of cycles of a sound wave completes in one second, perceived as pitch. It is measured in Hertz (Hz).

The travel of a soundwave

The lowest frequency of a given sound wave. It determines the pitch of that wave.

Higher frequencies above the fundamental that help create the timbre of a sound.

Overtones that are multiples of the fundamental frequency.

A sound envelope is the changes in amplitude (rise and fall of volume in a note.) Attack: The start or “trigger” of the sound. It is the increase in volume from silence to the loudest point of the sound. The speed of the attack will depend on the instrument and how it is played. Decay: The decrease in volume from the peak of the attack to the average level of the note. Sustain: The maintained volume of a note as it is played/ held Release: The decrease in volume from the average level to silence once the trigger is removed.

When two sound waves travel in phase with each other, causing an increase in amplitude/ volume

0 dB SPL

120 dB SPL

130 dB SPL

2 matched mics that are either Omni or cardioid mics placed on a sound source using the 3:1 rule.

Two cardioid mics placed together with their capsules touching, angled at 90 degrees. Because the capsules are touching, sound will reach them at the same time, thus eliminating phase issues.

Two Cardioid mics angled at 110 degrees, overlapping mid-body. Creates a wider stereo image than XY.

Two cardioid mics angled at 90 degrees overlapping at the base/ connector.

A cardioid mic is placed above a bidirectional mic, with their diaphragms angled at 90 degrees.

Two bidirectional mics stacked on top of each other, angled at 90 degrees. Picks up the Left and Right of the sound source.

Three matched omnidirectional mics placed in an equilateral triangle to cover a very large area. Commonly used for orchestral recordings.

Small omnidirectional Mics placed in the ears of a dummy head to replicate the stereo Image of what the human ears typically perceive in real life.

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32

Turn loud sounds down

The distance between the quietest and loudest sound of a signal. It’s the range of volumes a signal can hit while still being accurately represented.

The lowest point in a signal , where ambient noise builds up.

The amount of signal a piece of equipment allows before overloading. Similar to dynamic range.

The point the signal level has to pass to get compressed.

The Knee

Lower

No, it has an input control and set threshold.

The difference between the input and output. Ranges from 1:1 to 10:1. A higher ratio means a more dramatic change.

The time it takes for a compressor to react and reduce a signal when it passed the threshold.

How fast the compressor resets to its original position after it is engaged.

Medium Attack and medium Release

It will cut off the initial transient of the signal.

The output level of a compressor. It turns up the volume of the entire compressed signal.

Gain reduction meter. Reacts to incoming signal

Output meter for pro audio

Nothing is done to the signal until it passes the threshold at which point the compressor kicks in at the set ratio. This is the most common curve.

Compression is applied gradually as a signal approaches the threshold, increasing to the set ratio when the threshold is passed. It’s more musical and good for soft acoustic recordings.

It is slow and sluggish. Has less top end,creating a fat sound.

Field Effect Transistor. Has super fast attack and release capabilities

Optical circuit. Uses a photocell detector to determine gain reduction. A light glows according to the incoming signal. They are less sensitive to transients and have a slow/smooth sound.

A separate path of audio used as the control for a compressor

Using a side chain to allow the level of one signal to be controlled by the level of another .

An extreme version of a comrpressor that stops any signal from passing the threshold, preventing it from clipping. The ratio is anything above 10:1, usually 12:1 or 20:1

A device used to increase the dynamic range of a signal. Signals below the set threshold are turned down, while signal above the threshold is left unaffected

An extreme version of an expander. Signal below the threshold is completely cut out. Opposite of compressor

Attack = How fast the gate opens once the signal passes the threshold Release = How fast the gate closes after it opens

How much signal passes when the gate is closed. Completely muted (gate) vs. low signal (expander)

It maintains the sustain portion of the sound envelope, stopping the expander from releasing for a set amount of time.

Reverb is the reflections of a sound. Delay is the echo (past the point of reverb)

The material of the room. Hard surfaces are very reflective and emphasize high/bright frequencies. Soft surfaces are less reflective and emphasize low/warm frequencies.

Sound Waves that travel in a straight line from the source to the listener.

Sound waves that reach the listener after direct sound

1 millisecond of reflection is equal to a 1 foot distance in a real space.

The original trigger of a sound/ the highest amplitude of a sound.

Sound waves that bounce off of nearby surfaces and reach the listener within 30 milliseconds after the direct sound. They aren’t perceived as reverb, but give the listener a sense of the size of the space and add fullness to the sound.

Reverberation. Densely spaced reflections that have bounced off of many surfaces in many directions. They last longer and overlap, causing the brain to interpret them as a continuous stream of information. Occur around 50 Milliseconds after the initial impulse

Reverb Time. The time it takes for the volume of a sound to decay by 60dB from its original amplitude. Our ears use this to interpret the hardness/softness of the surrounding surfaces A long reverb time = Hard surfaces Short reverb time = Soft Surfaces

Reflections of a sound that become longer, and are perceived as distinct repetitions of that sound.

The direct sound is louder than the reverberations.

The reflections are louder than the direct sound.

Our perceived distance from the sound source.

One of the first types of artificial reverb. A loudspeaker is placed in a highly reflective room and plays a signal. One or two microphones in the room record the reflections, which are then mixed in with the original sound.

An analog reverb unit, where a signal is applied to one end of a spring through a transducer, causing vibrations. A transducer at the other end of the spring converts the motion into an electrical signal, which can then be mixed with the dry sound. The time it takes for the signal to travel through the spring coils creates the delay time.

A type of analog reverb similar to spring reverb. A metal plate is suspended in a frame, and a transducer applies a signal to one side of it. The reverberations of the plate are picked up by one or two transducers on the other side. The EMT 240 in Studio 1 is an example of this

Replicates the reverb of various types and sizes of spaces using complex computer algorithms. The Bricasti in Studio 1 is an example of this.

Determines how long late reflections last once the source signal stops. Might also be called reverb decay or RT60. Small rooms’ reverb length is usually between 0.5 - 1 second Medium Rooms ae 1 - 2.5 seconds Large rooms/halls/etc are greater than 2.5 seconds

Controls the “thickness” of the reverb. More diffusion pushes early reflections together, replicating a room with many irregular surfaces, creating a thicker sound. Less diffusion pushes early reflection apart.

The amount of time between the direct sound and first reflections. It creates a sense of distance between the sound source and the room. A longer pre-delay makes the sound source feel closer to the listener.

Tape echo, invented by Les Paul.

Automatic Double tracking. Takes a copy of the original track and plays it back with a 15-30 millisecond delay to imitate the effect of recording a double for a given part.

A delay effect where a copy of a signal is delayed by 20-30 milliseconds, then a portion of the delayed signal is fed back into the input of the delay. It gives the effect of having multiple ‘voices’ on a single part

A delay time of 50-100 milliseconds, heard as a single early reflection.

A delay with a delay time longer than 100 milliseconds. Creates a callback effect.

A stereo delay effect using separate delay units, whose outputs are hard planned in opposite directions. The original sound source is sent to the first delay, and a portion of the output of the delay is used at the input of the second delay unit, which has a longer delay time. Some of the output of the second delay is then sent back to be input into the first delay unit. This creates the effect of the sound source bouncing back and fourth between the two speakers.

A ‘swooshing’ effect created by mixing a signal with a very short delayed copy of itself. The delayed signal is fed back into itself, with the delay speed constantly changing. The changes in time cause the two signals to go in and out of phase with each other, cutting or boosting the signal and causing small changes in pitch.

When two copies of a signal are put in and out of phase with each other, creating a slight “wooshing” effects the signal is boosted/cancelled.

Controls the amount of times the signal is fed back into itself/ how many repeats are in the delay.

Our brain will interpret the original sound source and any reflections that occur less than 30 milliseconds after it as a single sound.

The prevention of unwanted sound from entering or escaping an environment.

An acoustic environment should not alter the sound quality of the original recorded performance.

A portion of the energy passses through the barrier, a portion is reflected off the barrier, and a portion is absorbed by the barrier.

When some of the energy of a soundwave is trapped within the material it hits. It mainly happens to high frequencies, with soft and porous materials being the most effective.

When a sound wave bounces off a surface at the same angle it struck it at.

When a sound wave strikes an irregular surface, reflecting off of it at different angles. It lowers the amplitude of the reflected waves and evenly spreads reverberant sounds throughout a room.

When a sound wave bends/spreads around a surface.

The frequency an object naturally vibrates at.

When air is pushed into volume of a cavity and then released at a high pressure level, the walls of the cavity will resonate at certain frequency. Empty cavities in construction have their own resonant frequency, which can get pushed back into a studio, altering our perception of the original sound source.

When two or more sound waves are in phase with each other, causing an increase in amplitude.

When there are two parallel walls, certain frequencies will be reinforced based on the distance between the walls. As sound waves reflect between the walls, these frequencies pile on top of each other through constructive interference, altering out perception of the original sound source.

A type of parallel wave occurs when a frequency’s wavelength is two times the distance between two parallel surfaces, causing buildup of that frequency between the surfaces.

Reflections of a frequency that reach the listener completely out of phase.

Unwanted sound within a recording or recording environment.

Airborne - ambient noise, traffic, HVAC Structure borne - Vibrations through floors, caused by mounted machinery shaking teh structure. Impact borne - Heavy rain/hail, footsteps

Below 25dB SPL

A type of diaphragmatic absorption used to control low frequencies. A cavity is built with a membrane or panel absorber covering it, that resonates in the same frequency as the problematic frequencies. When a sound wave strikes it, the panel will resonate at its designated frequency, dampening the sound wave in that frequency range through phase cancellation.

It’s a structure used to eliminate low frequency standing waves. Made up of an enclosed airspace with small openings attached to it. When a sound wave at or near the resonate frequency of teh resonator hits the surface, the air inside the openings is set into motion. The enclosed space resists the movement, forcing the vibrating air in the openings back out towards the soundwave. This causes a phase cancellation between the soundwave and the waves exiting the resonator.