Sound travels through air at 340 meters per second. The speed of sound affects how we perceive the location, depth, and space of sounds. Factors like temperature, humidity, and elevation can impact the speed of sound propagation. Audio delays and effects like reverb alter the perceived location of sounds by controlling delay time and feedback levels. Short delays under 5 milliseconds can produce pitch changes, while longer delays lower the perceived pitch. Reverbs create a sense of acoustic space and help focus the listener's attention. Convolution and algorithmic reverb use different methods to simulate real acoustic spaces digitally. Dynamic audio plugins like compressors, limiters, and gates control the amplitude of signals over time.

1. Sound basics
Propagation
Sound going through a medium Speed of sound in the air
340 meters/ sec
1 km/ 3 secs
1 mike / 5 secs
1ft / msec
Sense of
Space
Depth
Location
Affected by
Temperature
Humidity
Elevation
Audio effects that Control/ change propagation Delay effects
Delay time
Short
Long
Dry/wet
Dry= unprocessed Feels near
Wet= processed Feels far
Feedback
High feedback Delays continue for a long time
Low feedback Delays fade away quickly
The output if the delay unit
Is routed to the input
of the delay unit
The delay concept
Effects of delays
Pitch change
From ??? Upto 5 milliseconds Comb filters
A complex filter with a series
Of evenly spaced notches
When a signal is is combined
with a slightly delayed version of itself
Short delay + very high feedback
Increasing delay time
Lowers the frequency
of the pitch
Produces a pitch
Modulated short delays
Choruses
Flangers
Phasers
Reverbs
Sense of space
Guides listener's focus
Slap back
One wall short reflection
with zero feedback
Algorithmic
Creates impression of space form a formula
(synthetics)
Like a synthesizer
Doesn't sound like real space
More manipulation
Possible
Parameters
Early reflections Sounds like slap back
Diffused reverb
Under2 seconds
Material of walls
Convolution
A recording in real space applied to sound from
DAW (sampling)
More like real space
Limited manipulation
Like a sampler
Impulse response
Representation of sound
In real space
Canyon
Jazz club
Large hall
Etc...
Amplitude
Amount of compression of air
due to sound pressure
Longitudinal waves Same direction as wave propagation
Measured in decibels (Db)
Dbspl (Db sound pressure level)
In the air
Scale: 0 to loudest Zero is the quietest
Dbfs (Db full scale)
In the computer
Scale: Negative to zero Zero is the loudest
Not loudness
Perceived as loudness
Depends on
Duration
Frequency
Audio effects: Dynamic plugins
control amplitude of signal over time
Compressors
Limiters
Expanders
Noise Gates
Noise
Hum ,hiss ,fuzz
When signal isn't present
Acoustic Environment
Electrical Caused by Gear Reduce
Reduce pieces of gear
Shorter cables
Use balanced cables
Turn of appliances and dimmers
High quality gear
Mic polar pattern
Get mic closer to source
Distortion
Threshold of distortion
Amplitude at which volume starts affecting
timbre - volume variations turn into timbre
variations
Dynamic range Distance between noise flour and distortion
Drive
Gain stage before threshold of distortion
e.g guitar
Use distortion musically Intentional use of distortion
Gear can cause distortion
Non linear range of equipment
Mic Too close
Not good
Needs to be illuminated
Mic preamp Clipping (digital distortion)
Not good
Needs to be illuminated
Frequency
Timbre