Audio Recording and Production Principles

Notes Taken 1/22/14
Acoustic Decibel in Sound Pressure Language
0Db(spl) – silence
50dB (spl) – Whisper
100dB (spl) – Rock Concert
140dB (spl) – Threshold for pain
Note – the human body has a protection for instantaneous sounds above 140dB(spl) in the form of a tiny flapper, however this flapper muscle can wear out over time so it is important to protect your hearing
U stands for Unity, with U = 0dB (spl) – this is commonly found on mixers
As long as input level = outpul level, setting is said to be Unity
Mixers are often set in 10’s, so 10dB added is 2x as loud, and -10dB added is ½x as loud
Full Scale or FS = 0dB = unity on a digital mixer
A weighted or B Weighted deals with psychoacoustics and refers to how relatively loud the sound is to you
Phase
Phase Cancellation occurs when peaks and troughs between sound sources cancel eachother out because the speaker coil cannot push and pull at the same time
Absolute cancellation is called 180 degrees out of phase
By playing with phase, we can manipulate
Echo – long reflections that can be discerned as separate events
Reverb – quick reflections measured in milliseconds, reverb is known to “warm” audio and place it in actual space
Resonance – vibrations at resonant frequencies below or above root frequency
Sympathetic resonance – materials can resonate with resonant frequencies
Fletcher Munson Curve

Fletcher and Muson created a frequency response graph for the human ear
Basically, signals on high and low ends of spectrums must be boosted to be as relatively loud as midtones because our ears are attenuated to conversation frequencies
When all levels are increased, ear response flattens out (move graph up y axis and it would flatten)
The key is to mix and adjust for many different spaces and many different listening situations