Audio Fundamentals PDF

Aspects of Communication Audio  Hz Frequency Cycles per Second Measured in Hertz (Hz) Higher frequency = Higher pitch of the sound  As seen in the examples above 20 Hz = 20 repetitions per second 40 Hz = 40 repetitions per second 80 Hz = 80 repetitions...

Aspects of Communication Audio  Hz Frequency Cycles per Second Measured in Hertz (Hz) Higher frequency = Higher pitch of the sound  As seen in the examples above 20 Hz = 20 repetitions per second 40 Hz = 40 repetitions per second 80 Hz = 80 repetitions per second  Hz (Numbers to Know) Theoretical Range of Human Hearing 20Hz - 20,000Hz or 20KHz (Kilo Hertz) Sample Rates: Example CD Quality 44.1 KHz or 44,100Hz Just for Fun  Good to Know Human Voice Range = approx 80Hz-4000Hz (Fundamentals are lower - Males 80-180Hz, Females 165-255Hz) In this range human voice is intelligible (meaning, you can understand what is being said) Telephones usually have a sample rate of 8000Hz because of this factor. Their range is between 300 Hz-3400 Hz A sample rate is usually double (or more) of the range of sounds that are being recorded or rather targeted.  dB Decibels Used to measure the Amplitude of the sound wave Larger Amplitude = Louder Volume Dynamic Range is expressed in Decibels  dB (Numbers to Know) 0 dB - The Threshold of Human Hearing (we cannot hear anything under this) A 16 bit Recording has a Dynamic range of 96 dB A 24 bit Recording has a Dynamic Range of 144 dB Dynamic Range = The Difference Between the Lowest and the Highest sounds in the recording  Good to Know 120 = 140 dB = Threshold of Pain 140 dB = Maximum Theoretical Range of Human Hearing (In terms of Dynamic Range)  We also meet dB Gain staging when recording 0 dB = Unity Gain When Mixing our tracks Volume Fader Tracking means when we are recording audio either from a vocal source (microphone) or from instrument inputs Remember to make sure that when recording levels are kept around -12dB, and to adjust this from the gain knob on the interface/preamp  Gain ? Volume? Level? All these refer to Loudness Gain refers to the input signal or the loudness that our signal is being recorded at. This is controlled from either the interface or the preampli ers that our microphone/instrument is plugged into. Level refers to the loudness in our mixer, where our volume fader lies in relation to unity gain. This is controlled from our volume fader on the mixer or the DAW Volume typically refers to the output signal fi Equalisation  2 Main Types Parametric Graphic Freq = Frequency in Hz Gain = Boost + or Cut - in dB Q = Bandwidth (Higher Q = more precise control Lower Q = broader control) The Q typically refers to the centre frequency in a bell curve In this diagram f0 In graphic Equalisers the Q is usually preset  Equalisation works by controlling the amount of loudness of speci c frequencies We can Boost or make louder certain frequencies or we can Cut speci c frequencies to make them less audible We use equalisation to enhance or to correct our audio fi fi Compression In compression we control the Dynamic Range of our audio We use compression to reduce the distance between the loudest and the softest sounds in our track Threshold: When we want our Compressor to start working (in dB) The Ratio = How much compression we want to apply to our signal 1:1 means no compression 2:1 means for every 2dB above our Threshold only 1dB is output 4:1 means means for every 4dB above our Threshold only 1dB is output Hard Knee means that our compressor comes on hard once the threshold level is reached Soft Knee means that our compressor comes in more gradually Attack Time = How quickly our input signal starts being compressed once it goes above the threshold level Release Time = How quickly our input signal stops being compressed once the signal goes below the threshold level Both are measured in milliseconds (ms) Terms and Abbreviations DAW - Digital Audio Workstation MIDI Musical Instrument Digital Interface AD/DA (Converters) - Analog to Digital / Digital to Analog ADSR Attack Decay Sustain Release Recommended Channels