Fundamentals of Audio Engineering and Signal Processing

Range of human hearing

20-20kHz (20,000 Hz)

Attenuation

Reducing the flow of the signal, turning down the voltage/loudness.

EQ/Equalization

We can attenuate bands (aka ranges) of frequencies with EQ and also boost bands of frequencies.

Primary wave forms

We have 4 primary wave forms: Sine (analog), Square (digital), Triangle, Saw (sawtooth, ramp).

AD Converter

Converts analog signals to digital signals, can be found in the audio interface.

DA Converter

Converts digital to analog so that we can hear it (through monitors).

Monitors

Boxes on top of the mixer that produce sound.

Sampling rate

The number of times per second that the computer takes a 'picture' of the audio, or samples the incoming audio.

Common sampling rate

44,100 Hz (44,100 times per second) for audio and 48kHz for film.

Bit depth

Regards amplitude, with common bit depths of 16 and 24.

Recommended bit depth

24 bit, 44.1/48.

Types of EQ filters/shapes

6 types: Low cut/High Pass, High cut/Low Pass, Notch filter, Peak filter, High shelf, Low shelf.

Low cut/High Pass filter

Makes sound thin and brittle, cutting the lows.

High cut/Low Pass filter

Makes a sound muffled, cutting the highs.

Notch filter

Can be used to attenuate a narrow band of frequencies, cuts out one little bump.

Peak filter

Can be used to boost a narrow band of frequencies, bring up a bump.

High shelf filter

Boost or attenuate a range of high frequencies without cutting them.

Low shelf filter

Boost or attenuate a range of low frequencies without cutting them.

Cutoff frequency

With a low or high pass filter, at some point, the attenuation begins creating a sloped line.

Types of microphones

Two types: Condenser and Dynamic.

Condenser microphone

Requires phantom power (48 volts), very fragile, operates on electrostatic principle.

Dynamic microphone

Plug it in and go, does not require any extra power source, not fragile.

Ribbon mic

Super fragile.

Fader

Bottom of mixing desk for volume attenuation.

Microphone cables

XLR (External line return).

Limiter

End of signal chain in mixing/mastering, recommended output level: -1.0 LUFS or DBFS.

LUFS

Loudness Units relative to Full Scale, based on human perception.

Frequency response chart

Every microphone is more or less sensitive to different frequencies.