Audio Engineering Fundamentals

Explain how digital audio uses sample rate and bit depth, compare 44.1 kHz and 48 kHz, and 16 bit versus 24 bit, and advise recording at 24 bit.

Understand how analog sounds become digital data through sample points, and how software like Pro Tools connects data points to form waves before digital-to-analog playback.

The Nyquist theorem requires at least two samples per cycle to capture up to 20 kHz, needing 40 kHz sampling. 44.1 and 48 kHz suffice; higher rates risk aliasing.

Understand how sample rate and bit depth affect audio in Pro Tools. Converting a mismatched file (44.1 kHz 16-bit) to the session rate (48 kHz, 24-bit) preserves speed and pitch.

Explore how bit depth sets dynamic range in digital audio, from 16-bit 96 dB to 24-bit 144 dB, and learn how dither preserves quality when converting bit depths.

Discover how bit crushers lower bit depth to reduce dynamic range and produce lo-fi distortion. Learn how sample rate and anti-aliasing control high-frequency content and digital artifacts.

Visualize bit crushing on a snare with audio suite and Kilohearts. Lowering to two or three bits collapses dynamic range into few volume states, with noise reduced to silence.

Explore how fixed point bit depths, notably 16- and 24-bit, determine sample resolution, cause clipping at max values, and introduce quantization noise due to rounding, with higher 24-bit reducing noise.

Explore how 32-bit floating point preserves audio data when distorting a channel in ProTools, and contrast fixed point with floating point systems, including scaling by an eight-bit scalar.

Explains recording directly into 32-bit floating point, why most interfaces stay at 24-bit, and how 2019 hardware enables true floating-point capture for film and beyond.

Explore mic level signals, line level, and signal strength categories, and how a pre-amplifier boosts mic level to line level. Clarify why an xlr cable and xlr input nomenclature matters.

Learn how microphone preamps boost mic level signals to line level in analog audio paths. See how a channel strip combines mic preamp, eq, and compression in one unit.

Learn why mic level is much lower than line level and how line level signals drive tape machines, high-end analog-to-digital converters, and preamps that convert mic to line level.

Explore the professional +4 dBu and consumer -10 dBV line level standards, with studio gear and consumer devices as examples, and learn how to select the level to prevent misalignment.

Identify instrument level as the input for outputs from electric guitars, basses, synths, and keyboards. Use the instrument switch to select instrument level, which has higher impedance than line level.

Explore how direct injection boxes enable instruments to connect to microphone inputs by reformatting signal, matching impedance, and delivering balanced mic-level outputs for clean, transparent sound.

Discover unbalanced cables, like instrument and RCA cables, for guitars, basses, and synths. Learn how tip and center wire carry audio while the surrounding shield minimizes interference.

Balanced cables carry a signal on hot and a polarity-inverted duplicate on cold, with shield. At interface, the cold inverts again, canceling noise and doubling the signal to six decibels.

Explore how dynamic microphones, a passive type that requires no phantom power, capture sound by moving a coil through a magnetic field for close-range, rugged handheld use.

Examine phantom power, typically 48 volts, powering condenser microphones and active DI boxes while maintaining balanced signal via hot and cold wires and a differential amplifier.

Compare the condenser, dynamic, and ribbon microphones to hear how high-frequency response, sibilance, warmth, and room ambience differ in practical use.

The lecture compares condenser, dynamic, and ribbon mics for guitar, highlighting body resonance, bass and low-mid frequencies, and the plucky percussive finger strokes.

Understand how the proximity effect boosts bass in directional microphones like cardioid, hyper cardioid, and figure of eight at close range, while omni directional microphones remain unaffected.

Explore how a noise gate and expander shape a drum mix by muting sounds below a threshold, adjusting attack, release, hold, and range to isolate snare from kick and hats.

Explore how a compressor reduces loud signals using threshold and ratio, contrasting it with a gate, and how attack and release shape gain reduction and the nonlinear dynamic range.

Explore how attack and release times shape snare and kick transients, from aggressive 9 to 1 compression to letting the kick breathe for a tighter, thuddier rhythm.

Explain how dynamic range compression thickens dialogue for radio, podcasts, and film, using threshold, ratio, attack, and release to balance loud and quiet sounds and hint at parallel compression.

Explore parallel compression for drums by blending a compressed and an uncompressed drum track to thicken the overall sound while preserving natural dynamics.

Explore side chain compression, where a compressor applies gain reduction to one signal while triggered by a different secondary signal, with a dialogue example and the concept of triggering signals.

Apply side-chain dynamic range compression to dialogue by triggering a compressor on one track from a filtered secondary signal on bus one, exploring de-essing and on-channel sidechain options.

Apply sidechain compression by routing the synth to a kick-triggered compressor, causing the synth to duck in time with the kick and shaping rhythm with attack and release.

Explore how reverb simulates room acoustics, control decay time, pre delay, and wet/dry mix, and hear plate, spring, and various plugin reverbs in Pro Tools examples.

Tune the reverb tail on drum hits to finish before the next snare, aiming for about 600–660 ms to avoid overlap.

Learn to route reverb via a dedicated auxiliary return instead of inserting on a channel, using sends in Pro Tools to control wet signals for drums, kicks, and overheads.

Explain pre vs post fader sends and how they affect signal routing to reverb and headphone feeds, showing how dry/wet balances change with fader position.

Master delay as a discrete echo by routing to an auxiliary guitar delay, tuning mix, time, and feedback, and exploring wow, flutter, and EQ options.

Explore the chorus effect, duplicating a sound with small timing and pitch variations controlled by rate and depth to create rich textures on guitar or backing vocals.

Explore the flange, a fluctuating comb filter that duplicates a sound and moves its delay to sculpt moving frequencies that get cut and boosted, with mix, rate, and depth controls.

Explore how distortion adds harmonics and bite, placing it in line to help drums and bass punch through a mix, using air distortion, fab filter, saturation, tape models, without overuse.

Explore tape saturation with an analog-inspired plug-in, adjusting drive, speed, and bias to shape subtle distortion, hiss, and warmth on drums and bass while balancing input and output.

Explore how two-channel stereo creates the phantom center using amplitude-based panning across left and right speakers or headphones, revealing the illusion of sound position.

Explore how two ears and our brain localize sound using volume and timing differences, and why low frequencies rely on timing differences, not just amplitude-based panning in Pro-Tools.

Explore how diffraction makes sound bend around objects, creating acoustic shadows and explaining how high frequencies vs low frequencies behave, plus practical examples like the pencil trick and subwoofers.

Compare stereo over speakers and headphones, focusing on how volume and timing cues and head diffraction affect localization. Learn why low frequencies feel odd when panned left on headphones.

explain how a single microphone collapses two sounds into a central point, losing positional information, and how stereo mic arrays—xy cross-angled and spaced—preserve spatial imagery through amplitude and timing differences.

Final recap of audio engineering fundamentals; explore three-dimensional sound, frequency ranges, phase relationships, mic types, signal levels, EQ, dynamics, reverb, and practical DAW recording tips.