Audio Theory Fundamentals for Sound Design

Explore how sound moves from acoustic air to electrical waveform to digital form. Identify the roles of physical vibration and electromagnetic signals in sound design.

Explore how waveforms depict electrical and acoustic signals, including mono and stereo channels, the zero volts line, and how microphone diaphragms, digital samples, and speaker movement shape playback.

Discover how frequency shapes pitch, from 20 Hz to 20 kHz, and how complex sounds emerge from multiple frequencies, with real-time spectrum visuals and references to sub and high frequencies.

Explore the frequency spectrum from 20 Hz to 20 kHz, with bands like sub bass, bass, low mids, mids, treble, and air, and hear how isolating them shapes sound.

Explore how we hear the frequency spectrum nonlinearly, grasp logarithmic perception, and connect octaves and pitch increments to Hz doublings.

Define amplitude versus loudness and demonstrate decibels as a logarithmic measure for communicating amplitude differences, including dBFS and dB SPL.

Explore how frequency and amplitude shape perceived loudness across the spectrum, including equal loudness contours, thresholds of hearing, and the 3 to 4 kHz baby crying range.

Capture how waveforms represent acoustic fronts, microphone diaphragm movement, and the audio instruction for playback, while introducing frequency in hertz and kilohertz and the role of decibels in sound design.

Learn how speakers cannot reproduce entire frequency ranges, how two-way and three-way monitors with crossovers split lows, mids, highs, and how room acoustics and headphones shape monitoring.

Compare open-back and closed-back headphones with speakers, explaining isolation, stereo imaging, and room acoustics effects. Emphasize that headphones are recommended for beginners, yet have limited low frequencies.

Explore how two or more sounds add or subtract their waveforms and how polarity inversion can cause complete cancellation, making the mix a single sound.

Learn polarity inversion, the process of flipping a waveform to test for nulls and cancellation, and its use in identifying identical sounds and correcting microphone polarity in multi-mic setups.

Explore phase and phase cancellation in sound design, from sine waves to complex multi-frequency signals, and learn how time shifts, mic placement, and reflections cause cancellation and comb filtering.

Explore comb filtering as phase cancellations from time shifts between sound copies, with 1 ms delay. Use pink noise and spectrograms to diagnose copies.

Explore wavelength as the physical length of one sine-wave cycle, how speed of sound and temperature affect it, and how to predict phase cancellations and comb filtering in mic setups.

Explore how two-way speaker systems reproduce the full spectrum. Compare headphones and speakers for subbass, stereo image, phase, polarity, and the null test.

Explore how stereo creates a phantom center by balancing left and right volumes. Low frequencies rely on timing cues, high frequencies on amplitude cues, and panning shapes the phantom image.

this lecture introduces signal processing and four categories—volume altering, dynamics, spatial processing, and sound altering—emphasizing goal-oriented use of eq, compressor, and effects.

Explore how equalizers shape sound by boosting or cutting specific frequencies using bell curves, shelves, and filters; compare high pass, low pass, and bandpass effects with q control.

Explore compressors and limiters as dynamic processors, detailing threshold, ratio, attack, release, and output gain, and contrast brick wall limiting with flexible compression to shape transients.

Explore compression techniques for sound design through practical exercises that reduce peaks, control transients, preserve or alter reverb tails, and compare different compressors to shape the pa and dialogue sounds.

Explore how distortion and saturation shape sound by pushing signals beyond their comfortable amplitude, creating harmonics that add brightness, edge, and musical qualities in mixing and sound design.

Explore harmonics and their link to musical theory, including octave relationships (doubling frequencies), fundamental pitch, and how odd and even harmonics shape timbre and distortion.

Explore how distortion adds odd and even harmonics to a tone, sharpening brightness. The demo compares modes and shows making low frequencies more audible in a mix.

Learn how small loudness differences, like 0.5 dB, can bias your evaluation of distortion plugins and sound design, and practice isolating processing from volume.

Explore string harmonics on a guitar, isolate specific harmonics with pro-q, and sculpt the harmonic profile by boosting or carving away fundamentals and overtones to shape tone.

Explore how reverb simulates room reflections, influenced by space size, surface materials, and shape, with diffusion, damping, and pre-delay shaping the reverb time and frequency response.

Explore practical reverb techniques for sound design, using a dedicated reverb channel in parallel with the dry signal, and shaping living room, bathroom, and church atmospheres.

Explore mechanical reverb as a physical and spring plate alternative to acoustic reverb. Learn how plate reverbs create metallic resonances and how plug-in emulations fit into sound design workflows.

Explore convolution reverb, a natural, real-space effect built from impulse responses of actual rooms and plates, captured by clap or sine sweep techniques.

Explore delay creates distant echoes by adjusting time between repeats and feedback, and route signals in Reaper to feed repeats into diffusion and convolution reverb for dry and wet balance.

Explore chorus and its choir-like timing, pitch, and timbre variations to widen the stereo image and thicken mono sources; use for robotic or monstrous dialogue and shimmering textures.

Explore phaser and flanger to create moving comb filter effects, compare phase rotations with time-based differences, and emulate rotary speaker sounds for spacey textures.

Review core signal processing concepts from volume adjustments to eq and compression, then explore reverb, delay, and diffusion to shape space and texture.

Explore digital audio theory with a photo analogy, linking samples, bit depth, noise floor, and sampling rate. See how sampling rate shapes high frequencies and bit depth governs dynamic range.

Discover how digital audio converts analog waves to data by sampling voltage, and how 16-, 24-, 32-bit depth and 44.1k/48k rates shape fidelity.

Explore the Nyquist theorem and how 44.1 and 48 kHz suit voice recording, while higher rates like 192 kHz enable wild sound design and pitch shifting.

Understand sample rate conversion strategies by keeping to base families (44.1 and 48 kHz) and using clean multiples (88.2/176.4 or 96/192) aligned to the destination.

Bit depth determines how many values a digital sample can take, affecting dynamic range. Record and mix at 24 bit, convert to 16 bit at the end to minimize noise.

Discover how 32 bit floating point scales beyond fixed-point limits, reducing distortion and preserving data. See 120 dB gain demonstrations and post-production undistortion with izotope rx.

Discover how modern daws use internal floating point processing (32- or 64-bit) even in 24-bit sessions, enabling undistorted sound through on-the-fly gain changes and 32-bit recording becoming common since 2019.

Explore how lowering sample rate and bit depth shapes frequency response and dynamic range, then apply the kilohertz bitcrusher plugin to create glitchy, sci-fi sounds through automation.

Review digital audio concepts, including sample rate, bit depth, and dynamic range, from 44.1/48 kHz real-time work to 192 kHz sound design, and note 24-bit as standard with 16-bit discouraged.

Learn how aliasing occurs when recording above the Nyquist frequency and how oversampling with anti-aliasing filters prevents digital artifacts in high-quality audio.

Experiment with high sample rate recording at 192kHz to capture supersonic frequencies for sound design, then compare slow-downs in Pro Tools using add or convert.

Learn how dither prevents audible stuttering when converting from 24-bit to 16-bit by adding -96dB noise with noise shaping at the final stage of the signal chain.

Discover that multiple eq instances are interchangeable in order; learn how linear phase eq mitigates phase differences at the cost of delay and pre-ringing.

Explore dynamic eq and multiband compression as two dynamic approaches to shaping sound. Learn how dynamic eq responds to input to carve bass on demand, while multiband compression targets bands.

Apply polarity inversion to compare two sounds and reveal differences by summing inverted and original signals, producing a null test difference output that shows when sounds are not identical.

Explain how lossy audio codecs compress and decompress on playback, trading quality for smaller file sizes, with mp3 and ogg vorbis as examples and bitrate ranges.

Apply a null test with polarity inversion to compare the original wave against lossy codecs like mp3, revealing how bitrate differences (32 kbps vs 320 kbps) alter reverb detail.

Review oversampling to push Nyquist and prevent aliasing. Explore how distortion, harmonics, compression, and dither create new frequencies and affect phase and eq.

Explore microphone categories and their unique properties for practical recording applications, learn about microphone preamplifiers, and understand when and how to record in stereo.

Handheld recorders provide an all-in-one portable recording solution that covers the signal chain. Ideal for beginners, they offer stereo capture with two condensers, built-in mic preamp, adc, and onboard storage.

Explore dynamic, condenser, and ribbon microphones for sound design, noting condensers' bright high frequencies, dynamics' rugged SPL tolerance, and ribbons' warm tone with strong transients.

Adapt to different tonal qualities within about five seconds after switching microphones. Pause for seven seconds to reset memory and regain objective tone judgments.

Explores polar patterns and how microphone pickup varies with direction from omnidirectional to cardioid. Demonstrates hypercardioid and figure-of-eight patterns, explains front and rear sensitivity, and references polar plots.

Explore the cardioid polar pattern as the standard front-facing microphone pickup, its three-dimensional behavior, off-axis variability, and the unpredictable reverberant responses that contrast with omnidirectional stability.

Explore the proximity effect, where bass rises near the source and thins when far, and note that omnidirectional mics avoid this effect compared with directional mics.

Explore hypercardioid and supercardioid patterns, noting their similarity yet distinct rear rejection and narrower pickup than cardioid; learn how proximity effect and rejection angles influence outdoor mic positioning.

Shotgun microphones are long, highly directional mics with an interference tube for outdoor boom work, while indoors, reflections limit their usefulness and wind protection is key.

Learn how to use a lightweight carbon fiber boom pole for location sound, minimize handling noise, manage coiled cables, and extend from the top for flexible one-handed operation.

Learn to mitigate outdoor wind in audio using foam windscreens, honeycomb windshields, and wind socks, balancing wind reduction with high-frequency loss for reliable field recording.

Recognize wind distortion across the frequency spectrum that complicates recordings, and note that high-pass filtering only partially helps. Explore the importance of wind shielding and removing wind before recording.

Master the figure of eight polar pattern, capturing front and back equally with strong side rejection and pronounced proximity effect for isolation and natural reverb.

Explore proximity effect on plosives with a figure of eight and a hypercardioid microphone, and how a pop shield, acoustically transparent, protects close mic vocal recordings by dispersing air.

Explore lavalier (lapel) microphones, their omnidirectional condenser design, practical use in film and television, and how wireless, hidden placements reduce plosives and wind distortion for dialogue and sound design.

Learn about plug-on transmitters with XLR inputs, wireless lavalier use, 48V power requirements limiting to passive mics, and digital transmitters with onboard recording and SD card options.

Explore how balanced microphone cables reject noise along the length of the cable using hot and cold signals, balanced XLR inputs and outputs, and a differential amplifier.

Demonstrate using a cable tester to verify xlr cables by confirming pin 1 to pin 1, pin 2 to pin 2, and pin 3 to pin 3, ensuring signal paths.

Discover why microphone signals need a mic preamp to boost mic-level to line-level for usable sound, and how interfaces and field recorders integrate preamps with XLR and TRS options.

Learn to navigate mic, line, and speaker level signals, using mic preamps, DI boxes, and power amplifiers to route audio through EQs, compressors, effects units, and powered or passive monitors.

Explore audio interfaces as the all-in-one solution to monitor, record, and listen; understand mic and line inputs, monitor and line outs, DI box emulation, and analog‑to‑digital conversions.

Explain how di boxes interface mic inputs with non-microphone sources like keyboards and guitars by converting unbalanced high impedance instrument level signals to balanced low-impedance mic level signals.

Trace the recording chain from acoustic waves to mic level, through XLR cables and a preamp to line level, then into a computer via an interface and phantom-powered mics.

Explore input and output impedance and the bridging principle in audio, learn why higher input impedance than output improves signal transfer, and see practical di box examples.

Design mono recording principles by recognizing sound as three-dimensional, while a microphone captures a zero-dimensional projection at a single point, shaping stereo considerations.

Learn how stereo adds the left-right dimension on top of mono, while height and distance cues come from amplitude and reverberation. Discover how panning uses inter-channel level differences.

Explore the xy stereo array for stereo recording, crossing capsules at 90 degrees to achieve phase-coherent center panning, capturing movement and spatial tonal differences, as with acoustic guitar.

Learn how stereo perception uses amplitude and timing differences, and how the xy array emphasizes amplitude cues, with low frequencies relying on timing and high frequencies using both.

Explore the Haas effect, or precedence effect, where the first-arriving sound determines perceived direction. Learn how timing differences affect localization and why Haas panning risks phase issues and comb filtering.

ORTF uses a two-m microphone array to capture left-right timing and amplitude differences for wide sources, but is not ideal for close sources and may cause comb filtering if mono.

Explore mid-side recording, compare traditional omni and cardioid mid-side, and learn how mid and side decode to left and right with polarity inversion, shaping stereo width.

Examine how room acoustics affect listening and recording environments, addressing bass frequency misrepresentation, reverb, and reflections, and use headphone testing to reveal issues with room response.

Explore room resonances and standing waves in bass frequencies, and learn to reduce them with corner bass traps and optimized listening position.

Conduct a 20 Hz to 20 kHz sine sweep in your room, record at listening position, and use spectrum analysis to identify standing waves, dips, and boosts.

Tune room reverberation in your listening space by using bass traps and foam or fiberglass panels, evaluating with music rather than relying on RT60 measurements.

Place acoustic panels at the first reflection points to create a reflection free zone, reducing reverb and mitigating comb filtering from early reflections.

Master room acoustics by identifying low-frequency resonances and room reflections, using bass traps first and panels for first-reflection zones, then verify with headphones and speakers.

Explore ambience, Foley, and practical strategies for sound design in this concise introduction to audio theory fundamentals.

Apply three sound design strategies: record the same object, source from a library, or create a sonically equivalent substitute, then evaluate feasibility and impact.

Explore the synchronicity of vision and audio, contrasting light's speed with sound, and experiment with delays (5 ms, 20 ms, 40 ms) to shape natural or creative timing.

Explore how ambience shapes time perception in film and games. Use seamless ambience for real-time continuity, ambience jumps for time passage, or no ambience to imply time is not represented.

Explore how ambience conveys emotion and context in sound design by signaling time of day, weather, geography, and mood, while shaping characters' perspectives through ambient presence and cuts.

Apply the rule of two and a half, Walter Murch concept, to analyze how brain tracks synchrony among footsteps within a scene, and practice syncing footsteps in a DAW.