Julius O. Smith III: Legendary Professor of DSP (CCRMA, NeXT, Shazam, GeoShred) | WolfTalk #034

CCRMA, NeXT, Yamaha synths, resampling, physical modeling, digital waveguides, virtual analog, and AI: a lifetime of turning DSP research into musical tools.

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Introduction

When discussing DSP resources, his books come up most often.

When browsing DSP publications related to music, his name is all over the place (as author, co-author, or in citations).

It’s hard to list what he’s done, because he’s done so much.

Professor Julius Orion Smith III needs no introduction. He’s been at the renowned CCRMA at Stanford University since the beginning, first as a PhD student and then as a professor. He worked with Steve Jobs on the NeXT computer. He developed digital waveguide synthesis used in some of Yamaha’s synthesizers. He worked on the Shazam audio fingerprinting algorithm. He’s written four free DSP textbooks. He’s authored or co-authored hundreds of publications. And on, and on, and on.

Needless to say, it was my dream since starting this podcast to interview him. Listen to the interview to find out how you can profit from my joy 😉

Note: If you like the podcast so far, please go to Apple Podcasts and leave me a review there. You can do so on Spotify as well. It will benefit both sides: more reviews mean a broader reach on Apple Podcasts, and feedback can help me to improve the show and deliver better-quality content to you. You can also subscribe and give a like on YouTube. Thank you for doing this 🙏

Episode contents

From this episode, you will learn:

• How Julius Smith became one of the world’s most well-known and respected DSP professors
• The story of CCRMA at Stanford University
• Behind-the-scenes of the music features of the NeXT computer
• The story of Yamaha synthesizer development (FM and physical modeling)
• The story of Shazam and GeoShred music apps
• How to learn DSP well
• How to do excellent DSP research
• How Julius uses AI for research, learning & programming

This episode was recorded on September 23, 2026.

Audio post-production, mixing & mastering by Sathira Tennakoon. Video edited by Vadzim Vezhnavets.

References

People

1. Julius O. Smith III
   • Personal website (CCRMA)
   • Stanford Music faculty page
   • Publications
   • Google Scholar
   • GitHub
2. At Rice University
   • C. Sidney Burrus
   • Thomas W. Parks
   • James Boyd Pearson
3. Stanford AI Lab and early computer music
   • John McCarthy
   • Max Mathews
   • John Chowning
   • Leland Smith
   • James A. “Andy” Moorer
   • John M. Grey
   • Peter Samson
   • Stewart Nelson
   • F. Richard (Dick) Moore
   • John R. Pierce
4. At NeXT and Sun Microsystems
   • Steve Jobs
   • Andy Bechtolsheim
   • David A. Jaffe
   • Michael McNabb
5. CCRMA colleagues
   • Chris Chafe
   • Jonathan Berger
   • Ge Wang
   • Takako Fujioka
   • Jonathan Abel
   • Marina Bosi
   • Dave Berners
   • Malcolm Slaney
   • Xavier Serra
6. Students, collaborators, and co-authors
   • Kurt Werner
   • Tim Stilson
   • Guillermo Garcia
   • Avery Wang
   • Phil Gossett
   • Pablo Tablas de Paula
   • Vesa Välimäki
   • Josh Reiss
7. DSP textbook authors and MATLAB creators
   • Alan V. Oppenheim
   • Ronald W. Schafer
   • Lawrence R. Rabiner
   • Bernard (Ben) Gold
   • Cleve Moler
   • Jack Little
8. Researchers and educators
   • Stefan Bilbao
   • Meinard Müller
   • Julian Storer
   • Gary Kendall
   • Manfred R. Schroeder
   • Gilbert Strang
   • Andrej Karpathy
   • Perry R. Cook
   • Gary Scavone
9. Physical modeling and network theory pioneers
   • Jean le Rond d’Alembert (1747)
   • Joseph-Louis Lagrange (1759)
   • Augustin-Jean Fresnel (1823)
   • James Clerk Maxwell (1855–1865)
   • Lord Rayleigh (John William Strutt) (1871)
   • Oliver Heaviside (1886)
   • Vitold Belevitch (1945)
10. Instrument makers
    • Jordan Rudess
    • Pat Scandalis
    • Nicholas J. “Nick” Porcaro
    • Rob Fielding
    • Bob Moog
11. Stanford technology licensing
    • David Lovejoy
    • Joe Koepnick

Julius’ projects

Books

• DSP book series overview
  • Mathematics of the Discrete Fourier Transform (DFT)
  • Introduction to Digital Filters with Audio Applications
  • Physical Audio Signal Processing
  • Spectral Audio Signal Processing
• Digital Audio Resampling home page

Courses and teaching

• Music 320: Introduction to Audio Signal Processing
• Music 320C: Audio DSP Projects in Faust and C++
• Music 423: Music/Audio Signal Processing Research Seminar
  • Music 423: AI audio signal processing reading list
• AI Miracle Decade+
• AI Foundations
• Courses: AI-tutored course templates (GitHub)

Software and instruments

• moForte
  • GeoShred
  • moForte Guitar
• Staccato Systems
  • SynthBuilder
• Faust virtualAnalog example (Minimoog-style synthesizer)
• l2hmj (LaTeX2HTML with MathJax)
• Lightning Hydra Template Extended (LHTE)
• Neural Spectral Modeling Template (NSMT)
• Python Templates for Neural Image Classification and Spectral Audio Processing (ADCx Gather 2025)

Selected papers & patents

• Techniques for Digital Filter Design and System Identification with Application to the Violin (PhD dissertation, 1983)
• Extensions of the Karplus–Strong Plucked-String Algorithm (Jaffe & Smith, 1983)
• A Flexible Sampling-Rate Conversion Method (Smith & Gossett, 1984)
• A New Approach to Digital Reverberation Using Closed Waveguide Networks (Smith, 1985)
• Music Applications of Digital Waveguides (STAN-M-39, 1987; includes Efficient Simulation of the Reed-Bore and Bow-String Mechanisms, 1986)
• Analyzing the Moog VCF with Considerations for Digital Implementation (Stilson & Smith, 1996)
• Alias-Free Digital Synthesis of Classic Analog Waveforms (Stilson & Smith, 1996)
• Fifty Years of Artificial Reverberation (Välimäki, Parker, Savioja, Smith & Abel, 2012)
• Aliasing Reduction in Neural Amp Modeling by Smoothing Activations (Sato & Smith, DAFx25)
• Four Decades of Digital Waveguides (Tablas de Paula, Smith, Välimäki & Reiss, 2026)
• Digital Signal Processing Using Waveguide Networks (US 4,984,276, Stanford)
• System and Methods for Recognizing Sound and Music Signals in High Noise and Distortion (US 6,990,453, Wang & Smith)

Companies

Audio and music technology

• Shazam
  • How Shazam IDs Over 23,000 Songs Each Minute (WSJ Tech Behind, 2023)
• Yamaha
  • Yamaha VL1
• Korg
  • Korg Kronos
• Moog Music
  • Minimoog Model D
• Smule
  • Ocarina (iPhone app)
• Audio Modeling
  • SWAM instruments
• Wizdom Music
  • MorphWiz
  • Geo Synthesizer
• Naada Instruments
• Ampeg

Computing

• NeXT
  • NeXT Computer
  • NeXT introduction (October 12, 1988)
  • NeXT Music Kit
• Sun Microsystems
• Systems Concepts
  • Samson Box (Systems Concepts Digital Synthesizer)
• MathWorks
  • MATLAB
  • Signal Processing Toolbox (MATLAB)
• Systems Control Technology, Inc. (SCT)
  • CTRL-C (SCT’s MATLAB-based product)
• Analog Devices
  • SHARC DSP
  • SHARC Audio Module (Faust integration)
• ESL (Electromagnetic Systems Laboratory)
• Xenon Microsystems (later Chromatic Research)

Universities & research labs

• Rice University
• Stanford University
  • CCRMA (Center for Computer Research in Music and Acoustics)
    • The Knoll
    • CCRMA Stage (56.8 dome loudspeaker system)
    • Stanford Laptop Orchestra (SLOrk)
    • Stanford VR Design Lab
    • Music 422: Perceptual Audio Coding
    • CCRMA Industrial Affiliates Program
  • Stanford Artificial Intelligence Laboratory (SAIL) / Computer Music Project
  • Stanford Office of Technology Licensing (OTL)
  • Stanford Honors Cooperative Program (HCP)
  • Stanford Instructional Television Network (SITN)
• Bell Labs
• MIT
  • MIT 18.06: Linear Algebra (Gilbert Strang, OpenCourseWare)
• GRAME (Grame CNCM, Lyon)

Software & frameworks

• JUCE (podcast sponsor)
  • Official JUCE audio plugin development course
  • Plugin GUI Magic (foleys_gui_magic)
• Synthesis ToolKit in C++ (STK)
• ChucK
  • Chunity (ChucK for Unity)
• GNU Octave

Historical computer music software

• MUSIC-N (including MUSIC I and MUSIC V)
• SCORE (music engraving software)
• Unix
• HyperCard

Machine learning and visualization

• PyTorch
  • PyTorch Lightning
• Lightning-Hydra-Template
• Manim Community Edition

Typesetting and web publishing

• TeX
• LaTeX
• LaTeX2HTML
• MathJax

AI tools & models

Coding agents

• Claude Code
  • CLAUDE.md
  • Claude Code subagents
• Hermes Agent (Nous Research)
• Cursor

Models

• Claude (Anthropic)
  • Claude Opus 5.5
  • Claude Fable 5.1
  • Claude Sonnet
• GPT-6 Astra (OpenAI)

Developer tools

• git worktree
• Git submodules
• Git --reference and alternates (shared object stores)
• iTerm2
• GoodReader

Programming languages

• Fortran
• SAIL (Stanford Artificial Intelligence Language, ALGOL-based)
• Lisp
• Assembly language (Motorola DSP56000)
• Objective-C
• C
• C++
• Python
• Faust

Hardware

Historical computers

• IBM 704
• PDP-1
• PDP-6
• DEC PDP-10 KL10 processor
• PDP-11/45
• SUN workstation board (Stanford University Network)
• Motorola DSP56001

Audio and instruments

• PCM adaptors (digital audio on Betamax video cassettes)
• Silvertone guitar
• Boss OC-2 Octave
• iPad 2

Technical concepts

Most links below go to the relevant chapter of Julius’ free online books.

Sampling and resampling

• Bandlimited interpolation
  • Sampling theorem
• Window method for FIR filter design
• Fast convolution (FFT convolution)

Physical modeling and synthesis

• Physical modeling synthesis
• Wave equation for a vibrating string
  • Traveling-wave solution of the wave equation
• Port-Hamiltonian modeling
• Karplus–Strong algorithm
• Bowed-string and violin synthesis
  • Digital waveguide bowed-string model
• Waveguide clarinet model
• Coupled string, body, and neck modes
• Electric guitar modeling
• Jawari (javari) bridge
• Modal synthesis
• FM synthesis
• Synthesizer sound matching: spectrogram-to-parameter estimation

Waveguides and wave digital filters

• Digital waveguides
  • Digital waveguide networks
• Waveguide reverberation / delay effect
• Wave impedance and scattering (reflection and transmission)
  • Kelly–Lochbaum scattering junctions
• Lossless scattering and reversible delay networks
• Schroeder allpass filters
• Wave digital filters
• Delay-free loops and reflection-free ports
• Finite-difference schemes
• Bilinear transform
  • Bilinear-transform frequency warping

Spectral processing and perception

• Heterodyne filter (heterodyne-comb) analysis
• Short-time Fourier transform (STFT)
  • Spectrograms
• Phase vocoder (FFT vocoders)
• Sinusoidal tracking
• Modulation spectrograms
• Perceptual audio coding (MPEG audio)

Audio fingerprinting

• Spectral peak constellations
• Combinatorial hashing of spectral peak pairs

Virtual analog and effects

• Virtual analog modeling
• Moog VCF (ladder filter)
• Power-normalized ladder filters
• Neural amplifier modeling
• Tube amplifier modeling
• Physically modeled speaker cabinets

Programming and research practice

• Hallucination (AI)
• Faust foreign functions (ffunction)
• Undefined behavior
• SND research heuristic: S / (N × D)

Books & resources

DSP and computer music books

• Digital Signal Processing (Oppenheim & Schafer, 1975)
• Theory and Application of Digital Signal Processing (Rabiner & Gold, 1975)
• Classical Network Theory (Vitold Belevitch, 1968)
• Introduction to Digital Audio Coding and Standards (Bosi & Goldberg)
• DAFX: Digital Audio Effects (edited by Udo Zölzer)
• Numerical Sound Synthesis (Stefan Bilbao, 2009)
• The Sound of Innovation: Stanford and the Computer Music Revolution (Andrew J. Nelson, 2015)

Courses, channels, and journals

• 3Blue1Brown
• Music Processing – Analysis (Meinard Müller, FAU / AudioLabs)
• Computer Music Journal
• UUO Manual (SAIL Operating Note 55)

Papers & research

• “The Digital Computer as a Musical Instrument” (Mathews, Science, 1963)
• FM synthesis patent (US 4,018,121, John Chowning)
• On the Oscillations of Musical Instruments (McIntyre, Schumacher & Woodhouse, 1983)
• Piano modeling literature
• Instantaneous and Frequency-Warped Signal Processing Techniques for Auditory Source Separation (Avery Wang, PhD thesis, 1994)
• An Industrial-Strength Audio Search Algorithm (Avery Wang, ISMIR 2003)
• Optimal Filter Partition for Efficient Convolution with Short Input/Output Delay (Guillermo Garcia)
• Efficiently-Variable Non-Oversampled Algorithms in Virtual-Analog Music Synthesis (Tim Stilson, PhD thesis, 2006)
• Unearthing the Physicality of Instrumental Timbre (Han Han, PhD thesis, 2025)

Conferences & communities

• DAFx proceedings (paper archive)
• ICMC (International Computer Music Conference)
• AES (Audio Engineering Society)
• Acoustical Society of America (ASA)
• ICASSP (IEEE International Conference on Acoustics, Speech, and Signal Processing)
• WASPAA (IEEE Workshop on Applications of Signal Processing to Audio and Acoustics)
• International Symposium on Musical Acoustics (ISMA)
• ISMIR 2026
• Audio Developer Conference (ADC)
• CCRMA Hearing Seminar

Music & cultural references

Musicians

• Andy Timmons
  • “Ghost of You” — Andy Timmons Band, Resolution (2006)
• Neal Morse
• Mike Portnoy
• Steve Morse
• Roine Stolt
• Eric Gillette
• Randy George

Recordings and musical examples

• Bach: Violin Concerto in A minor, BWV 1041 (NeXT launch demo)
• Silicon Valley Breakdown (David A. Jaffe)
• Invisible Cities — “City of Reflection” finale (Michael McNabb)
• The Beatles
  • “I Should Have Known Better” (The Beatles)

Bands and influences

• Dream Theater
  • Lifting Shadows: The Authorized Biography of Dream Theater (Rich Wilson)
• Dixie Dregs
• Yes
• Emerson, Lake & Palmer
• Marillion
• Flying Colors
• Transatlantic
  • “The Final Medley” — Transatlantic, The Final Flight: Live at L’Olympia (2023; recorded in Paris, 2022)
• The Flower Kings
• The Neal Morse Band

Thank you for listening! 🙏