Sound and Music Processing

Abstract: The aim of this course is to introduce students to physical and psycho acoustics, digital audio technologies, sound processing and synthesis techniques specific for live-sound, audio and music applications. Special emphasis is placed on practice with the support of audio-specific software. 

Teaching and Learning Methods: The lecture is divided in half between the theoretical part, which is enriched by sound examples, and practice in the laboratory. 

  Course Policies: Attendance to lectures and labs is not mandatory but highly recommended. 

Description: The course will cover: physical and psycho acoustics;  fundamentals of digital audio; techniques and technologies for sound analysis, processing and synthesis and hands-on practice with dedicated audio deployment tools. 

Learning outcome: Students will be able to understand and identify the fundamental characteristics of sound for the physical and perceptual world; understand the principles of the digital audio; select and implement established signal processing and synthesis methods for sound and music signals; develop and evaluate practical sound-based applications. 

Bibliography

Fletcher, N. H., & Rossing, T. D. (1991). The physics of musical instruments. New York, Springer-Verlag.

Vaseghi, S. V. (2007). Multimedia Signal Processing: Theory and Applications in Speech, Music and Communications. J. Wiley.

Everest, F. and Pohlmann, K. (2001). Master Handbook of Acoustics. 5th ed. New York, McGraw-Hill.

Müller, M. (2015). Fundamentals of Music Processing - Audio, Analysis, Algorithms, Applications. Springer.

Course slides

Requirements: Proficiency in mathematics, physics and statistics.

Grading Policy: Exam (80%) + Lab test (20%)

Nb hours of lectures/labs: 10.5/10.5

Nb hours per week: 3

Detailed course program

Physical and Psycho acoustics

    The nature of sound waves and oscillations

        Vibration, acoustic medium and sound waves

        Atmospheric and sound pressure 

        Simple harmonic motion

        Complex amplitudes and phasors

        Superposition of harmonic motions

        Damped oscillations

        Other Simple Vibrating Systems

            A Spring of Air

            Helmholtz Resonator

            Simple Pendulum

            Electrical RLC Circuit

        Combinations of Springs and Masses

        Longitudinal and transverse oscillations

        Forced oscillations

        Continuous systems in one dimension: strings

                The normal modes of an N-mass oscillator

                Transverse Wave Equation for a String

                Travelling Waves

                Simple Harmonic Solutions to the Wave Equation

                Standing Waves

                Plucked String: Time and Frequency Analyses

    The physical and perceptual world

        The ear-brain system

        Physical vs perceived quantities

            Loudness

            Critical bands

            Sound envelope

            Pitch

            Just Noticeable Difference 

            Timbre 

        Time-frequency analysis and “playback” of audio signals

            Deterministic signals

            Periodic, Quasi-periodic, Transient 

            Stochastic stationery

            Square, Sawtooth, Triangle

            Non-periodic signal-frequency representation

            Short-time Fourier transform (STFT)

            Spectrogram

        Acoustic illusions

            The ghost fundamental

            Tartini tones (another ghost)

            Listening to the phase

            Spectral fusion

            Shepard scale

            Continuous Risset scale

Digital Audio Processing

    Audio chain in the analogue and digital worlds

    Sampling

    Sampling results in a periodic spectrum

    Quantisation and coding

    Signal-to-quantisation noise ratio (SQNR)

    The effect of digitisation on signal bandwidth 

    The effect of digitisation on real-time signal processing

Sound Processing Techniques

    Sound processing systems

    Classification of systems

    Characterisation of systems: the case of digital filtering

    Unit impulse function

    Impulse response

    The convolution operation

    Signal manipulation through audio effects

    Delay line

    Modulated delay line

    Signal manipulation through audio effects

        Effects in the space-time domain

        Vibrato

        Flanger

        Chorus

        Doubling

        Reverberation

            Comb filters

            Schroeder

    Non-linear effects

        Tremolo

        Distortion

        Compressor/Expander

    Spectral effects

        Equalisares, resonant and notch filters

    Spectral effects time variants

        Wah-wah

        Auto wah-wah

    Sound perception in space

Sound Synthesis Techniques

    Additive synthesis

    Subtractive synthesis

    Synthesis by amplitude modulation (AM) and ring modulation

    Frequency modulation synthesis (FM)

    PCM synthesis

    Granular synthesis

    Physical modelling synthesis

    Markov chains for automatic composition

Pure data - where sounds take shape 

    Intro to Pd

    Download, install and configure Pd

    Patcher Window e Pd Window

    Pd objects

    Pd connections

    Oscillators

    Bang

    Send-receive object

    Subpatches

    Oscillators: time and frequency visualisation

    Hands-on session

        Sound processing techniques

        Sound synthesis techniques