AIMS AND LEARNING OUTCOMES

The course is intended to provide students with a theoretical and practical knowledge of the most important techniques for: (i) digital sound capturing and playback, (ii) automated analysis of the audio signal in the time and frequency domains, (iii) automated analysis of music content, (iv) digital audio processing, and (v) digital synthesis of sound and music content.

At the end of the course, students are expected to know and to be able to apply the most important techniques for audio capturing and playback, sound and music analysis, and digital audio processing. In more details, the students will be able to capture an audio signal, to apply techniques for detecting the most relevant features of the signal, and for processing/modifying its content. Moreover, the students will also know the most important techniques for digital sound synthesis.

TEACHING METHODS

The module consists of lectures given by the teacher in the classroom. These include both theoretical lectures, where the teacher will use slides to present a discuss concepts and techniques with the students, and practical lectures, consisting of hands-on at the computer, and enabling students to apply the concepts and to concretely experiment the primary technologies discussed in the course.

SYLLABUS/CONTENT

1. Foundations of acoustics and psychoacoustics: sound, simple harmonic motion, equation of motion for a simple harmonic motion and its parameters. Amplitude: physical intensity of sound, perceived intensity of sound (loudness), Fletcher-Munson curves. Frequency: pure sounds, complex sounds, harmonic series (fundamental frequency, harmonics), noise, perceived frequency of sound (pitch), harmonic sounds, octaves, octave equivalence, classes of pitch, musical scales, critical bands, masking, beats. Phase: phase alignment and cancellation. Spectrum: definition, examples, introduction to the Fourier transform. Transients: envelop, ADSR. Spectrogram. Timber and timbral spaces, brightness. Sound propagation: velocity, wavelength, reflection, diffraction, refraction. Perception of spatial attributes: direction, distance, Doppler effect.
2. Acquisition, representation and storage of sound content: analog acquisition, recording and playback: acquisition devices (microphones: major typologies and features), amplifiers, recording devices, playback devices (loudspeakers: major typologies and features). Digital acquisition, recording and playback: analog to digital conversion (sampling, quantization, and coding), audio files formats, digital to analog conversion.
3. Sound analysis: audio frames, analysis of an audio signal in the time domain (algorithms for measuring sound intensity, algorithm for estimating the fundamental frequency), analysis of an audio signal in the frequency domain (algorithms for measuring timbral brightness), auditory modelling.
4. Sound processing: processing of an audio signal in the time domain (inversion, delay, variations of the dynamic range), processing of an audio signal in the frequency domain (filtering, equalization).
5. Introduction to sound synthesis: techniques for transformation, direct generation, and deformation. Examples: subtractive synthesis, additive synthesis, FM synthesis. ​

RECOMMENDED READING/BIBLIOGRAPHY

Educational material includes:

• The slides presented during classes.
• Material related to the exercises, which is made available together with each exercise.

Material can be downloaded from AulaWeb. In principle, the notes taken during the lectures and the material available on AulaWeb are sufficient for preparing for the final exam.

For students wishing to read a textbook, we recommend:

• Vincenzo Lombardo, Andrea Valle. Audio e multimedia. Apogeo.