Publication in the Diário da República: Aviso n.º 23177/2023 de 30/11/2023
6 ECTS; 1º Ano, Anual, 70,0 TP , Cód. 66591.
Lecturer
- Carlos Alberto Farinha Ferreira (1)(2)
(1) Lead Professor
(2) Teaching Professor
Prerequisites
Not applicable.
Objectives
- To introduce the principles governing sound waves.
- To foster an understanding of acoustic propagation phenomena and their effects and consequences in audio capture and reproduction applications.
- To promote the understanding and practical application of techniques and technologies for capturing, processing, and reproducing audio in its various aspects.
Program
1 Introduction
General introduction to the topic and its context within the course. Historical overview and evolution.
2 Basic Concepts
Sound production and pressure/velocity relationships. Frequency, wavelength, propagation speed, and impedance. Sound pressure, intensity, and power. Logarithmic scale and its use. Propagation: spherical and plane wave radiation. Interference and reflections, transmission and reflection coefficients, diffraction, refraction, and sound diffusion. Practical consequences of the previous effects: directivity, delay, echo, etc.
3 Hearing and Speech
Anatomy of the ear. Transmission and encoding along the auditory-cerebral system. The ear and its properties. Hearing loss. Source location, perception of reflections. The voice and its properties.
4 Filters and Diffusers
Distributed and concentrated parameters, electromechanical analogies. Combination filters, half-wave and quarter-wave resonators. Helmholtz resonators. Diffusers.
5 Electroacoustic Transduction
Transmitters, receivers and amplification, technologies, operating principles and characteristics. Parameters of electrodynamic loudspeakers and their relation to applications. Closed acoustic enclosures, bass-reflex and others.
6 Room Acoustics
Concept of reverberation and reverberation times, absorption coefficients. Relationships between direct and reverberated signals. Normal modes, standing waves and frequency distribution of resonances. Acoustic factors in building design and materials used. Specifications and measures for noise reduction and isolation for airborne noise (mass law) and impact noise, their relation to construction and materials used.
7 Sound Engineering and Production
Equipment used and its operation and adjustment.
Indoor and outdoor recording and factors involved: reverberation time; isolation; echo; microphone directivity; wind noise; traffic and background noise, etc.
Treatment, production and mixing: track organization, gain and frequency correction. Effects (reverberation, delay, etc.), compressors and limiters. Audio restoration in editing (removal of clicks, background noise, electrical "hum", cuts, temporal alignment).
Live system adjustment: standardization of sound coverage and positioning of loudspeaker groups. Microphone audio feedback control.
8 Noise and Acoustics of the Environment.
Effects of noise.
General noise, and noise from installations and equipment; noise reduction studies and methods. Legislation. A weighting frequency-filtering. Measuring equipment, and diagnostic and control methods.
Evaluation Methodology
The final grade calculation is made considering the following weightings:
- Written test (attendance or exam): 50%;
- Research paper and presentation: 25%;
- Practical work: 25%;
The student passes when they obtain a final grade equal to or higher than 10 on a scale of 20.
The grades for the research paper and the practical work are valid at any time of evaluation.
There is an evaluation during the attendance period.
Bibliography
- E. Kinsler, L. e R. Frey, A. e B. Coppens, A. e V. Sanders, J. (2000). Fundamentals of Acoustics. U.S.A.: J. Wiley & Sons
- F., A. e Ken, P. (2009). Master Handbook of Acoustics. -: McGraw Hill Professional
- Gary, D. e Ralph, J. (1990). The Sound Reinforcement Handbook. USA: Hal Leonard Publishing Corporation
- Harley, R. (2021). The Complete Guide to High End Audio. U.S: Acapella Publishing
Teaching Method
Theoretical concepts are presented and explained by the teacher, often based on practical experiences. Problem-solving, and the use of systems in application cases, complement the teaching of the principles in question.
Software used in class
To be defined.
