Communication Acoustics

1. Fundamentals of acoustics (Müller, Vorländer) 1.1 sound field quantities, wave equation 1.2 plane waves / spherical waves 1.3 energy/intensity, decibel 1.4 sound sources: voice / musical instruments / noise 1.5 sound reflection, absorption, diffraction 1.6 statistical room acoustics, reverberation

2. Fundamentals of signals and systems (Ahrens) 2.1 Complex notation, harmonic signals 2.2 Fourier series, Fourier transformation, time and frequency domain (DFT, FFT) 2.3 LTI systems, impulse response and transfer function 2.4 Digital filters 2.5 Short introduction to non-linear systems

3. Anatomy and physiology of the hearing system (Fels) 3.1 Peripheral auditory system 3.2 Physical binaural cues and binaural hearing 3.3 Fundamentals of binaural technology 3.4 Reproduction of binaural recordings

4. Psychoacoustics (Seeber)

• Hearing threshold
• Auditory masking
• Auditory frequency selectivity and critical bands
• Loudness of sounds
• Pitch, pitch strength, and timbre
• Sharpness
• Fluctuation strength and roughness
• Binaural unmasking for speech understanding
• Psychoacoustic methods

5. Electroacoustics (Altinsoy) 5.1 Introduction to electroacoustical systems and transmission 5.2 Electromechanical and electroacoustical analogies 5.3 Amplitude frequency response, harmonic distortion, intermodulation distortion, noise level and signal-to-noise ration 5.4 Transducer principles 5.5 Microphones 5.6 Loudspeakers 5.7 Headphones and earphones

6. Speech acoustics (Möller) 6.1 Anatomy of the human speech production system 6.2 Excitation (periodic excitation: mechanism, fundamental frequency, spectrum; aperiodic excitation: noisy excitation, step function) 6.3 Sound shaping 6.4 Speech signal characteristics 6.5 Speech sounds 6.6 Models of speech production 6.7 Speech signal analysis 6.8 Speech intelligibility

7. Sound recording and reproduction (Weinzierl) 7.1 The psychoacoustics of stereophonic reproduction 7.2 Reproduction formats: From 1.0 to 24.1.10 7.3 Recording techniques 7.4 Channel-oriented vs. object-oriented spatial audio coding

8. Virtual acoustics I: Binaural technology (Weinzierl) 8.1 The concept of binaural recording and reproduction 8.2 Recording and playback devices 8.3 Dynamic binaural synthesis and re-synthesis 8.4 On the quality of virtual acoustic environments

9. Virtual acoustics II: Sound field analysis and synthesis (Ahrens) spatial rendering: loudspeaker arrays; spatial capture: microphone arrays, beamforming

10. Application Room Acoustics 1 (Müller) Geometrical acoustics, impulse responses, perception (ISO 3382 parameters), examples of performance spaces and classrooms

11. Application Room Acoustics 2 (Vorländer) 11.1 Room impulse response, image source model 11.2 Ray Tracing model 11.3 Wave models, hybrid geom/wave models 11.4 Input data,: sources and boundary conditions, precision 11.5 Auralization and Virtual Acoustics 11.6 Interfaces to 3D audio

12. Application Automatic Speech Recognition (Möller) Principle of speech recognition, architecture of a speech recognizer, feature extraction, Hidden Markov Models, language models

13. Application Text-to-Speech Synthesis (Möller) Historic approaches, structure of a speech synthesizer, symbolic preprocessing, prosody generation, signal generation approaches: parametric, concatenative, unit-selection synthesis

14. Application of Psychoacoustics in Product Development (Altinsoy)

15. Product Sound Design (Altinsoy)

16. Application: Perceptual Audio Coding (Ahrens) (mp3)

Fundamental knowledge and understanding in the covered areas of fundamentals of acoustics, sound propagation, audio technology, sound production, speech processing, psychoacoustics and communication acoustics. Ability to individually solve problems in communication acoustics.

The written examination (90 min) will cover material from the wide topical range of the module which is aimed at providing a general understanding of communication acoustics, audio technology and auditory preception. Understanding and the individual ability to solve problems will be examined in a 90 minute-long written exam through solving numerical problems and answering in-depth and tranfer questions about acoustical communication.

Lecture as online videotutorial Exercise as online videotutorial and online exercise Prof. Bernhard Seeber (TUM); Prof. Gerhard Müller (TUM); Prof. Michael Vorländer (RWTH Aachen); Prof. Janina Fels (RWTH Aachen); Prof. Sebastian Möller (TU Berlin); Prof. Stefan Weinzierl (TU Berlin); Dr. Jens Ahrens (TU Berlin / Göteburg); Prof. Ercan Altinsoy (TU Dresden)

Mathematics and logarithms; Fundamentals of signals and systems are helpful (will be reiterated upon in the lecture)

• Fastl, H., Zwicker, E.: Psychoacoustics - Facts and Models, 3. Auflage, Springer, Heidelberg, 2007. Yost, W.: Fundamentals of Hearing, An Introduction, 5. Auflage, Brill Academic Pub, 2013. Vorlaender, M.: Auralization. Springer, 2008. Blauert, J.: Spatial Hearing. MIT Press, 1997. Pulkki, V. and Karjalainen: Communication Acoustics. Wiley, 2015.

The module content is taught via many short video tutorials. Material for individual further study and audio examples are provided online. The exercise course deepens the understanding of the lecture content through solving numerical examples and applying it to practical problems. The exercise part is provided in video tutorials and learning progress is monitored through online questionnnaires with electronic correction. The applicability of the taught fundamentals is demonstrated on current research topics. Results and questions can be dicussed in a discussion group online with fellow students and tutors.