2025Year

Intensive

Signal Representation for Acoustic Events Modeling

Lecture

Signal Representation for Acoustic Events Modeling

Z1500003 Signal Representation for Acoustic Events Modeling

NAKAJIMA Hirofumi

2.0Credits

Intensive course

Hachioji Remote

A) A high degree of specialized expertise　100%
B) The skills to use science and technology　0%
C) The ability to conduct research independently, knowledge pertaining to society and occupations, and sense of ethics required of engineers and researchers　0%
D) Creative skills in specific areas of specialization　0%

The aim of this course is to understand and practice acoustic processing based on fundamentals of acoustics. Specifically, it aims at understanding acoustic terms such as sound pressure level, frequency spectrum, understanding of signal processing concepts such as discrete Fourier transform, convolution, and acquiring skills that can be constructed by thinking about sound processing programs themselves.

The prerequisite for attending the course is that you have the basics of acoustics.

Practice Fieldwork／Support for self-learning using ICT

1. Basics of sound (1) What is the 'Acoustics' ?, propagation of sound, sound waves, sound
Goal: We aim to understand the field of acoustics, the history, the fundamentals of sound physics. With respect to the physics of sound, in addition to terms such as sound pressure, particle velocity, sound velocity, frequency, wavelength, intensity, impedance, etc., it is also necessary to acquire knowledge about sound propagation such as plane wave, spherical wave, reflection and diffraction.

2. Basics of sound (2) Sound pressure level, frequency spectrum
Goal: We aim to understand the sound pressure level as the basis of acoustic measurement and the frequency characteristics of sound. Specifically, we can calculate the value of various sound levels in everyday life, calculate RMS value from waveform, and can convert sound pressure [Pa] into sound pressure level [dB].

3. How to hear sound
Goal: We aim to understand the mechanism of perceiving sound direction and the structure of hearing. Specifically, we aim to understand the meanings of terms such as ILD, ITD, head related transfer function, and express the transfer functions of plane waves and spherical waves as mathematical expressions and explain its meaning.

4. Sound recording
Goal: Understand the types and basic structure of microphones and also explain the meanings of terms such as frequency characteristics, dynamic range, directional characteristics, actual usage of microphones that require phantom power or plug-in power, and basic principle of sound level meter.

5. Playing of sound
Goal: Understand the types and meanings of multiway speakers, bass reflex etc, as well as the type and basic structure of speakers, headphones, etc., how to connect the amplifier and speaker, the type of terminal (RCA pin, mini plug, standard plug, XLR) and so on.

6. Music and sound
Target: We aim to understand relationship between scale and frequency, tuning, chord, pronunciation principle of musical instruments, synthesis method of sound by computer etc etc.

7. Achievement evaluation (intermediate examination)

8. Representation of sound signal (1) Time domain representation, AD conversion and sampling theorem
Goal: With the understanding of AD conversion and sampling theorem, we aim to create sine waves, rectangular waves, etc. using MATLAB and to be able to reproduce the waveform as sound.

9. Representation of sound signal (2) Frequency domain representation, Fourier transform
Goal: We aim to understand the principle that the signal in the time domain can be transformed into the signal in the frequency domain by the Fourier transform from the viewpoint of the linear combination of vectors and the calculation of the components by inner product. Also, using MATLAB, we aim to be able to calculate Fourier coefficients and output them to graph by multiplying time waveform vector by DFT matrix.

10. Representation of sound signal (3) Time frequency domain representation, short time Fourier transform, spectrogram
Goal: We aim to understand the principle that spectrogram can be calculated by short time Fourier transform (STFT), and to be able to outline relation of window function and time width and frequency resolution. In addition, we aim to be able to calculate spectrograms actually using MATLAB and display them as image figures.

11. Representation of acoustic signal (4) Analytic signal representation, Hilbert transform, instantaneous frequency, envelope
Goal: We aim to be able to calculate an analytic signal from a real-time signal using MATLAB and to obtain the instantaneous frequency and envelope of the original signal by calculation. We also aim to understand the meaning of Hilbert transform.

12. Representation of transfer characteristic (1) Impulse response, convolution, transfer function
Goal: We aim to be able to prove that the definition of the linear system, superposition, impulse response, convolution, etc. are understood and that it is possible to actually calculate the convolution and can calculate the output signal from the input signal and the impulse response. In addition, we aim to add reverberation by actually performing convolution calculation of input signal and impulse response using MATLAB.

13. Representation of transfer characteristic (2) Z conversion, pole-zero model, all-zero model, linear prediction
Goal: We aim to be able to grasp the characteristics of the approximate transfer function from convolution by Z conversion and multiplication in the Z region, inverse system, and pole / zero position on the Z plane. It also aims to understand the principle of linear prediction.

14. Achievement evaluation (final examination)

Evaluate according to the tasks to be presented during class and the scores of intermediate and final examination.

In the 15th session, we will upload the entire comment using KU-LMS.

No designated textbook

Y. Suzuki, et. al., "Introduction for acoustics (in Japanese)", Japan Acoustic Society, CORONA publishing, 2011
M. Tohyama, "Analytic signal and acoustics (in Japanese)", Springer Japan, 2007
S. Iwamiya, "Basic and application of latest sound (in Japanese)", SHUWA SYSTEM, 2011

Monday, 2 time period, Hachioji campus, 02-605

Not applicable

Informatics Program