Acoustics II

Fundamental knowledge in Mathematics (12th grade).

The Acoustics II curriculum unit integrates a wide range of activities and use of tools that will facilitate the development of useful skills and a more complete view of how any digital signal acquisition and processing system works in the context of research. As an example, we should refer to the use of auditory stimulus simulation programs (e.g. E-Synth – Harmonic Synthesis – version 1.25) and calculation tools (e.g. Excel) to be used in the quantification of acoustic quantities and understanding of the concepts used for this purpose.

The curricular unit comprises:

– 1 theoretical-practical class of 1 hour per week, where the teacher briefly exposes the programmatic contents of the discipline and applies the physical and mathematical concepts to explain practical examples related to the field of Audiology;

– 1 theoretical-practical class of 1 hour per week, where the teacher helps the student to apply the concepts and mechanisms in problem solving, encouraging the student to achieve a greater autonomy;

– 1 practical-laboratory class of 1 hour per week, where students perform with laboratory activities, involving the acquisition and processing of experimental data, relating the thematic contents identified in these activities with the subjects addressed in the theoretical-practical component.

The discipline of Acoustics II, following the UC of Acoustics I, aims to provide the students of the Audiology course with a solid basis with regard to fundamental concepts of Acoustics, so that students can achieve the general objectives inscribed in the training plan of the Audiology course of Coimbra Health School. A special emphasis will be provided on the fundamental acoustic concepts, including the relationship between the characteristics of sound and its perception , the principles of the propagation of sound and acoustics of buildings and the understanding of how they apply to the environment where audiometric tests are carried out and the procedures related to equipment calibration; It is also intended to facilitate the development of problem solving skills and critical spirit, particularly when audiometric information seems inconsistent.

1. Acoustic Impedance (6 hours)

Acoustic impedance – definition; correlation with the transfer function of an acoustic system and its frequency response; applications to Audiology

Acoustic systems – relationship between mechanical and acoustic systems; Helmholtz resonator; complex systems; sound sources and receivers.

2. Physical and physiological aspects of the human auditory perception (15 hours)

Logarithmic scales – definition; the decibel (dB) and references; calculations on scales dB

Sound pressure level – Webner-Fechner law; definition of sound intensity level and sound pressure level; weighted scales; auditory perception of intensity: hearing thresholds, minimum discernible difference, curves of constant sensitivity, hearing level and range of headphones

Sense of pitch – relationship between pitch and frequency; scales Mel and Bark; critical bands and masking.

3. Propagation of sound and acoustics of buildings: inverse distance square law, reflection, refraction, diffraction, reverberation and Sabine’s formula and absorption coefficients. Sound fields. Inner acoustic conditioning.  (12 Hours)

4. Sound radiation: monopoles, dipoles and quadripoles; Radiation efficiency and directionality. (3 Hours)

5. Noise: noise types, noise measurement, regulations about noise at the workplace (6 h)

NAO