This document can be regarded as an extensive summary of the lectures given for the course Architectural Acoustics. Besides, it contains some definitions of the Kutruff (Acoustics - an Introduction) book that is part of this course.
KUTRUFF CHAPTER 7 DIFFRACTION AND SCATTERING ...........................................................................................22
BUILDING ACOUSTICS ..................................................................................................................................................23
LECTURE B.1 ............................................................................................................................................................23
Sound waves in isotropic solids ..........................................................................................................................23
Sound waves in unbounded solids ......................................................................................................................23
Reflec�on and refrac�on, Rayleigh wave ...........................................................................................................25
Wave in plates and bars ......................................................................................................................................26
LECTURE B.2 ............................................................................................................................................................29
Building acous�cs................................................................................................................................................29
Characteriza�on and measurement ...................................................................................................................29
Single leaf par��ons ...........................................................................................................................................30
Double leaf par��ons .........................................................................................................................................31
KUTRUFF CHAPTER 10 SOUND WAVES IN ISOTROPIC SOLIDS ................................................................................32
KUTRUFF CHAPTER 14 BUILDING ACOUSTICS .........................................................................................................33
LECTURE B.3 ............................................................................................................................................................33
Sound reduc�on index combining mul�ple surfaces..........................................................................................33
Flanking sound transmission ...............................................................................................................................34
ROOM ACOUSTICS .......................................................................................................................................................36
LECTURE R.1 ............................................................................................................................................................36
Introduc�on ........................................................................................................................................................36
Acous�cs design ..................................................................................................................................................36
LECTURE R.2 CONCERT HALL ...................................................................................................................................37
Impulse response measurement ........................................................................................................................37
Roomacous�c parameters ..................................................................................................................................38
Speech transmission index..................................................................................................................................40
LECTURE R.3 ............................................................................................................................................................41
Room acous�cs in small rooms ...........................................................................................................................41
Experiment: how do room modes behave in the tu labaratory?........................................................................42
Sound absorp�on ................................................................................................................................................42
KUTRUFF CHAPTER 9 SOUND IN CLOSED SPACES ...................................................................................................44
KUTRUFF CHAPTER 13 ROOM ACOUSTICS ..............................................................................................................44
2
, 7LS8M0 Architectural Acous�cs
FUNDAMENTALS OF ACOUSTICS
LECTURE F.1
HARMONIC MOTION
Harmonic mo�on = periodic mo�on with the same amplitude (e.g. mass-spring system).
Cosine func�on harmonic.
TIME AVERAGED SIGNAL
Integrate harmonic mo�on over �me. The displacement is squared, otherwise we would get just 0.
t0 = sufficiently long �me interval.
COMPLEX NUMBERS
The displacement s(t) can be writen as a complex number, with ‘e’ = complex exponen�al.
The physical signal is the real value of the complex signal:
𝑠𝑠̂ = |s| = amplitude of the signal
ωt + ϕ = phase of the signal
Real part = the projec�on on the x
axis = 𝑠𝑠̂ ∙ cos (ωt + φ)
Imaginary part = the projec�on on
the y axis = 𝑠𝑠̂ ∙ sin (ωt + φ)
3
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