Lecture 1 acoustics Flashcards
What is the definition of the mechanical waves ?
Mechanical waves are oscillations of matter particles that propagate
transferring energy
What form may take the mechanical waves ?
MW may take a form of an elastic deformation or of a variation of pressure
Sound propagation
The sound propagation occurs in elastic media only
The sound is mechanical wave
True
A sound can be transmitted through an elastic media only
True
The sound transfers energy but not mass
True
Longitudinal waves is typical to…
Επιμηκή μηχανικα κυματα
Gasses and liquids
Transverse waves are typical to…
Εγκαρσια μηχανικα κυματα
Solids
Physical characteristics of the sound
Intensity
Pressure
Velocity
Wavelength
Frequency/ Period
Phase
Accoustic spectrum (Ακουστικό φάσμα)
Accoustic impedance (Ακουστική αντίσταση)
What is the formula and the measure unit of sound intensity I ? (ένταση)
I=E/t.s
Measure unit: W/m2
What is the formula of the sound pressure ?
Pressure changes during sound passage:
P=ΔΡsinφ added to atmospheric Patm
What is the measure unit of frequency?
H=Hertz(Hz)=1(rep/s)
What is the measure unit of period and what is the formula ?
M.U=(sec) Formula=T=1/f
What is the relationship between the period and the frequency?
They are inversely(αντιστροφως αναλογα)
What are the relations of sound velocity?
Relations:
Density/Pressure (πυκνοτητα)
Temperature
Humitidy (υγρασια)
