PHYS 105 1nd Edition Lecture 11 Outline of Last Lecture I. Wave reflection and standing waves Outline of Current Lecture II.Helmholtz Resonator III. Acoustic Impedance IV. Sound Intensity Current LectureHelmholtz Resonator - Resonance frequency of vibrationof =v2 π√AVLov =speed of sound waveoA=area of neckoL=effective length of the neckoV =volume of the resonator- Used to study vibration objects and analyze complex sounds - Resonances in singing rod o Speed of sound wave in a solid v =√Ep-E=elastic modulus-ρ =densityAcoustic Impedance - The ratio of sound pressure to the volume velocity - When sound wave passes through media with different acoustic impedances, the wave energy will reflect backward and transmitted acoustic energy will be reduced - Intrinsic acoustic impedance o Acoustic impedance times the areaZ =ρvThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Sound Intensity - Average sound intensity - Power per unit area -I=p22 ρvop=amplitude of pr essure waveoρ =density of the airov =speed of sound- Harmonic sound at frequency, pressure amplitude is related to displacement amplitude op=2 πfρv s0- Sound powero Power acted on by a sound wave is intensity times the area P=Ix(Area) Unit is
View Full Document