What is sound? โฆ Soundย isย aย mechanicalย waveย producedย byย vibrationsย thatย travelย throughย aย medium,ย suchย asย air,ย water,ย orย aย solid. waves What is a wave? โฆ Aย waveย isย aย disturbanceย thatย transfersย energyย fromย oneย locationย toย another. harmonic waves For a sinusoidal sound wave traveling in the positive (x)-direction: p(x,t)=pmcosโก(ฯtโkx+ฯ)p(x,t)=p_m\cos(\omega t-kx+\phi)
Theseย areย threeย ofย theย mostย importantย conceptsย inย acoustics.ย Soundย pressure,ย soundย intensity,ย andย soundย powerย areย related,ย butย theyย measureย threeย differentย physicalย things. Sound power Sound power, PP is the total acoustic energy emitted by a source every second (1/s). For example, a loudspeaker might emit 1 watt of actual acoustic power. Sound intensity A vector quantity. Sound pressures A scalar quantity.
Engineering acoustics relies on core fundamental metrics and equations to quantify sound pressure, energy, impedance, and room characteristics. spl, sound pressure level reference acoustic pressure by medium Medium Reference Pressure, prefp_{ref} in ozf/in2 or osi Air 46.4 billionths Freshwater 2.32 billionths Seawater 2.32 billionths Sound Source SPL (dB) RMS acoustic pressure (osi) 140 130 120…
The linear acoustic wave equation explains the propagation of small-amplitude sound pressure waves, pp, through a homogeneous, isotropic, and adiabatic fluid medium. Recall that a medium is just a material through which sound travels. Sound requires a material medium because it propagates through mechanical disturbances of matter. As we recall, acoustic pressure refers to the…