Sound pressure Definition and 27 Threads

I am currently doing a physics experiment to find the frequency-dependent attenuation coefficient (α(ω) )of pvc foam, are there any verified/reliable sources that show the attenuation coefficient α(ω) of pvc foam or materials in general? Best I found is this...

Hello, I am confused as to how to think about sound pressure and the distance from a sound source. Let's assume that a sound wave is omnidirectional and propagating away from a source in a sphere. We have the following two equations: Pressure = Force/Area Intensity = Power/Area Many texts...

Homework Statement Spaker located at 90 feet from a auditorium chair. The sound pressure level at the chair is 70 dB. The first reflection from the roof takes 200ms to get to the chair. What distance does the first reflection travel to get to the chair if the room temperature is 303.15 K? What...

Hello, I have a question that I've been struggling to find an answer to / understand. Probably because my understanding of physics is quite limited :) Before I ask the question, these are the things I take as facts, so please correct me if something is wrong: 1. A speaker in half space...

Homework Statement Hello. I have a problem, which is as follows: A seat in a concert hall is 84 ft from the tympani. The tympanist strikesa single note. The sound pressure level of the direct sound of the note at the seat is measured to be 55 dB. The first reflection from the nearest sidewall...

Hello, excuse me if these happen to be basic questions, but I'm a psychologist/neuroscientist in training without any particular experience in physics, and I am just confronted with a very specific problem. I need to measure the sound pressure experienced inside of an MRI scanner...

Is there a good description or formula regarding how the sound pressure from a constant source depends upon ambient pressure? That is, if I were to conduct an experiment where I put a source and a microphone in a container, and then change the pressure in that container with a pump, assuming...

I am trying to do a calculation using a value of -211dB re uPa/V , are these SI units? i.e. if OCV = -211db re uPa/V and I have RL = 20log(Vrms) - OCV Do I need to convert the OCV to standard units before putting it in the equation? Wiki isn't so clear about this:

How would you go about calculating the sound power and sound pressure given the pressure (as in collisions [force/area]) of the collision, kinetic energy in the collision, velocities of both objects, densities and masses. Is this possible? Is the pressure of the collision equal to the sound...

Homework Statement The sound pressure level is 80db at a distance of 30 meters. What is the dBSPL at 60 meters? Homework Equations My book has provided me the following formula: dBSPL = dBr-20log(di/dr) - but it has not explained what "di" and "dr" are.The Attempt at a Solution I've been...

Hello, I have read that vacuum cleaner makes 70 dBa and earplugs can easily go beyond this. The problem I have is that I can hear my neighbor's vacuum cleaner thru wall easily. But if I set my mp3 player at max (should be around 100dBa according to manufacturer) I can heard this at few...

I didn't follow the template because this is more of a conceptual question that I can't get a clear answer for. I understand that sound intensity varies with 1/r^2 because the total intensity at a point in the wave is constant and if you have spherical propagation then the area of the surface...

Hello, I am trying to measure the sound pressure inside a cabin. I placed 2 microphones to measure it using octave band. For each frequency i have two sound pressures ..is it possible to take the average of them ? for example add the 2 sound pressure for the 2 microphones and divide...

Hi. Is there a formula for calculating SPL? The information I have is Frequency of pitch, dB level of pitch and 0dB as 20uPa. TIA

Homework Statement The band levels for a noise are 70 dB reference 20\muPa at 31.5 Hz and decrease 3 dB for each octave. Find the overall sound pressure level between 31.5 and 8000 Hz and the A-weighted sound pressure level for this frequency range. Homework Equations...

Homework Statement Consider a sound wave in air of density 1.2 kg/m3. The displacement wave has the form s(x,t)=smaxcos(kx-\omegat) where k=8.79rad/m, \omega=3021.6 rad/s and smax=2.51 x 10-7m. Calculate the sound pressure \DeltaP(x,t) of this wave at x=0.282m and t=0.00137s. Answer in units...

How do I calculate sound pressure inside a channel. I have a channel of 40 mmx 40 mm cross sectional area. I have placed a sound source on one of the side wall that resonates at 50 Khz. I know the voltage required to drive the transducer. The transmit voltage response of the transducer is 110...

pressure=p(x,t)=BkAsin(kx-ωt) http://www.physics.unomaha.edu/Sowell/phys2120/Lectures/Sound/Sound.pdf Surely, when loudness-intensity-pressure increases, so does the maximum displacement A of the speaker. Wrong thread title. My question is: Why increasing the maximum molecule...

How to lower sound pressure (i.e. the volume of a sound)?

1a. Determine the Sound Pressure level at a point due to a machine running alone if the measurements at the point with the machine 'on' and 'off' are 94 dB and 90 dB re 20 uPa respectivele b) Consider white noise where P(f) = A for f >= 0. Show that the SPL's corresponding to successive 1/N...

Hi, I am new to this forum and I'm not sure if I have selected the correct area to post this question. If you think I should move it then let me know! As you can see, I have worked out part of the question but I am stuck when it comes to doing the second half. Any help would be appreciated...

Hi, I am trying to determine the validity of a formula I came across... I have not seen it anywhere else and I can't be sure wether it's valid or not... Consider a number of sound pointsources positioned on a line. The soundwaves coming from each sound source are all in phase (at time t =...

Hi all. A very simple question: what is the difference between sound pressure level and sound intensity level? It seems to me that sound presssure level also measure the "energy" since it is p^2, which shall be related to energy... If it is so, it seems that sound pressure level shall be the...

Homework Statement A baby's mouth is a distance of 35.0 cm from her father's ear and a distance of 1.52 m from her mother's ear. Child Sounds <------------0.35m-------->Father X <----------------------------1.52m-----------------> Mother Homework Equations I(Father) =...

Hey all, I've got an audio related question for you guys/gals: I understand the logarithmic relationship to SPL, but would someone help me out with a simple question and post a formula as to how you arrive at an answer? Assuming a start value of 150 decibels, what pressure level would...