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Acoustic Pressure Field vs Sound pressure level

Posted Jun 28, 2020, 12:22 p.m. EDT Low-Frequency Electromagnetics, Acoustics & Vibrations, Optimization 2 Replies

Harsh Goel
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What is the difference between Acoustic Pressure Field and Sound Pressure level? I came across a similar question but the answered that it is the same just Pascal to dB but I find my solutions to be wrong using Sound Pressure Level. Please correct me if I am wrong.

2 Replies Last Post Jul 11, 2020, 6:13 a.m. EDT
Ulf Orrenius
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Posted: 4 years ago Jul 4, 2020, 8:03 a.m. EDT

Dear Harsch maybe I do not fully understand your question but the Sound Pressure Level (SPL) is simply : SPL=10*log (p/p_ref)^2 dB, with p_ref being the the reference pressure, typically 10^-12 Pa in air (different p_ref in liquids). SPL is measored in dB (non-dimensional) whereas pressure is measured in Pascal for SI units. Imperial units can be applied of course. Hope this helps. /Ulf

Dear Harsch maybe I do not fully understand your question but the Sound Pressure Level (SPL) is simply : SPL=10*log (p/p_ref)^2 dB, with p_ref being the the reference pressure, typically 10^-12 Pa in air (different p_ref in liquids). SPL is measored in dB (non-dimensional) whereas pressure is measured in Pascal for SI units. Imperial units can be applied of course. Hope this helps. /Ulf
Harsh Goel
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Posted: 4 years ago Jul 11, 2020, 6:13 a.m. EDT

Dear Harsch maybe I do not fully understand your question but the Sound Pressure Level (SPL) is simply : SPL=10*log (p/p_ref)^2 dB, with p_ref being the the reference pressure, typically 10^-12 Pa in air (different p_ref in liquids). SPL is measored in dB (non-dimensional) whereas pressure is measured in Pascal for SI units. Imperial units can be applied of course. Hope this helps. /Ulf

Thanks for the reply, I'll explain you. I am trying to optimize a room low band frequency response. When I measure the acpr.p_t in octave bands then the variation is quite huge, around 20-25dB. But when I just change it to acpr.Lp(Sound Pressure Level) then it gets changed to a target error of around 1-2dB. I am new to Comsol and didn't find a good difference between Total Acoustic Pressure Field(acpr.p_t) and Sound Pressure Level(acpr.Lp) in the user manual as well. What I mean is the that the relative distribution should not change when we change the units. Am I right? I have attanched reference images for both. Please check if you guide me on this.

>Dear Harsch >maybe I do not fully understand your question but the Sound Pressure Level (SPL) is simply : >SPL=10*log (p/p_ref)^2 dB, with p_ref being the the reference pressure, typically 10^-12 Pa in air (different p_ref in liquids). >SPL is measored in dB (non-dimensional) whereas pressure is measured in Pascal for SI units. Imperial units can be applied of course. >Hope this helps. >/Ulf Thanks for the reply, I'll explain you. I am trying to optimize a room low band frequency response. When I measure the acpr.p_t in octave bands then the variation is quite huge, around 20-25dB. But when I just change it to acpr.Lp(Sound Pressure Level) then it gets changed to a target error of around 1-2dB. I am new to Comsol and didn't find a good difference between Total Acoustic Pressure Field(acpr.p_t) and Sound Pressure Level(acpr.Lp) in the user manual as well. What I mean is the that the relative distribution should not change when we change the units. Am I right? I have attanched reference images for both. Please check if you guide me on this.

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