A Question of engineering about Sound. How to calculate in step by step? Thank you.
The octave bands¡¦ Sound pressure levels in dB re 20 £g Pa are:
Hz 57 129 220 420 1K 2K 4K 8K
dB 85 95 90 80 88 70 68 72
What is the overall A-weighted sound pressure level?
To calculate the overall A-weighted sound pressure level, you need to first understand what A-weighting is and how it affects sound measurements. A-weighting is a standardized frequency weighting curve that is commonly used in sound level measurements to approximate the sensitivity of the human ear to different frequencies.
Here are the steps to calculate the overall A-weighted sound pressure level:
Step 1: Determine the A-weighting correction for each octave band
To calculate the A-weighting correction, you need to refer to the A-weighting curve, which provides correction values for different frequencies. The correction values for the given frequencies (Hz) are as follows:
Hz: 57 129 220 420 1K 2K 4K 8K
dB: 85 95 90 80 88 70 68 72
Subtract the correction values associated with each frequency from the corresponding sound pressure levels (dB) to obtain the A-weighted sound pressure levels. For example, the A-weighted sound pressure level at 57 Hz would be 85 dB - A-weighting correction, the A-weighted sound pressure level at 129 Hz would be 95 dB - A-weighting correction, and so on.
Step 2: Calculate the A-weighted sound pressure level for each octave band
Once you have obtained the A-weighted sound pressure level for each octave band, calculate the overall A-weighted sound pressure level. To do this, you will need to determine the sum of the A-weighted sound pressure levels for each octave band.
Step 3: Convert the sum to the overall A-weighted sound pressure level
Convert the sum obtained in step 2 to the overall A-weighted sound pressure level using the following formula:
Overall A-weighted sound pressure level (dB) = 10 * log10(10^(A1/10) + 10^(A2/10) + ... + 10^(An/10))
Where A1, A2,..., An represents the A-weighted sound pressure levels for each octave band.
By following these steps, you should be able to calculate the overall A-weighted sound pressure level using the given octave bands and their sound pressure levels.