In order to have any understanding of SPL it is imperative to understand that it is a weighted average of frequencies. A further discussion could be had on which weighting is most appropriate for which purpose, and what measurement techniques are used to obtain these readings in the first place (full space, half space, etc).
Most SPL meters (do a search) offer only A and C weighting. A few offer flat or Z weighting (or in other words, no weighting at all). What is being weighted is the amplitude over frequency.
To feed this topic swerve just a little more in hopes that will get us back on track, Scott, the integral is over time but not over frequency, with the limits of integration determined by the short or long window of fast or slow response. If you were to integrate the SPL (a function of both f and t) over both frequency and time, a single 125 Hz sine wave at 110 dB with silence at all other frequencies would integrate out to something much much lower than 110 dB since all the zeros at all other frequencies would dominate the integral. The "weighting" is actually a frequency specific attenuation that reduces the contributions of low frequencies more in dBA calculations than in dBC calculations, so your 110 dB sine wave at 125 Hz might register as 89 dBA and 109 dBC.Now back to our regularly programmed topic. Antonio, re: your original post, the speaker sensitivity rating is relevant for passive speakers, but in active speakers it is simply one of many internal design parameters. Given the "watts-manship" distortions of marketing departments, it becomes even less meaningful. By the way, soy tremendo fanatico de la musica de Lucrecia.
I have been away on a one day vacation-sorry.The weighting has NOTHING to do with averaging. It is simply a freq response curve (just like you would do with a crossover) that the mic runs through.An SPL meter is really pretty simple. A mic runs through a mic preamp-then through the response filter (A-C-none etc) and that drives a meter (either VU movement or digital readout).There is NO freq averaging going on. So a single louder freq WILL show a louder SPL-because the PRESSURE is louder (ie Sound Pressure Level).If it were average-then a single tone would show no SPL-as the "average" would be the noise floor of the measurement surroundings.
Hi Ivan. Welcome back My understanding of the SPL meter processing is:Mic into preamp, preamp I to A/D, a time window of samples are taken (with the caveat that the number of samples be an even multiple of the sample frequency ... If memory serves). The time series array is passed into the FFT algorithm which returns an array half the length as the original. The frequency attenuation is applied (A,C,none), some type of smoothing algorithm is applied, and the display updated with the result.Based on your experience, it doesn't seem plausible that a simple average is performed for that smoothing routine.I would be interested in knowing more, but it may be that this subject is already really beyond the scope of this thread. I appreciate your discussion.
In this situation I would like to make 2 pure-sound questions:1) In an indoors venue, melodic music, typical audience being between 3 and 15 m from speaker, which SPL (RMS and peak) might they receive? 90-95?
2) I suppose that the answer equally applies to outdoores venue (a garden). But I intuitively think that the same venue outdoors needs more SPL than indoors? Or do it need more watts? Or maybe not at all? In SPL calculators I don't see the indoors-outdoors option
But I intuitively think that the same venue outdoors needs more SPL than indoors? Or do it need more watts? Or maybe not at all? In SPL calculators I don't see the indoors-outdoors option
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