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LRSLA · 09-22-2004, 06:50 PM

I knew I was getting long winded.

I use a quest 2900 type 2 logging sound meter.
The meter has the ability to measure two scales at the
same time. I started out with a RS meter for 45$.
These are not really that good for capturing data that
will support your case. My meter is only garunteed to 1db.
SInce you can't calibate the RS meter it is worthless
for issues related to legal issues.

The three traces that I use are LEQ RED and LMAX and LPeak.

In these traces, LMAX and Lpeak are measured at C scale
with LEQ measured at A scale. What I was trying to point out is that
C scale measurements end up around 10dB higher then a C scale taken at
fifty feet from source.

This trace is made up of samples taken once a second.
My feeling is that the C scale represents the real impact of the
boat noise. The A scale really does not fully show the impact of low frequency noise. But, since the regs are set to that standard it still works for enforcement.

4 stroke outboards and most IO have gotten quieter.
The issue with PWC's is that they are out of the water half the time.
This means that the violate noise regs half the time in most cases.

Noise as a whole is something that is normally avoided by manufacturers.

For instance, most car manufacturers go to great lengths to engineer away noise. This is due to the stress that long term exposure to noise places on the human body. Add in Sun, water, and a couple of beers and increased noise on the water can really effect a boaters ability to operate a craft effectively.

09-22-2004, 06:50 PM	#83
LRSLA Junior Member Join Date: Sep 2004 Posts: 19 Thanks: 0 Thanked 1 Time in 1 Post	Leq ????? I knew I was getting long winded. I use a quest 2900 type 2 logging sound meter. The meter has the ability to measure two scales at the same time. I started out with a RS meter for 45$. These are not really that good for capturing data that will support your case. My meter is only garunteed to 1db. SInce you can't calibate the RS meter it is worthless for issues related to legal issues. The three traces that I use are LEQ RED and LMAX and LPeak. In these traces, LMAX and Lpeak are measured at C scale with LEQ measured at A scale. What I was trying to point out is that C scale measurements end up around 10dB higher then a C scale taken at fifty feet from source. This trace is made up of samples taken once a second. My feeling is that the C scale represents the real impact of the boat noise. The A scale really does not fully show the impact of low frequency noise. But, since the regs are set to that standard it still works for enforcement. 4 stroke outboards and most IO have gotten quieter. The issue with PWC's is that they are out of the water half the time. This means that the violate noise regs half the time in most cases. Noise as a whole is something that is normally avoided by manufacturers. For instance, most car manufacturers go to great lengths to engineer away noise. This is due to the stress that long term exposure to noise places on the human body. Add in Sun, water, and a couple of beers and increased noise on the water can really effect a boaters ability to operate a craft effectively.