monitoring FOH level

[philhjobim]

Hi all, I am looking for a sound level display to show rolling time window dBC on a PC.

 

Priorities are:

1) Essential: Clear display of LEq average dBC with a rolling window anywhere between 1 minute and 5 minutes.

2) Preferred: Rolling LEq, but sequential time periods with history bars / graph okay

3) Preferred: A dBC spl display in parallel and a 10 sec LEq figure to show the trend.

4) Preferred: Affordable cost :-) ie hundreds rather than thousands.

5) Nice to have: Data logging on the PC.

6) Nice to have: Access from multiple PCs, so event manager at reception or me from my office can check levels esp if visiting engineer is working to our sound limits.

 

NOTE: Not important: Absolute calibration or precision. Will be compared to ATB1 record of objective level. Its a guide so the engineer can work to a level. Our sound limits are set to minimise complaints from neighbours, not a licence or legal requirement.

 

Potential signal source: ECM8000 mike and MBox2

 

Thanks

Phil Hicks

Technical Manager

Westbourne Grove Church

[Albatross]

Hi Phil,

At my venue we are about to purchase a Soundear Pro system.

 

http://www.soundear.com/noise-meters/soundear-pro.html

 

It probably is outside your budget but will certainly do all the tasks you're looking for.

[philhjobim]

Hey that soundear stuff is neat - really nice range of products, and if you need multiple sensors, it would be cost effective too.

 

I have taken a look at suggestions from several website threads, and spent a couple of days trawling the web, and thinking about what I am looking for.

 

We want to enable:

- the sound engineer to control the sound level in the venue

- the duty manager to check that the sound engineer (especially visiting engineers) are doing their job, from another room

- the venue manager to have a record of the sound level history, so if any noise level complaints are received, we can examine the cause of the problem.

 

I think there are 3 key points for a system to provide these objectives:

First is the capability for the sound engineer to monitor the sound level with several degrees of averaging so that they can manage the sound to an averaged limit, with a big number display and a guide to the over or underspend on the LEq for the period. I first came across this idea in the form of 10Eazy http://www.10eazy.com/

Jon Burton from the Progidy: http://www.10eazy.com/cases/

Vanguardia, one of the UK festival consultants describes the key values needed as provided by their custom software:

“A laptop display gives the system tech or FOH engineer a large, clear readout of four vital pieces of information: real time sound level, the current changing LEQ, the last minute’s LEQ and the last 15 minutes’ LEQ.”

The variety of averaging contributes to a clear view of how the current sound level is building into the longer term average. This allows the sound engineer to decrease sound levels in the medium term, saving up some LEq “capacity” to use for a louder track or period. If overspend occurs the display guides the engineer on the lower levels needed to recover to the average LEq target.

 

Second is the capability for the data to be seen remotely on other PCs. Logmein or Remote Control allow a one to one view of what is happening, but a really nice option is now available in the form of an IP enabled sound sensor, such as SPLnet:

http://www.splnet.net/PDFFiles/SPLnetds_7.pdf

These clever boxes capture a variety of data and provide it via an SNMP web server, so several PCs can log in and look at weighted SPL, and a variety of LEq’s.

I think there are probably a variety of PC based solutions available at a price from the festival sound services companies. For example Chris Beale Associates, who do network and sound monitoring at Glastonbury and other UK festivals offer a PC server tailored to display data drawn from SPLnet http://www.cba.uk.com/environmental.htm That PC can then provide its data to other PCs.

 

Third is the capability for the system to log data. PCs are the perfect place to store data rather than in the sound meter so there is lots of provision for this from data loggers, but its harder to find as part of a metering application.

 

Conclusion: 10Eazy and SPLnet are nice solutions to all these requirements, but both are very expensive. They have the benefit of fixed calibration but we don’t need that. I was looking for a cheaper version of this type of application. I didn’t particularly want to have a meter with a PC program running from it, though this would be another way of doing the job. I don’t want to have to place an expensive integrating meter in a public area at every event. CESVA have some nice tools if this is the solution you wanted. Probably there are lots of meters that now have good PC linkage - has anyone done a comparison of the new features available on meters ? I have found it very time consuming to compare the offerings on the market, and the websites are often not easy to use.

 

Many of the cheaper solutions are ruled out because I want to monitor dBC. dBA is the commonly preferred measurement for hearing protection, or for assessing the level of noise nuisance at a distance from the venue. In our situation however I am concerned mainly with transmission of bass frequencies. The hall we use was designed to contain 97dBC of sound with a specified spectrum, equivalent to 93dBA. Experience has shown that if we control the level to 93dBA with heavy bass, neighbours (in flats above the hall on steel frame / concrete floor slab construction) will complain. (The entire hall ceiling is triple board on isolated hangers, with 30cm of rockwool between the ceiling skin and the slab above, and heavy sound pads over the lights, it attenuates everything except bass very effectively). If we control the level to 97dBC, the bass leakage is always acceptable. So there are some nice tools which don’t meet the requirement because they are dBA based – heres a nice software spl meter with LEq and history graph: http://www.levelcheck.de/features.php

 

Finally I found what I was looking for here:

http://www.wavecapture.com/RTCapture.html

Cost: 260 Euro/360 USD

With a PC a decent microphone and preamp, calibrate the dB display on the PC to a calibrator value or a precision meter, then RT capture offers PC based:

- precision SLM with variety of displayable values and weighting adjustable on all values

- 6 different LEq values, one with user adjustable period

- big number display with user selection of displayed values, and an under/over LEq target guide bar.

- 1/1 to 1/24 octave RTA

- SPL/LEq log and history graphing

- nicely designed features for adjustable warning thresholds, and automatic log emailling

- sound wave file recording (ogg file)

 

Also if the sound recording and log features aren’t needed the same features are also included in a loudspeaker time domain analyser Tuning Capture.

 

I also noticed that the same piece of software is being sold by SPLnet as a PC data capture tool offered with their network sound sensors.

 

The website has a good demo and documentation. I found many of the other sites lack sufficient detail, don’t make documentation available, or fail to summarise a variety of complex products. I really think the companies should put some more effort into the accessibility of information about their products.

RT Capture is just what I was looking for….. and affordable :-)

[monitoring man]

Also interesting could be the Euterpe software, a free (basic) version can be downloaded at www.SLMsolutions.be

It seems to be very similar to the RT capture of the swedish wavecapture guys but cheaper (200 Euro for Euterpe Plus) and more oriented towards real noise monitoring jobs.

The audio recording option is very advanced here (you can realy specify whan you want to record audio) & you have a nice scheduler where you can specify when & what you want to measure

[Mark Payne]

+1 for Wave Capture's Tuning Capture, now my tool of choice.

 

M