SC-04-08 Richard Cabot posted an update in the group SC-04-08 3 weeks ago No folders found. Please create and select folder. Documents Folder Title Following special characters are not supported: \ / ? % * : | " < > Privacy Public All Members My Connections Only Me Cancel Create 000050.html 3 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X216 Pink noise </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X216 Pink noise</H1> <B>John Woodgate</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X216%20Pink%20noise&In-Reply-To=%3CWODYZYDdEU5RFw0S%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] AES-X216 Pink noise">jmw at jmwa.demon.co.uk </A><BR> <I>Tue Jul 16 06:48:29 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000048.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000052.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#50">[ date ]</a> <a href="thread.html#50">[ thread ]</a> <a href="subject.html#50">[ subject ]</a> <a href="author.html#50">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">27FD1913E8D785419E698FD2B26FBB18857B3B at server.pbri.local</A>>, dated Tue, 16 Jul 2013, Ben Kok <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">b.kok at scena-adviseurs.nl</A>> writes: ><i>So, do we need a true a true stochastic noise test signal or is pseudo </I>><i>random noise as good or even preferred? </I> In my opinion, 'pseudo-random noise' (PSRN) is too broad a concept to allow a safe answer to the question. Furthermore, it must be self-evident that a carefully-specified PSRN would be satisfactory. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000048.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000052.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#50">[ date ]</a> <a href="thread.html#50">[ thread ]</a> <a href="subject.html#50">[ subject ]</a> <a href="author.html#50">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000051.html 4 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>John Woodgate</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3C6vEDh5EDQU5RFwzc%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">jmw at jmwa.demon.co.uk </A><BR> <I>Tue Jul 16 07:00:51 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000049.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000053.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#51">[ date ]</a> <a href="thread.html#51">[ thread ]</a> <a href="subject.html#51">[ subject ]</a> <a href="author.html#51">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">27FD1913E8D785419E698FD2B26FBB18857B3C at server.pbri.local</A>>, dated Tue, 16 Jul 2013, Ben Kok <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">b.kok at scena-adviseurs.nl</A>> writes: ><i>For level measurements, SMPTE ST 202:2010 speaks about C weighting and </I>><i>slow reading. </I> Slow reading (S-mode, IEC 61672-1) is nowhere near slow enough for good repeatability. ><i>In A.3.6. temporal averaging is discussed with a recommended averaging </I>><i>time of 20 s. </I> In my opinion, 20 s is not really long enough. It's not too bad if the noise is clipped to a crest factor of 3 but not if there is no significant clipping (crest factor at least 4.5). ><i> </I>><i>I personally would recommend using an integrating sound level meter and </I>><i>measuring LEQ(C) with an integration time somewhere between 10 s and 30 </I>><i>s for maximum accuracy. Integrating class 2 sound level meters are </I>><i>widely available at modest costs. </I> I would recommend 60 s unless there is a problem of availability of meters with that averaging time. This opinion is based on watching twitching mechanical meter pointers. For LCD displays, twitching is even more disconcerting. The standard should probably comment on the type of read-out, because the effects of different displays on the observer are different. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000049.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000053.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#51">[ date ]</a> <a href="thread.html#51">[ thread ]</a> <a href="subject.html#51">[ subject ]</a> <a href="author.html#51">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000052.html 5 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X216 Pink noise </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X216 Pink noise</H1> <B>Thomas Lago</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X216%20Pink%20noise&In-Reply-To=%3CCOL127-DS9EC057433536C0104F361CC600%40phx.gbl%3E" TITLE="[SC-04-08] AES-X216 Pink noise">thomaslago at msn.com </A><BR> <I>Tue Jul 16 07:37:56 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000050.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000054.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#52">[ date ]</a> <a href="thread.html#52">[ thread ]</a> <a href="subject.html#52">[ subject ]</a> <a href="author.html#52">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>Dear All, I have been reading all emails and it seems that there are some questions in regards to what the different generators can and cannot do. I have been teaching many courses on "generators" and designed quite a few and used even more of them for a wide range of advanced testing. Here comes my initial comments: - An MLS (PRBS) or "deterministic" generator could lead to a variance free excitation. This, however, requires a synchronization with the measurements. The chirp is better for audio than the MLS and has a lower crest factor but the "same" "impulse response properties". More needs to be explained and that is why I use exclamation marks. - A true random will enable an LMS estimate of the non-linearities (Least Mean Square). - FRFs are always defined as stationary. The transient part in the differential equations are omitted in that definition. It MUST be an LTI (linear and time invariant) system for the definition to hold. I would like to see some further discussion on excitation signals and why to use them (their properties and impact on the FRF for different systems). For LTI systems the main difference is in crest factor and number of averages needed (if any). I hope that I have managed to grasp the questions and remarks properly. If not, update and correct me. Let me know if I need to explain more. Best regards, Thomas -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of Ben Kok Sent: Tuesday, July 16, 2013 3:40 AM To: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08 at standards.aes.org</A> Subject: [SC-04-08] AES-X216 Pink noise All, SMPTE ST 202:2010 only considers steady state frequency response and level. As such one might question the requirement for a stochastic test signal. If one would use a deterministic test signal - for instance MLS based pseudo random noise - a more stable measurement in a shorter measurement time is achievable. This would not expose any non-linearity in the B-Chain, what a true noise signal with high crest factor might, but that is not within the scope of SMPTE ST 202:2010. So, do we need a true a true stochastic noise test signal or is pseudo random noise as good or even preferred? Ben Kok _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000050.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000054.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#52">[ date ]</a> <a href="thread.html#52">[ thread ]</a> <a href="subject.html#52">[ subject ]</a> <a href="author.html#52">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000053.html 5 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>Thomas Lago</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3CCOL127-DS6490F87DB91A65CB7642ECC600%40phx.gbl%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">thomaslago at msn.com </A><BR> <I>Tue Jul 16 08:05:10 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000051.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000056.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#53">[ date ]</a> <a href="thread.html#53">[ thread ]</a> <a href="subject.html#53">[ subject ]</a> <a href="author.html#53">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>Dear All, This discussion is highly related to the variance in the generator itself but also the DUT (Device Under Test). If the DUT has no variance and the generator (excitation signal) has no variance, one measurement is enough and a very short integration time is needed (more related to the BT product). The crest factor is more related to avoid excitation of possible non-linearities but for a random generator it will also impact integration time. Why use random generators at all? Why is not a chirp recommended? Best regards, Thomas -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of John Woodgate Sent: Tuesday, July 16, 2013 6:01 AM To: Working group on Measurement and equalization of sound systems in rooms Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">27FD1913E8D785419E698FD2B26FBB18857B3C at server.pbri.local</A>>, dated Tue, 16 Jul 2013, Ben Kok <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">b.kok at scena-adviseurs.nl</A>> writes: ><i>For level measurements, SMPTE ST 202:2010 speaks about C weighting and </I>><i>slow reading. </I> Slow reading (S-mode, IEC 61672-1) is nowhere near slow enough for good repeatability. ><i>In A.3.6. temporal averaging is discussed with a recommended averaging </I>><i>time of 20 s. </I> In my opinion, 20 s is not really long enough. It's not too bad if the noise is clipped to a crest factor of 3 but not if there is no significant clipping (crest factor at least 4.5). ><i> </I>><i>I personally would recommend using an integrating sound level meter and </I>><i>measuring LEQ(C) with an integration time somewhere between 10 s and 30 </I>><i>s for maximum accuracy. Integrating class 2 sound level meters are </I>><i>widely available at modest costs. </I> I would recommend 60 s unless there is a problem of availability of meters with that averaging time. This opinion is based on watching twitching mechanical meter pointers. For LCD displays, twitching is even more disconcerting. The standard should probably comment on the type of read-out, because the effects of different displays on the observer are different. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000051.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000056.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#53">[ date ]</a> <a href="thread.html#53">[ thread ]</a> <a href="subject.html#53">[ subject ]</a> <a href="author.html#53">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000054.html 4 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X216 Pink noise </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X216 Pink noise</H1> <B>philip newell</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X216%20Pink%20noise&In-Reply-To=%3CCAEEhAC%3DN_0bc8NdvXuK3Y30ATA80ZkuXb9hC1vHCwpEq6CdKbw%40mail.gmail.com%3E" TITLE="[SC-04-08] AES-X216 Pink noise">philiprnewell at gmail.com </A><BR> <I>Tue Jul 16 11:16:32 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000052.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000055.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#54">[ date ]</a> <a href="thread.html#54">[ thread ]</a> <a href="subject.html#54">[ subject ]</a> <a href="author.html#54">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>Dear Ben, I tend to agree with you. Also, last Friday, I was discussing this subject with Keith Holland, during a visit to the ISVR, last week. It is easier to standardise a pseudo-random signal than a random one. It is common practice to compress pink and white noise to avoid crest factor problems, but that is hard to standardise. It also seems to be a good idea to use established standard noise measurement techniques that have stood the test of time to establish the levels, such as Leq, where possible, Best wishes, Philip On 16 July 2013 12:40, Ben Kok <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">b.kok at scena-adviseurs.nl</A>> wrote: ><i> All, </I>><i> </I>><i> </I>><i> </I>><i> SMPTE ST 202:2010 only considers steady state frequency response and </I>><i> level. As such one might question the requirement for a stochastic test </I>><i> signal. </I>><i> If one would use a deterministic test signal - for instance MLS based </I>><i> pseudo random noise - a more stable measurement in a shorter measurement </I>><i> time is achievable. This would not expose any non-linearity in the </I>><i> B-Chain, what a true noise signal with high crest factor might, but that </I>><i> is not within the scope of SMPTE ST 202:2010. </I>><i> </I>><i> </I>><i> </I>><i> So, do we need a true a true stochastic noise test signal or is pseudo </I>><i> random noise as good or even preferred? </I>><i> </I>><i> </I>><i> </I>><i> </I>><i> </I>><i> </I>><i> </I>><i> Ben Kok </I>><i> </I>><i> _______________________________________________ </I>><i> SC-04-08 mailing list </I>><i> <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> </I>><i> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </I>><i> </I></PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000052.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000055.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#54">[ date ]</a> <a href="thread.html#54">[ thread ]</a> <a href="subject.html#54">[ subject ]</a> <a href="author.html#54">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000055.html 3 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X216 Pink noise </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X216 Pink noise</H1> <B>John Woodgate</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X216%20Pink%20noise&In-Reply-To=%3CYhnrSBPPMY5RFw2T%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] AES-X216 Pink noise">jmw at jmwa.demon.co.uk </A><BR> <I>Tue Jul 16 11:29:51 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000054.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000049.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#55">[ date ]</a> <a href="thread.html#55">[ thread ]</a> <a href="subject.html#55">[ subject ]</a> <a href="author.html#55">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>In message <CAEEhAC=<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">N_0bc8NdvXuK3Y30ATA80ZkuXb9hC1vHCwpEq6CdKbw at mail.gmail.com</A>>, dated Tue, 16 Jul 2013, philip newell <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">philiprnewell at gmail.com</A>> writes: ><i>It is common practice to compress pink and white noise to avoid crest </I>><i>factor problems, but that is hard to standardise. </I> It's also ineffably stupid. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000054.html">[SC-04-08] AES-X216 Pink noise </A></li> <LI>Next message: <A HREF="000049.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#55">[ date ]</a> <a href="thread.html#55">[ thread ]</a> <a href="subject.html#55">[ subject ]</a> <a href="author.html#55">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000056.html 8 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>Brian Long</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3C8DBDC6D514F3F44B99EA56F331381FE1AD2E6142%40mailbox10.lucas.alllucas.com%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">blong at skysound.com </A><BR> <I>Tue Jul 16 11:46:25 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000053.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000057.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#56">[ date ]</a> <a href="thread.html#56">[ thread ]</a> <a href="subject.html#56">[ subject ]</a> <a href="author.html#56">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>Hello All, A few bits to clarify statements in the thread. The actual text from ST 202 that Ben pulled his quote from is as follows: "At least two methods are widely used for temporal averaging: RC-type averaging in the detector circuit of the analyzer, and calculated averaging in an integrating real-time analyzer. With a calculated averaging method, accuracy can be very high if the measurement is adequately long. The minimum averaging time of a conventional real-time analyzer will typically be such that measurements even at low frequencies are readable with an accuracy better than the tolerances of the standard. It is recommended that measurements be time-averaged over a period of not less than 20 s in the lowest frequency bands for accuracy to within ± 1 dB." Also level calibration is not in ST202. Level calibration is dealt with in SMPTE RP 200. I think it would be worth it for members of the group to assemble a list of existing on the market and readily available products that are capable of the processes mentioned in the thread below. Then I can compare that list to a list of tools that are readily in use in the field per a research survey I did of cinema technicians. Finally the SMPTE groups at this time are working to make existing standards more consistent as such we are constrained to pink noise for the moment. I will let Pete Soper speak more to things but there have been significant discussions as to what the pink noise is used and how it should be tailored. Once this work is completed there is the intention to move forward with next generation test stimulus. In fact if one looks at new bits on the market many manufacturers are already moving beyond pink noise. Regards, Brian Long -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of Thomas Lago Sent: Tuesday, July 16, 2013 7:05 AM To: 'Working group on Measurement and equalization of sound systems in rooms' Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements Dear All, This discussion is highly related to the variance in the generator itself but also the DUT (Device Under Test). If the DUT has no variance and the generator (excitation signal) has no variance, one measurement is enough and a very short integration time is needed (more related to the BT product). The crest factor is more related to avoid excitation of possible non-linearities but for a random generator it will also impact integration time. Why use random generators at all? Why is not a chirp recommended? Best regards, Thomas -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of John Woodgate Sent: Tuesday, July 16, 2013 6:01 AM To: Working group on Measurement and equalization of sound systems in rooms Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">27FD1913E8D785419E698FD2B26FBB18857B3C at server.pbri.local</A>>, dated Tue, 16 Jul 2013, Ben Kok <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">b.kok at scena-adviseurs.nl</A>> writes: ><i>For level measurements, SMPTE ST 202:2010 speaks about C weighting and </I>><i>slow reading. </I> Slow reading (S-mode, IEC 61672-1) is nowhere near slow enough for good repeatability. ><i>In A.3.6. temporal averaging is discussed with a recommended averaging </I>><i>time of 20 s. </I> In my opinion, 20 s is not really long enough. It's not too bad if the noise is clipped to a crest factor of 3 but not if there is no significant clipping (crest factor at least 4.5). ><i> </I>><i>I personally would recommend using an integrating sound level meter and </I>><i>measuring LEQ(C) with an integration time somewhere between 10 s and 30 </I>><i>s for maximum accuracy. Integrating class 2 sound level meters are </I>><i>widely available at modest costs. </I> I would recommend 60 s unless there is a problem of availability of meters with that averaging time. This opinion is based on watching twitching mechanical meter pointers. For LCD displays, twitching is even more disconcerting. The standard should probably comment on the type of read-out, because the effects of different displays on the observer are different. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000053.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000057.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#56">[ date ]</a> <a href="thread.html#56">[ thread ]</a> <a href="subject.html#56">[ subject ]</a> <a href="author.html#56">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000057.html 3 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>John Woodgate</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3CejJKyuP3Ba5RFw3B%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">jmw at jmwa.demon.co.uk </A><BR> <I>Tue Jul 16 13:35:19 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000056.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000058.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#57">[ date ]</a> <a href="thread.html#57">[ thread ]</a> <a href="subject.html#57">[ subject ]</a> <a href="author.html#57">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">8DBDC6D514F3F44B99EA56F331381FE1AD2E6142 at mailbox10.lucas.alllucas.com</A>>, dated Tue, 16 Jul 2013, Brian Long <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">blong at skysound.com</A>> writes: ><i> In fact if one looks at new bits on the market many manufacturers are </I>><i>already moving beyond pink noise. </I> That isn't necessarily good news. There is a danger that results with new methods will be compared with results from several different 'flavours' of pink noise, varying in not only *precise* spectrum and crest factor but amplitude-probability distribution. A reference pink noise on CD would be a help, but it can still produce mangled noise from some 'too clever by half' replay units. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000056.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000058.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#57">[ date ]</a> <a href="thread.html#57">[ thread ]</a> <a href="subject.html#57">[ subject ]</a> <a href="author.html#57">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000058.html 4 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>Brian Long</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3C8DBDC6D514F3F44B99EA56F331381FE1AD2E6690%40mailbox10.lucas.alllucas.com%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">blong at skysound.com </A><BR> <I>Tue Jul 16 18:12:30 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000057.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000059.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#58">[ date ]</a> <a href="thread.html#58">[ thread ]</a> <a href="subject.html#58">[ subject ]</a> <a href="author.html#58">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>So all are aware the intended output is: Specification of a noise. Digital files. A D-Cinema package. CD is a pretty useless format given DCinema is 24bit 48kHz at the current time with the possibility to move to 96kHz. Once the specified noise is created and agreed upon the next step is to explore new signals. -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of John Woodgate Sent: Tuesday, July 16, 2013 12:35 PM To: Working group on Measurement and equalization of sound systems in rooms Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">8DBDC6D514F3F44B99EA56F331381FE1AD2E6142 at mailbox10.lucas.alllucas.com</A>>, dated Tue, 16 Jul 2013, Brian Long <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">blong at skysound.com</A>> writes: ><i> In fact if one looks at new bits on the market many manufacturers are </I>><i>already moving beyond pink noise. </I> That isn't necessarily good news. There is a danger that results with new methods will be compared with results from several different 'flavours' of pink noise, varying in not only *precise* spectrum and crest factor but amplitude-probability distribution. A reference pink noise on CD would be a help, but it can still produce mangled noise from some 'too clever by half' replay units. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000057.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000059.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#58">[ date ]</a> <a href="thread.html#58">[ thread ]</a> <a href="subject.html#58">[ subject ]</a> <a href="author.html#58">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 000059.html 7 KB HTML - Click to view Options Copy Download Link <TITLE> [SC-04-08] AES-X215 B-Chain level measurements </TITLE> pre { white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ } <H1>[SC-04-08] AES-X215 B-Chain level measurements</H1> <B>david murphy</B> <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20AES-X215%20B-Chain%20level%20measurements&In-Reply-To=%3CDC98EF6CF2F08F40AA5AA23B3509EDA97386AA8036%40KRIX-DC.Krix.local%3E" TITLE="[SC-04-08] AES-X215 B-Chain level measurements">dmurphy at krix.com.au </A><BR> <I>Tue Jul 16 18:38:48 MDT 2013</I> <P><UL> <LI>Previous message: <A HREF="000058.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000060.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#59">[ date ]</a> <a href="thread.html#59">[ thread ]</a> <a href="subject.html#59">[ subject ]</a> <a href="author.html#59">[ author ]</a> </LI> </UL> <HR> <!--beginarticle--> <PRE>Hi All, May I put my 2 cents in. I believe that we have been talking about full bandwidth pink noise, which I think would have more 'randomness' than if band limited. I notice that in home cinemas the channel alignment signal is a 'mid range' pink noise, to try to minimise differences caused by irregular loudspeaker response. I realise that our cinema systems will have perfectly uniform and consistent frequency responses (I wish!) so band limiting is not necessary for that reason. However one could make a case for band limiting the pink noise to correlate more with the sensitivity (frequency response) of the human ear. In my experience doing listening tests on loudspeakers, to accurately A-B compare slight differences, you have to set the apparent loudness of each loudspeaker to be as close as possible the same on the same type of programme, eg male singing voice, soprano, flute, bass guitar, or whatever. And then if you listen and compare a different programme type you have to reset the levels to be as close as possible on that programme. So I deduce that perceived sound level is dependent on the band of frequencies one is perceiving. Should we consider a band limited pink noise source for level setting? Eg 500Hz to 2kHz, or even an existing signal, the shaped pink noise used for loudspeaker testing (EIA-426, IEC 60268-1)? John Woodgate made a good point about measurement accuracy and consistency, saying that the pink noise must be averaged for a time long enough to get a particular accuracy, so that should be part of the package /specifications. -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of Brian Long Sent: Wednesday, 17 July 2013 9:43 AM To: Working group on Measurement and equalization of sound systems in rooms Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements So all are aware the intended output is: Specification of a noise. Digital files. A D-Cinema package. CD is a pretty useless format given DCinema is 24bit 48kHz at the current time with the possibility to move to 96kHz. Once the specified noise is created and agreed upon the next step is to explore new signals. -----Original Message----- From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of John Woodgate Sent: Tuesday, July 16, 2013 12:35 PM To: Working group on Measurement and equalization of sound systems in rooms Subject: Re: [SC-04-08] AES-X215 B-Chain level measurements In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">8DBDC6D514F3F44B99EA56F331381FE1AD2E6142 at mailbox10.lucas.alllucas.com</A>>, dated Tue, 16 Jul 2013, Brian Long <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">blong at skysound.com</A>> writes: ><i> In fact if one looks at new bits on the market many manufacturers are </I>><i>already moving beyond pink noise. </I> That isn't necessarily good news. There is a danger that results with new methods will be compared with results from several different 'flavours' of pink noise, varying in not only *precise* spectrum and crest factor but amplitude-probability distribution. A reference pink noise on CD would be a help, but it can still produce mangled noise from some 'too clever by half' replay units. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> _______________________________________________ SC-04-08 mailing list <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>> </PRE> <!--endarticle--> <HR> <P><UL> <!--threads--> <LI>Previous message: <A HREF="000058.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI>Next message: <A HREF="000060.html">[SC-04-08] AES-X215 B-Chain level measurements </A></li> <LI> <B>Messages sorted by:</B> <a href="date.html#59">[ date ]</a> <a href="thread.html#59">[ thread ]</a> <a href="subject.html#59">[ subject ]</a> <a href="author.html#59">[ author ]</a> </LI> </UL> <hr> <a href="https://secure.aes.org/mailman/listinfo/sc-04-08">More information about the SC-04-08 mailing list</a><br> Expand 0 Comments Public All Members My Connections Only Me PublicAll MembersMy ConnectionsOnly Me Public All Members My Connections Only Me
