Had to do this for an Asian LE and fire LMR radio customer, and the metrics are sometimes referenced as 'psychoacoustics' (we called it psychotic acoustics). And Ken is correct, this is difficult stuff to measure in a consistent and reproducible manner.
Should reference ITUR468, unless the customer is requiring A-weighted data. If you do not want to spend $$$$$ for Bruel & Kjær stuff (such as my employer), you can probably do something (such as my solution with a decent ADC and ARM4 processor board and a very fast uSD, and external spectral analysis code) if you think it is worth > 75 hr of engineering time. There are cheap acoustic instruments available, but sound level measurements, where related to human hearing, are too difficult to be adding equipment problems and uncertainties. www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.468-4-198607-I!!PDF-E.pdf Brian From: Ken Javor [mailto:[email protected]] Sent: Sunday, February 21, 2016 7:25 PM To: [email protected] Subject: Re: [PSES] Audio monitoring for automotive EMC testing I would not rely on listening to the audio signal picked up by a mic as any sort of pass/fail criteria, unless the presence or complete absence of a tone was the actual criterion. Anything having to do with volume or tone is very subjective. If you have an audio signal as a bona fide pass/fail criterion, (such as speaker output of a radio) then it is easy to monitor it on an o'scope or audio spectrum analyzer with some clear pass/fail criterion in terms of amplitude and/or frequency, or maybe THD. If engine speed is the pass/fail criterion, I would most certainly not use the audio byproduct of the exhaust noise or engine noise as a measurement thereof. That should be instrumented by looking at the tach, which is nowadays available via the OBD connector, and in fact that info can be made available via Bluetooth to a remote monitor, and then you have many engine parameters to look at directly without adding any instrumentation to the engine besides what is already there. Ken Javor Phone: (256) 650-5261 ________________________________________ From: Li Di <[email protected]> Reply-To: Li Di <[email protected]> Date: Mon, 22 Feb 2016 10:07:15 +0800 To: <[email protected]> Subject: [PSES] Audio monitoring for automotive EMC testing Hi Sir, During EMS testing on automotive, the audio signals in the cockpit shall be monitored. Generally, a well-protected microphone can be used for monitoring. But this can only monitor the volume or sound intensity of different audio signals such as sound of engine. The evaluation shall be done by the test engineer subjectively. If there is any other way to monitor the audio signals automatically? The quality of sound or audio signal can be analized by certain equipment or device technically to avoid the man-made error subjectively. If someone has experience on automotive EMS testing, please advice. Thank you very much. Best regards, ________________________________________ Li Di - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
