Sorry about this - Something else important to add here. Sound weighting filtering by ISO. Whatever dBA you hear dBC is always louder.
Go here (URL) for full explanation: http://www.sengpielaudio.com/calculator-dba-spl.htm The standard used is ISO, so it applies worldwide - DIN EN 61672-1 2003-10 (DIN-IEC 651) Sorry to go on there folks, but all of this info (4 posts) is relevant to one other. On Dec 4, 1:15 pm, Vic <[email protected]> wrote: > Forgot to add - You can get a note + octave to frequency chart on the > web. > > AND.......If you REALLY want to be smart use this: Diamond Cut > Forensics8 Audio Laboratory. > > It resides here: > > http://www.diamondcut.com/store/index.php?main_page=product_info&cPat... > > Just 1,500 quid gets you the full and latest version. Knock their > socks off! > > On Dec 4, 9:26 am, Vic <[email protected]> wrote: > > > > > Should you want to discover the exact frequency of YOUR hum download > > and install this instrument tuner: > > >www.aptuner.com/cgi-bin/aptuner/apmain.html > > > This tuner detects dBC range modulation and harmonics to one-tenth of > > cent in real time - No recording though, sorry folks. > > > If you can't install it, don't ask me to tell you how. I gave with > > that a long time ago. > > > You may have increase the gain on your mic in Windows. > > > On Dec 3, 5:28 pm, Vic <[email protected]> wrote: > > > > This is why you can hear it and others can’t – You’re a dBC Receptor. > > > Seems like it's regulated by ANSI in the USA - Now there's something > > > to think about folks! Something new to trip "them" up on? > > > > Below is a portion of a document at this website's URL: > > > >www.efsec.wa.gov/bpcogen/DEIS/3.%209%%20Noise.pdf > > > > Humans respond to a sound's frequency or pitch. Environmental noise is > > > composed of many frequencies, each occurring simultaneously at its own > > > sound pressure level. As measured by an electronic sound level meter, > > > frequency weighting combines the overall sound frequency into one > > > sound level. The commonly used frequency weighting for environmental > > > noise is A-weighting, or dBA, which approximates how an average person > > > hears sounds. C-weighting, or dBC, is a measure of the lowest > > > frequencies of sound and vibration. Low frequency noise is usually > > > described as humming or engine-like sounds or a feeling of pressure or > > > vibration. > > > > How 'bout that?! > > > > Impact Criteria for Low Frequency Noise > > > Although the state of Washington regulates low frequency noise through > > > noise regulations using the A-weighted decibel scale, the American > > > National Standards Institute (ANSI) presents recommendations to > > > provide protection from low frequency noise disturbance in Gas Turbine > > > Installation Sound Emissions (ANSI 1989). ANSI recommends limiting > > > noise levels at residences near new gas turbine facilities to 75 to 80 > > > dBC. > > > > As with the original Golder modeling study, the newer Hessler modeling > > > also evaluated low frequency noise levels at the receptors. In > > > general, the new modeling results indicate that low frequency noise > > > from the cogeneration facility (C-weighted sound levels and the lower > > > frequency levels) would be similar to or less than the levels reported > > > by Golder for the original project configuration. Consequently, both > > > studies conclude that low frequency noise would not reach > > > perceptibility thresholds at any of the residential receptors. > > > > The normal threshold of perceptibility for low frequency noise and > > > vibration is 75 to 78 dBC (ANSI 1989). The ANSI recommends C-weighted > > > plant levels should be significantly below 75 dBC at residential > > > receptors. -- You received this message because you are subscribed to the Google Groups "Hum Sufferers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/hum-sufferers?hl=en.
