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Posted: Fri Aug 11, 2006 12:11 am
by lucky
I just played the Song & turned Volume up til meter read 85 DB.
what's the difference between Sine & Pink noise?
What should I use to make Pink noise?
Thanks,
Lucky
Posted: Fri Aug 11, 2006 1:51 am
by HarBal
Most DAWs have the option to generate files with pink noise in them I believe. At least Adobe audition does anyway.
Pink noise is noise in which the power spectral density is proportional to 1 / frequency. When from natural sources it is often referred to as 1/f noise. Because of the 1/f PSD pink noise has the unique property of having equal power in each band of a logarithmically banded spectrum (ie. octave bands for example). That makes it rather pleasant to listen to and is a rough approximation of the PSD for music.
White noise has a constant PSD which means that the power in equal width logarithmic bands goes up poportional to frequency. This makes white noise unpleasant to listen to.
A sine wave has all the energy concentrated at one frequency so if you have equal power sine wave and white noise or pink noise and look at the spectrums, the sine spectrum will stand out like a sore thumb and will be way above the noise spectra. In terms of what you hear, we have a range of hair cells in the basilar in the cochlea that are excited at different frequencies and you can think of it in terms of a rather crude spectrum analyzer. With the pink noise excitation you'll be stimulating a lot of hair cells by a small amount. With the sine wave you'll be stimulating a small number of hair cells (those tuned to the frequency of the sine wave) by a large amount. That is what makes high level sine waves loud and very unconfortable to listen to.
Like I said, you definitely DON'T want to subject yourself to 85dB SPL sine waves cos it will in all likelihood damage your hearing. If not damage it you'll certainly suffer from tone specific temporary threshold shift.
Regards,
Paavo.
Posted: Fri Aug 11, 2006 9:49 am
by lucky
Does my Tascam 2488 generate Pink noise? What do I need if it doesn't?
Lucky
Posted: Fri Aug 11, 2006 12:38 pm
by har-bal
lucky wrote:I just played the Song & turned Volume up til meter read 85 DB.
what's the difference between Sine & Pink noise?
What should I use to make Pink noise?
Thanks,
Lucky
Lucky
Read these articles.
http://studio-central.com/phpbb/viewtop ... highlight=
http://recforums.prosoundweb.com/index. ... #msg_42415
http://gboers.xs4all.nl/daisy/home/g3/139/loudness.html
You should be using a sound level meter to get to the 85dB level.
Cheers
Earle
Posted: Fri Aug 11, 2006 9:11 pm
by lucky
I read those articles. Thanks. I have Tascam 2488, mucho other Sound stuff & Roland DS-90 Monitors {also JBL's & some Cheapies}. Already have a Sound level meter & have adjusted volume level to 85 Db. Extremely Loud! Fatigues ears Quickly.
My question was what do I use to generate Pink Noise?
Right now I'm just crankin' the Song volume and adjusting to 85Db. An above answer said that adjusting Pink noise to 85 Db should be used as it is less fatiguing rather than adjusting volume level to 85 Db.
What do you suggest?
Thanks,
Lucky
Posted: Sat Aug 12, 2006 1:13 am
by Hitmaker
Lucky ,
Pink noise , as suggested by Paavo , is more a calibration tool ... used because it disperses energy equally over the spectrum ( per octave ) ..
More 'real-life' would be the actual mix , with it's unique spectrum , that occupies you at the time ....
My thoughts .. anyhows ...
Posted: Sat Aug 12, 2006 8:02 am
by HarBal
Lucky,
If your meter is suggesting that 85dB SPL is increadibly loud and quickly fatiguing and your using a music source as the input then I'd suggest that your loudness meter isn't calibrated properly. Make sure the meter is measuring unweighted sound pressure level. If it is A-weighted that may well explain why it sounds too loud.
Basically, for your average Hi Fi passive loudspeaker system in a near field listening environment would require less than 1 Watts RMS power input to get 85 dB SPL. My speakers, which are pretty inefficient, would require around 0.5 Watts RMS to get that sort of level. I'd guess (I haven't measured it) that I drive them at around the 0.1W RMS level most of the time, which would correspond to a listening level of around 78dB SPL.
Cheers,
Paavo.
Posted: Sat Aug 12, 2006 10:14 am
by lucky
Your suggesting adjusting the Song volume to 85 DB then?
I'm using a Radio Shack Sound Level Meter. A & C Settings. Instructions recommend using "C". Also has Slow & Fast Response. Set to SLow. Does this sound right?
Thanks,
Lucky
Posted: Sat Aug 12, 2006 10:50 am
by har-bal
lucky wrote:Your suggesting adjusting the Song volume to 85 DB then?
I'm using a Radio Shack Sound Level Meter. A & C Settings. Instructions recommend using "C". Also has Slow & Fast Response. Set to SLow. Does this sound right?
Thanks,
Lucky
Lucky
Here are the settings.
Weighting should be on "A"
Response "Slow"
Turn the dial to 80 and adjust the volume of your music until is between 4 and 6 on the dB meter. Since you have the dial tuned in at 80dB's range you can tune to 85dB.
Cheers
Earle
Posted: Sat Aug 12, 2006 11:41 am
by lucky
Thanks!
Lucky
Posted: Sun Aug 13, 2006 6:19 am
by HarBal
Lucky and Earle,
I'd disagree about setting the weighting to A. For this purpose you should set the it to un-weighted and if the device only has A and C weightings then set it to C. The reason being is that A weighting will dramatically attenuate the bottom end of the spectrum giving an SPL figure that is lower than the true SPL figure.
A-wieghting is designed as an approximate compensation for subjective loudness in trying to determine with device is subjectively noisiest. This is important for quantifying the noise rating of various devices such as vacuum cleaners, chainsaws and the like as the noise spectrum is confined to certain parts of the spectrum so as a consequence one device may be louder than another by virtue of the sound being at a certain frequency. In this case we aren't trying to figure out subjective loudness but absolute SPL so you should be using no weighting or C weighting which is pretty close to no weighting.
Cheers,
Paavo.
Posted: Sun Aug 13, 2006 7:58 am
by har-bal
HarBal wrote:Lucky and Earle,
I'd disagree about setting the weighting to A. For this purpose you should set the it to un-weighted and if the device only has A and C weightings then set it to C. The reason being is that A weighting will dramatically attenuate the bottom end of the spectrum giving an SPL figure that is lower than the true SPL figure.
A-wieghting is designed as an approximate compensation for subjective loudness in trying to determine with device is subjectively noisiest. This is important for quantifying the noise rating of various devices such as vacuum cleaners, chainsaws and the like as the noise spectrum is confined to certain parts of the spectrum so as a consequence one device may be louder than another by virtue of the sound being at a certain frequency. In this case we aren't trying to figure out subjective loudness but absolute SPL so you should be using no weighting or C weighting which is pretty close to no weighting.
Cheers,
Paavo.
My error, that is correct...it is supposed to be on "C".
Cheers
Earle