Scale sound ?

[trainforfun]

I am not sure but if you use a decibel meter to check a real GP35 at 160' , do you think we could use that measure to adjust the motor sound of an N scale locomotive at 1' using the same decibel meter ?
I have a tendency to say yes , what you all think ?

[wazzou]

I am not sure but if you use a decibel meter to check a real GP35 at 160' , do you think we could use that measure to adjust the motor sound of an N scale locomotive at 1' using the same decibel meter ?
I have a tendency to say yes , what you all think ?

Maybe...if you can find an operable, unrebuilt GP35. 

[thomasjmdavis]

The answer is "yes, but..."  There is no reason that the meter wouldn't work.  The problem would be that you would then also experience virtually the same sound level at 3' (480 scale feet) or 5' (800 scale feet) or 7'- where it would seem much too loud.  All the more so, because you are indoors with a lot of reflective surfaces (walls and ceilings, and uncarpeted floors).  Sound doesn't "scale". 

I've spent much of my life managing auditoriums, and I've run my share of audio.  In my last auditorium, while sound would diminish slightly with distance, if the band onstage was producing 105 dB in the front row, at the back of the auditorium, 100+ feet away, we would still register 90-95 dB on the meter.

Let's say that a locomotive at 160' registers 80 dB.  So, in your example, you set your sound card to emit 80 dB (or maybe 80.05 or some such)- to register 80 dB at 1' distance on your meter, at several feet away, you will still be hearing 79 dB (or more).  (Decibels are not a linear scale- 80 dB is 10 times more sound pressure, not 10% more sound pressure).

I am sure we have a few engineers and professors here who can give a more precise explanation.  But for practical purposes, I think the best course is to set sound levels to whatever level you most enjoy, or for operations sessions, at a level low enough that it does not interfere with communications.

[nickelplate759]

Not really.  At best the level would be accurate if you were listening from 1' away, but since your ears are about 6" apart at least one of them will likely be in at the wrong distance.  The frequency balance will not be "accurate", as high frequencies dissipate more rapidly than low frequencies in air - but the air is real 1:1 air, not N-scale air.

Phenomena related to mass (which includes sound, since it's vibrations in the air, which has mass)  don't scale linearly with the dimensions of models, since the actual mass of matter involved isn't scaled down.

If you really wanted "scale sound" as the listener moves around, you'd need a way of dynamically detecting the listener's position relative to the source and use that information continuously adjust the sound level and frequency balance - and then it would only work for one listener at a time.

[peteski]

Louis, I think that you are overthinking this.
Not only as others have mentioned that sound does not scale the same way as physical dimensions, then there are lots of other things which can affect the sound. Things like the layout room's acoustics vs. open air environment when you measured the sound of a 1:1 loco.  Then the dB is not a linear scale, so that could be a problem with your equation. Plus I suspect that if you tried to do what you wrote, the speaker/amplifier in the model would not be able to generate sound that was loud enough to sound like you were standing 160' away from the 1:1 loco.

Then there is a fact that when it comes to human beings, sound level is a very subjective thing.  Something you find as sounding loud enough, someone else might find too quiet or too loud.  Bottom line is that I would recommend forgetting the dB meter and adjust the sound to what you find most pleasing.  Just because you have a cool app on your smart phone (I assume that is your dB meter) that doesn't mean that it has to rule your world. 

[randgust]

My feeling is that air horns, bells, etc. are pretty good now in the high-medium acoustic range, but the constant noise kinda gets to me.   In N I still like to hear things like wheels derailing....before things hit the floor.    I have a small layout, and various digital sound generators built from Ardino boards and MP3 files.   But what is so elusive is the deep rumble of a diesel, the kind of noise that used to vibrate my house windows when a heavy coal drag was working uphill behind 3 SD40's in run 8 on Conrail, and still does here when B&P charges out of town behind 3 GP40's working an uphill grade with a heavy train.   It fills the entire valley with sound.   I've got sub-woofers but even those don't get it.

That B&P train is almost half a mile away from my house, and it's still loud enough for me to hear it notch up through the throttles.   I admit I love to hear it peg up to 8, blasting for the crossings.   

I've played with volume, not satisfied.

Another great experience was in Flagstaff, AZ in 1992 before they put in the quiet zone.   Any westbound would drift through until both crossing gates dropped, and then just PEG IT to Run 8 for the grade up to the Divide west of town.  It was freakin' awesome, blasting through with the horns, and was shaking the earth to the point that the car alarms at the depot went off.   Glad I didn't live there, but MAN!

[peteski]

Randy, that sounds like you would love the BLI "Sound of Thunder" system.  I OTOH like scaled down sound. I would never expect a gut-shaking bass sound from my 6" model.  Like I mentioned, sound is a very subjective and personal thing.

I'll never forget my gut-shaking diesel sound experience.  Back in the late '80s during a model train show one of our NTRAK club members brought in a diesel sound synthesizer.  It hooked up to the DC throttle track output (to control the diesel rpms) on his engine service facility and the line-level audio output was connected to  his home stereo's amplifier and a large 3-way speaker system with IIRC a 15" woofer!  Yes, he dragged all that equipment to the show.  The show was in the Shriners auditorium which is a rather large venue with high roof.

Of course he had the volume set high enough that you could feel the low-frequency rumble in your stomach. It was loud enough to be clearly audible on the other end of the auditorium.  Since he used the throttle with the sound system to run locomotives back and forth on his module, we were continuously subjected to that sound. Even at idle, the sound was loud.  After a while, we asked him to turn the volume down, but even then, the sound was annoyingly loud. Towards the end of the show he did turn it way down,  but at that point many of us in the club had headaches.  Loud N scale sound? No, thanks!  It was cool for the first 10 minutes, then the attraction wore out quickly.

[trainforfun]

Wow , great answers from all of you , true that an N scale loco sound ( to me at least ) about the same when I am close to it and 6 feet or more away .

Sound locomotive is great at first but after a while it's too much , my preferred sound is when a loco is idling somewhere , with a random hiss .

I have 7 diesels and 3 steamers , that's why I wanted to diminish the motor sound , when they are all moving it's way too much !!!

Thanks a lot , really appreciate your answera !!!

[ednadolski]

Loud N scale sound? No, thanks!  It was cool for the first 10 minutes, then the attraction wore out quickly.

This is true in any scale, and even somehow (JMHO) seems worse coming from a tiny cell-phone speaker.

When I do the layout sound with the subwoofer, I have everything turned way down -- just enough to be there, but not intrusive.

One yardstick -- when the sound is switched off, is it a relief or does it seem that things have gone dead?

Ed

[Bill H]

I operate on one layout where ALL the locos are sound equipped and sometimes up to 15 persons running trains at the same time, in a large basement. Note that there are some view blocks in strategic places.

In general, I cannot hear the prime mover / steam sound of another loco that is 8-10 feet away, but I can hear the horn a bit closer, and the bell if right next to me. In general, I have never heard any complaints about the sound being too loud, nor any complaints about the sounds being too soft. Seems like a good compromise for most operators.

Kind regards,
Bill

[trainforfun]

The answer is "yes, but..."  There is no reason that the meter wouldn't work.  The problem would be that you would then also experience virtually the same sound level at 3' (480 scale feet) or 5' (800 scale feet) or 7'- where it would seem much too loud.  All the more so, because you are indoors with a lot of reflective surfaces (walls and ceilings, and uncarpeted floors).  Sound doesn't "scale". 

I've spent much of my life managing auditoriums, and I've run my share of audio.  In my last auditorium, while sound would diminish slightly with distance, if the band onstage was producing 105 dB in the front row, at the back of the auditorium, 100+ feet away, we would still register 90-95 dB on the meter.

Let's say that a locomotive at 160' registers 80 dB.  So, in your example, you set your sound card to emit 80 dB (or maybe 80.05 or some such)- to register 80 dB at 1' distance on your meter, at several feet away, you will still be hearing 79 dB (or more).  (Decibels are not a linear scale- 80 dB is 10 times more sound pressure, not 10% more sound pressure).

I am sure we have a few engineers and professors here who can give a more precise explanation.  But for practical purposes, I think the best course is to set sound levels to whatever level you most enjoy, or for operations sessions, at a level low enough that it does not interfere with communications.

I understand,  I think I should then measure a loco at 1,600 feet and adjust the model at this level when I am close .
Will see , thanks all !

[Ed Kapuscinski]

My methodology is "programming on the main" and then just showing it until it feels "right".

Sometimes this is hobby is more art than science.

[trainforfun]

My methodology is "programming on the main" and then just showing it until it feels "right".

Sometimes this is hobby is more art than science.

First I never program anymore on the main , because I did a mistake once and programmed all locomotives to the same address ... ( 150 locomotives ... )

I downloaded app , decibelmeter and adjusted all my loco to about 50 decibels for the motor sound  , it's what I think is acceptable to my ear , like you said , but I wanted them about at the same level