Volume vs. loudness?
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GanChan

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I have to crank some of my phones higher/lower than others to get the same volume from my receiver, since they vary in efficiency. My question is, does driving a less efficient phone at a higher level cause any more hearing risk than running the more efficient phone at a lower level, even though the perceived result sounds the same?

That's probably a phenomenally dumb question, but when people talk about achieving greater efficiency, say through an amp, it gets me to wondering about the whole efficiency vs. volume vs. loudness thing. So I'm willing to ask dumb questions if my ears are at issue. Is there an acoustician in the house?


For the record, I listen mostly to classical music, and so am not usually interested in blasting my phones beyond moderate levels. But still.
 
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Steve999

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Hey GanChan --

My layman's opinion is equal loudness presents the same risk of hearing damage regardless of the volume setting or efficiency level of the headphone. A high effeciency phone at a low volume setting and a low efficiency phone at a high volume setting will present the same risk of hearing damage if the actual output volume is the same. I'd be astonished to find out otherwise.
 
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GanChan

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That's what I was hoping -- that I could trust my own ears on this one, so to speak, without having to reach for a dB meter or something. (By the way, where could I GET a dB meter?)

My headphone jack is so crappy I have to turn the volume up for all my phones about 30% higher than I do for my loudspeakers....I need an amp, but it would have to be super-cheap....like an off-brand or something.....



P.S. One downside to having nice phones is that I can now hear all the flaws in the original engineering of recordings! Just finished watching Star Trek: The Motion Picture, and remastered soundtrack or not, there's CLIPPING galore on the music track!
 
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gerG

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Hi GanChan.
This is not a dumb question, and you chased out 3 terms that commonly get randomly interchanged.

Technically, efficiency should be the sound level produced per unit of power delivered (typically expressed in mw for headphones). The reason that this term gets mis-applied is that it depends on more than the volume control setting. If I set my volume control at a point, then switch to higher impedence headphones, my amp will be delivering less power to the high impedence phones. If they are not as loud, they are not necessarily less efficient. If they are as loud, they are more efficient (more sound for less power).

Loudness implies actual acoustic levels, and is typically measured in decibels, which is a logarithmic representation of pressure fluctuations. Loudness is a function of power delivered and efficiency. As elluded to above (or maybe just ocluded) delivered power is proportional to voltage (a function of the volume knob) and inversely proportional to impedence (unique to a particular set of phones).

What I am trying to get at is that the volume knob setting on a receiver or IA does not determine either power or sound level by itself. As a limiting case, consider a receiver with no speakers or cans connected. Turn the knob all the way up, and the delivered power is zero! That is because the impedence is zero. Ignore those dancing power meters, they only measure voltage.

What you do need to worry about is the particular amplifier's voltage limit. That is where clipping and distortion will begin to occur. That limit is dependent on the knob setting, and will be consistent regardless of load with a given signal source. You aren't running out of power, just voltage. fwiw this can be fixed with a matching transformer.

Trust your ears to some extent, but we set volume levels based on several factors as well. I am usually listening for a certain level of detail, and want the full spectrum present. If a particular frequency range is weak, I will tend to crank the level up until the missing info is present. If the particular low spot is due to masking noise (say in a car) I may end up at quite high levels without even realizing it. I believe that this is a reason that Etys seem to have a lack of bass: you can listen to them at such a low level that the ear's natural LF rolloff becomes apparent.

Now your last point baffles me. You mean that I am not supposed to crank up classical music? That would explain some of the strange looks that I get at stop lights.

I hope that I have clarified this issue to some extent. If not, please realize that we are having Oktoberfest where I live!

Later
gerG
 
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kerelybonto

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The only time perceived loudness is not effectively proportional to SPL is when ambient noises vary. Obviously a sound at a certain SPL sounds louder when the surroundings are quieter. So as long as you're not pumping up the volume to mask other noises, you're fine.

kerely
 
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pedxing

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Be careful while judging loudness. Kerelybonto is correct about how ambient noises can affect your judgement. Further, human ears are not very good in determining loudness.

Loudness and sensitivity has no correlation as said before. Basically, loudness is the output sound energy coming from the headphones.

Some of the problems I encountered is that some amps are so poor, I have to turn up the volume to hear detail. With a good amp and some isolation, you can hear more details at lower volumes.
 
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GanChan

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Quote:

Originally posted by Greg Freeman
Hi GanChan.

Now your last point baffles me. You mean that I am not supposed to crank up classical music? That would explain some of the strange looks that I get at stop lights.

gerG


I meant that much of what I listen to -- concertos and so forth -- are actually designed to be listened to at the natural level of the instrument itself, without tons of amplification or processing. That, and the dynamic range is quiet as often as it is loud.

Of course, this doesn't mean you can't bang your head to the 1812 Overture....


One trick I have learned from recording/dubbing digital audio is find the loudest moment on the whole recording, adjust your phones' volume to that moment, then keep it there throughout.
 
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kelly

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GanChan
Beware of genre snobbery. The truth is that the average classical concert meets or exceeds the volume levels of most jazz and rock concerts. Worse, because orchestral classical has such a wide dynamic range, you may find yourself reaching a "natural" volume level for quiet sections only to find it very loud in the crescendos. Also, because such a wide variety of instruments are used in orchestra, the most dangerous to your hearing high frequencies are more likely to be present more often.

Inefficient headphones in and of themselves are not more dangerous than efficient headphones but be aware that some of the more popular efficient headphones have a bright tendency -- Grado's current lines especially. That is to say, if you took a Grado SR-325 and a Sennheiser HD600 and set them both to output the same SPL at a midrange frequency and then played music through both, the high frequencies would be louder on the Grado. As I said earlier, it is the high frequencies that are most dangerous to your hearing.
 
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GanChan

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What about a limiter, along the lines of this?

http://www.glensound.co.uk/GS1U-044andGSXH2.htm

Frankly, I can't imagine having my phones up louder than a face-to-face conversation level (70 dB or so), except for short bursts.

I know where I can find an XLR-to-1/4 inch adapter.....
 
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kelly

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GanChan
I have not heard one of these devices but inheritly, I would expect adding it in the chain to reduce the quality of sound from a headphone amplifier.

Alternatively, if you were using a computer as a source, there are plug-ins for WinAmp and the like to normalize the volume and reduce peaks.

If the average you listen to is truly 70db, then you have nothing to worry about. However, I'd be very suspicious of anyone's measurement who claims to regularly listen so low.
 
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GanChan

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Yes, I wish I was more scientific about it myself. What I do is, I adjust the volume of DVDs (I watch a lot of DVDs
) so that the dialogue is at the same level as it would be if someone in my room was talking to me. Of course, there are louder moments scattered throughout the movie, but they are just moments. Another thing I do is take off my headphones during a loud moment and say a few words, to see how close the music is to the level of my own voice.

So now my headphones have me talking to myself.
 
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GanChan

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I finally went and got one of those sound level meters from Radio Shack. I placed the detector against one of my headphone’s drivers and played a sampling of movies and music to check the levels I typically use for those titles. My movie settings seem safe – dialogue averages in the mid-70dB range, with loud yelling and big sound effects peaking around 85. My classical listening was about the same. But I found that my pop/rock levels ran a little too “hot,” averaging in the mid-80s. I know that level is supposed to be safe for several hours, but because it was peaking around 90 I got kind of nervous and turned it down to a lower volume, to which I will learn to adapt. Actually, once my ears got used to the lower level, the album sounded pretty much the same loudness to me as it had before. Ears are wonderful things.

Anyway, this was maybe an extreme reaction, but if a $35 meter buys me peace of mind, that’s a decent bargain. I will check my music and movies from time to time with this thing, just to keep myself honest. And it’s fun to play with.
 
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Steve999

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I've noticed that too... if I turn the volume down I get used to it and it sounds just fine. I try to get in the habit of turning it down a bit rather than up a bit if I'm going to make any adjustment at all.
I have the radio shack sound meter too, for my home stereo and to keep my son away from noises that are too loud... that's a good idea, using the sound meter for the headphones. I think I'll try it.
This is important stuff.
 
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GanChan

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Something I don't quite understand from the Headroom article on loudness levels using headphones:

"Tone controls can rebalance sound to have the same pleasing amplitude spectrum at lower listening levels. The most accurate loudness compensation would dynamically adjust to both frequency and volume. Such dynamic filters are not widely available to consumers. Still, a small amount of equalization (treble and bass boost) can restore naturalness to the sound of headphones, so that listening at safe levels is appealing (or at least, not unappealing). "

My question is, wouldn't "boosting" the bass and treble simply increase the dB output to the same undesirable levels that we want to avoid?
 
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