[Narkhisus]

I've got two horribly embarrassing questions that I want to ask. I listen to music using headphone (Philips SHP2000) & my sound card (Creative Audigy Value) that have such a specifications:


Philips SHP2000

Acoustic system: open
Frequency response: 15 - 22 000 Hz
Impedance: 32 ohm
Maximum power input: 500 mW
Sensitivity: 100 dB
Speaker diameter: 40 mm



Creative Blaster Audigy Value

DAC Resolution : 24-bit
Sample Rate : 8 kHz (min) - 96 kHz (max)
Signal-To-Noise Ratio : 100 dB
Voice Poliphony Qty : 64
Audio Modes         Record : 24-bit 96 kHz - 100 dB <br />
                         Playback : 24-bit 96 kHz 5.1 - 100 dB



1.When I listen to a song & move the slider (of volume control) to 25% (in volume control panel), how many dB is the loudness of the music?
2.If dB of a music is a definite number, is there any difference for my ear between listening to a soft pop song (like Jeff Buckley Hallelujah) & a Death metal song. I mean is harsher song more destructive than the softer one when hearing at for example at 60dB?

Thanks in advance

 

[PurpleAngel]

Replace the Audigy value with an Asus Xonar DG
Amazon sometimes sells used ones for around $20.

 

[xnor]

1) Without knowing the max output level of the soundcard and its output impedance we can't even estimate what the sound pressure level (SPL) would be.
 
2) There can be a big difference of loudness between tracks. Death Metal is usually very compressed (low dynamic range, everything is almost equally loud) so it usually will be louder.
 
If you have foobar2000 you can just add both tracks to the playlist - right click - ReplayGain - Scan. The resulting window will show you track gain values.
 
A silent track may show +2 dB and a loud one -10 dB. This means that switching from the silent to the loud track causes a huge change of +12 dB (the difference between the two values) in loudness.

 

[ev13wt]

While some tracks are louder than other, if they dB is the same it will not differ if you listen to death metal or classical music.

Dynamic range can differ as stated above. So if you listen to constant loud music vs. music that is quiet half the time with peaks you can double your listening time at high volume.ä

To get a semi correct measurement, just download a free loudness app, db meter. Place microphone near one of the cups and start the app and the music. Cup your hands to seal off the space between headphone cup and smartphone.

This is only to get a general idea.

 

[Narkhisus]

Thanks PurpleAngel, xnor & ev13wt.
 

The reason of my questions is that a week ago I went to audiometry & the guy said me don't listen to music using headphones at all but I can't. So I decided to listen only in safe volumes (Like 75-85 dB), but I didn't know how I should measure sound loudness. It seems the only way to estimate dB is to use apps & programs as ev13wt said. I will use Audacity to do this.

But in the end I wish to ask another question. Do you know when you listen to a headphone (you say M50) using a portable player (iPod touch), at 50% of maximum volume, how many dB is the sound loudness (I don't want a precise number, I want only to be sure that I'm not passing the 80dB limit)?


Thanks In advance

 

[xnor]

There are at least 3 ways to measure or calculate SPL:
 
1) Using a sound level meter. To seal the headphones' earpads with the meter you need a piece of cardboard or some such.
 
2) Using software. This only works if your microphone and sound card/audio interface are calibrated. Only works out of the box on some smartphones where the developer used the specifications of the hardware. Not necessarily very accurate.
 
3) Measuring output voltage into your headphones using a multimeter. Calculating the rest, see below.
 
 
To your question. Using http://phys.org/news80304823.html at 50% we're down about 30 dB. Assuming the iPod outputs about 1V max we get about 0.03V at 50%.
Sensitivity of the M50 is about 115 dB/V.
 
==> 85 dB SPL max, that is if you play a sine wave. For compressed (e.g. Metal) music you can subtract only a few dB. So 50% seems to be reasonable.

 

[jcx]

I've gotten within ~2 dB of the calculations with the Radio Shack SPL meter and a homemade coupler on good sealing circumaural headphones

 

[Narkhisus]

Thanks xnor & jcx.

@xnor

what a great & helpful reply. I thought 50% of sound volume is much more than 85 dB and so I never passed 30-35% of sound volume.

1.I don't want to take your time, but may I ask you to learn me how to calculate sound loudness (dB) as you did? I mean if for example sensitivity of the M50 was "x" dB/V or I used "x"% of sound volume, how should I calculate dB?
2. When you say "For compressed (e.g. Metal) music you can subtract only a few dB.", you mean compressed music at a definite dB is less loud than a non-compressed one?

Thanks in advance

 

[xnor]

1) First you need the sensitivity. Manufacturers specify it either as dB SPL with 1 mW (milliwatt) or 1 V input. Using the latter is simpler because you have to do less conversion.
You can look at the table in this thread: http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain (3rd column) for sensitivity with 1V of input.
 
Next you need the output voltage of your amp/DAP.
 
If you use the sensitivity @ 1V as suggested above the conversion to/from decibels is simple: 20*log(V) or 10^(dB/20)
(the Windows calculator has both log and 10^x functions if you switch to View - Scientific)
 
Example: 20*log(0.03) = -30 dB, reverse: 10^(-30/20) = 0.03 V
 
Subtract the -30 dB from the sensitivity and you'll get the sound pressure level.
 
Example: 115 - 30 = 85 dB SPL
 
 
To get the output voltage you either have to measure with a multimeter or rely on other people's measurements. Look at the link I posted in my previous reply.
At 100% we're at about 100 dB, at 50% only 70 dB, so the difference is -30 dB. 35% is about another 10 dB lower (=> 75 dB SPL).
 
 
2) The above is based on a single, full-scale sine wave. To put it simple: a clean single tone that is as loud as possible in a digital format.
 
Real music has a lower level on average. For really compressed music you can subtract let's say 6 dB, for some classical tracks 20 dB.
Peaks may still hit the full 85 dB SPL, but the average sound pressure will be lower.

 

[Narkhisus]

I don't know how I should thank you xnor.
 
If I understand your words correctly, so:
 
M50 sensitivity = 115 dB/V
10% = 115-52 = 63 dB SPL
20% = 115-47 = 68 dB SPL
30% = 115-41 = 74 dB SPL
40% = 115-36 = 79 dB SPL
50% = 115-29 = 86 dB SPL
60% = 115-23 = 92 dB SPL
70% = 115-16 = 99 dB SPL
80% = 115-10 = 105 dB SPL
90% = 115-5 = 110 dB SPL
100% = 115-0 = 115 dB SPL

&

Hifiman HE-500 sensitivity = 102 dB/V
10% = 102-52 = 50 dB SPL
20% = 102-47 = 55 dB SPL
30% = 102-41 = 61 dB SPL
40% = 102-36 = 66 dB SPL
50% = 102-29 = 73 dB SPL
60% = 102-23 = 79 dB SPL
70% = 102-16 = 86 dB SPL
80% = 102-10 = 92 dB SPL
90% = 102-5 = 97 dB SPL
100% = 102-0 = 102 dB SPL


Are my calculations right? by the way if a headphone like HE-500 sounds that loud out of iPod (unamped), so why people complain about its low volume (out of iPod)?

 

[ab initio]

Quote:

by the way if a headphone like HE-500 sounds that loud out of iPod (unamped), so why people complain about its low volume (out of iPod)?

 
People like their headphones to be able to reach eardrum-thumping levels during transients --- like in excees of 110 dB SPL. It adds dramatic effect, especially for passages like this one
 
Cheers!

 

[xnor]

... which is likely to cause permanent hearing damage.
 
@Narkhisus: People will complain due to the fact that it is "unamped" (which it is not) and it doesn't reach its potential (which is a fuzzy description and highly subjective, ie not backed up by evidence). The peak of nonsense is reached when they tell you to look for a cheap headphone if you do not want to invest big money into a separate DAC and amp (and possibly even cables).
 
I can see how someone listening to classical music might complain about not enough volume though, but not someone who's listening to compressed stuff.

 

[anetode]

Quote:

The reason of my questions is that a week ago I went to audiometry & the guy said me don't listen to music using headphones at all but I can't. So I decided to listen only in safe volumes (Like 75-85 dB)\

That guy appears to have given you some very generic and not very useful advice. Hearing damage caused by exorbitant headphone listening volumes may be a bad general trend among kids but that's far from a sound basis for condemning resonsible headphone listening. There are a couple of approaches determining a safe listening volume, the simplest being to start out at the quietest setting and slowly step up until you can appreciate all of the soft details of the recording (its dynamic range). If you'd rather stick to specific db figures then try picking up a db meter and testing out situational volume levels - how loud traffic is, how loud is your usual tv listening volume, etc.. Alternately you could try adding a makeshift coupler to headphones (as suggested above) and get a sense for what volume levels you find comfortable. You already have an instinctual sense of volume and these experiments may help you refine it by correlating to specific ranges.

 

[xnor]

Well it's not so easy to judge how loud you listen with headphones compared to speakers, at least that's what I observed. Some people really have difficulties to listen at non-harmful levels, and that is with just a DAP and stock earbuds. (I don't even want to think of what some portable rigs with separate DAC, amp are capable of, though I hope people using those are more responsible.)  That some IEMs are extremely sensitive/efficient doesn't help either.
 
I agree with anetode, but I'm not sure how well slowly stepping up the volume until you can hear all the soft details works out to a safe listening volume.

 

[skamp]

I measured the maximum output of my Rockboxed Clip+ (0dB volume, with a sine wave at 0dBFS) at 0.545Vrms, a far cry from 1Vrms (about 6dB quieter).

Also, according to Wikipedia, the 85dB value is the safe loudness when continually exposed to it for 8 hours at a time. 91dB is safe for 2 hours, which is more than a single disc album (80 minutes max, often about 60 minutes).

Also note that you have to take into account Replaygain (-6 to -12dB attenuation) and a subtractive EQ (like -6dB of additional attenuation across certain frequency bands).

I did some measurements and calculations with my O2/ODAC, Clip+ and Fuze+, and if the specs of my headphones and IEMs are correct, it seems that I am flirting with the hearing damage threshold, as I listen to albums at about 90-93dBrms (for the duration of the album, usually less than the 2 hour mark). That volume matches my listening habit with ear wax in my ears though, which I'm currently getting rid off with a week-long treatment. I'll see what volume I use when the ear wax is completely gone.