{"id":2110,"date":"2014-07-29T15:19:54","date_gmt":"2014-07-29T13:19:54","guid":{"rendered":"http:\/\/www.tonmeister.ca\/wordpress\/?p=2110"},"modified":"2023-06-22T09:30:19","modified_gmt":"2023-06-22T07:30:19","slug":"bo-tech-how-loud-are-my-headphones","status":"publish","type":"post","link":"http:\/\/www.tonmeister.ca\/wordpress\/2014\/07\/29\/bo-tech-how-loud-are-my-headphones\/","title":{"rendered":"B&#038;O Tech: How loud are my headphones?"},"content":{"rendered":"\n<ul class=\"wp-block-list\">\n<li><strong>#24 in&nbsp;<a style=\"color: #0088cc;\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/category\/bang-olufsen\/\">a series of articles<\/a>&nbsp;about the technology behind&nbsp;<a style=\"color: #0088cc;\" href=\"http:\/\/www.bang-olufsen.com\/\">Bang &amp; Olufsen<\/a>&nbsp;loudspeakers<\/strong><\/li>\n<\/ul>\n\n\n\n<p>As you may already be aware, Bang &amp; Olufsen makes headphones: the <a href=\"http:\/\/www.beoplay.com\/products\/beoplayh6\">BeoPlay H6<\/a>&nbsp;over-ear headphones and the <a href=\"http:\/\/www.beoplay.com\/products\/beoplayh3\">BeoPlay H3<\/a>&nbsp;earbuds.<\/p>\n\n\n\n<p>If you read some reviews of the H6 you&#8217;ll find some reviewers like them very much and say things like &nbsp;\u201c\u2026excellent clarity and weight, well-defined bass and a sense of openness and space unusual in closed-back headphones. The sound is rich, attractive and ever-so-easy to enjoy.\u201d and \u201c\u2026 by no means are these headphones designed only for those wanting a pounding bass-line and an exciting overall balance: as already mentioned the bass extension is impressive, but it\u2019s matched with low-end definition and control that\u2019s just as striking, while a smooth midband and airy, but sweet, treble complete the sonic picture.\u201d (both quotes are from Gramophone Magazine&#8217;s April 2014 issue). However, some other reviewers say things like &#8220;My only objection to the H6s is their volume level is not quite as loud as I normally would expect.&#8221; (A review from an otherwise-satisfied on Amazon.com). And, of course, there are the people whose tastes have been influenced by the unfortunate trend of companies selling headphones with a significantly boosted low-frequency range, and who now believe that all headphones should behave like that. (I sometimes wonder if the same people believe that, if it doesn&#8217;t taste like a Big Mac, it&#8217;s not a good burger&#8230; I also wonder why&nbsp;they don&#8217;t know that it&#8217;s possible to turn up the bass on most playback devices&#8230; But I digress&#8230;)<\/p>\n\n\n\n<p>For this week&#8217;s posting, I&#8217;ll just deal with the first &#8220;complaint&#8221; &#8211; how loud should a pair of headphones be able to play?<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Part 1: Sensitivity<\/h2>\n\n\n\n<p>One of the characteristics of a pair of headphones, like a passive loudspeaker, is its sensitivity. This is basically a measurement of how efficient the headphones are at converting electrical energy into acoustical output (although you should be careful to not confuse &#8220;Sensitivity&#8221; with &#8220;Efficiency&#8221; &#8211; <em>sensitivity<\/em> is a measure of the sound pressure level or SPL output for the voltage at the input whereas <em>efficiency<\/em> is a measure of the&nbsp;SPL output for the power in milliwatts). The higher the sensitivity of the headphones, the louder they will play for the same input voltage.<\/p>\n\n\n\n<p>So, if you have a pair of headphones that are not very sensitive, and you plug them into your smartphone playing a tune at full volume, it might be relatively quiet. By comparison, a pair of very sensitive headphones plugged into the same smartphone playing the same tune at the same volume might be painfully loud. For example,let&#8217;s look at the measured data for three not-very-randomly selected headphones at <a href=\"https:\/\/www.stereophile.com\/content\/innerfidelity-headphone-measurements\">https:\/\/www.stereophile.com\/content\/innerfidelity-headphone-measurements.<\/a><\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td><strong>Brand<\/strong><\/td><td><strong>Model<\/strong><\/td><td><strong>Vrms to produce 90 dB SPL<\/strong><\/td><td><strong>dBV to produce 90 dB SPL<\/strong><\/td><\/tr><tr><td>Sennheiser<\/td><td>HD600<\/td><td>0.230<\/td><td>-12.77<\/td><\/tr><tr><td>Beoplay<\/td><td>H6<\/td><td>0.044<\/td><td>-27.13<\/td><\/tr><tr><td>Etymotic<\/td><td>ER4PT<\/td><td>0.03<\/td><td>-30.46<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>If we do a little math, this means that, for the same input voltage, the Etymotic&#8217;s will be 3.3 dB louder than the H6&#8217;s and the Sennheiser&#8217;s will be 14.4 dB quieter. This is a <em>very<\/em> big difference. (The Etymotic&#8217;s are 7.7 times louder than the Sennheisers!)<\/p>\n\n\n\n<p>So, in other words, different headphones have different sensitivities. Some will be quieter than others &#8211; some will be louder.<\/p>\n\n\n\n<p>Side note: If you want to compare different pairs of headphones for output level, you could either look them up at the <a href=\"https:\/\/www.stereophile.com\/content\/innerfidelity-headphone-measurements\">stereophile.com site I mentioned above<\/a>, or you could compare their data sheet specifications using the Sensitivity to Efficiency converter on&nbsp;<a href=\"http:\/\/www.jensign.com\/S4\/calc.html\">this page<\/a>.<\/p>\n\n\n\n<p>The moral of this first part of the story is that, when someone says &#8220;these headphones are not very loud&#8221; &#8211; the question is &#8220;compared to what?&#8221;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Part 2: The Source<\/h2>\n\n\n\n<p>I guess it goes without saying, but if you want more out of your headphones, the easiest solution is to turn up the volume of your source. The question then is: how much output can your source deliver? This answer also varies greatly from product to product. For example, if I take four\u00a0not-very-randomly selected\u00a0measurements that I did myself, I can see the following maximum output levels for a 500 Hz, \u00a00 dB FS sine tone at maximum volume sent to a 31 ohm load (a resistor pretending to be a pair of headphones):<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td><strong>Brand<\/strong><\/td><td><strong>Model<\/strong><\/td><td><strong>Vrms<\/strong><\/td><td><strong>dBV<\/strong><\/td><\/tr><tr><td>Lenovo<\/td><td>ThinkPad T420<\/td><td>0.317<\/td><td>-9.98<\/td><\/tr><tr><td>Apple<\/td><td>iPhone 3Ds<\/td><td>0.89<\/td><td>-1.01<\/td><\/tr><tr><td>Apple<\/td><td>MacBook Pro<\/td><td>2.085<\/td><td>+6.38<\/td><\/tr><tr><td>Sony<\/td><td>CDP-D500<\/td><td>6.69<\/td><td>+16.51<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>In other words, the Sony is more than 26 dB (or 21 times) louder than the ThinkPad, if we&#8217;re just measuring voltage.&nbsp;This is a&nbsp;<em>very<\/em>&nbsp;big difference.<\/p>\n\n\n\n<p>So, as you can see, turning the volume <a href=\"http:\/\/en.wikipedia.org\/wiki\/Up_to_eleven\">all the way up to 11<\/a> on different product results in <em>very<\/em>&nbsp;different output levels. This is even true if you compare iPod Nano&#8217;s of different generations, for example &#8211; no two products are the same.<\/p>\n\n\n\n<p>The moral of the story here is: if your headphones aren&#8217;t loud enough, it might not be the headphones&#8217; fault.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Part 3: The Details, French&nbsp;Law, and How to Cheat<\/h2>\n\n\n\n<p>So much for the obvious things &#8211; now we&nbsp;are going to get a little ugly.<\/p>\n\n\n\n<p>Let&#8217;s begin the ugliness with a little re-hashing&nbsp;of a previous posting. As I talked about in <a title=\"B&amp;O Tech: What is \u201cLoudness\u201d?\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/2014\/06\/07\/bo-tech-what-is-loudness\/\">this posting<\/a>, your ears behave differently at different listening levels. More specifically, you don&#8217;t hear bass and treble as well when the signal is quiet. The louder it gets, the more flat your &#8220;frequency response&#8221;. This means that, when acoustical consultants are making measurements of quiet things, they usually have to make the microphone signal as &#8220;bad&#8221; as your hearing at low levels. For example, when you&#8217;re measuring air conditioning noise in an office space, you want to make your microphone less sensitive to low frequencies, otherwise you&#8217;ll get a reading of a high noise level when you can&#8217;t actually hear anything. In order to do this, we use something called an &#8220;weighting filter&#8221; which is an attempt to simulate your frequency response. There are many different weighting curves &#8211; but the one we&#8217;ll talk about in this posting is an <a href=\"http:\/\/en.wikipedia.org\/wiki\/A-weighting\">&#8220;A-weighting&#8221; curve<\/a>. This &nbsp;is a filter that attenuates the low and high frequencies and has a small boost in the mid-band &#8211; just like you do at quiet listening levels. The magnitude response of that curve is shown below in Figure 1. At higher levels (like measuring the noise level at the end of a runway while a plane is taking off over your head), you might want to use a different weighting curve like a &#8220;<a href=\"http:\/\/en.wikipedia.org\/wiki\/A-weighting#B-.2C_C-.2C_D-_and_Z-weightings\">C-weighting<\/a>&#8221; filter &#8211; or none at all.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/a_weighting.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/a_weighting.png\" alt=\"The magnitude response of an A-weighting filter.\" class=\"wp-image-2128\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/a_weighting.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/a_weighting-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 1. The magnitude response of an A-weighting filter.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>So, let&#8217;s say that you get enough money on Kickstarter&nbsp;to create&nbsp;the Fly-by-Night Headphone Company and you&#8217;re going to make a flagship pair of headphones that will sweep the world by storm. You do a little&nbsp;research and you start coming across something called &#8220;<a href=\"http:\/\/shop.bsigroup.com\/ProductDetail\/?pid=000000000030281663\">BS EN 50332-1<\/a>&#8221; and &#8220;<a href=\"http:\/\/shop.bsigroup.com\/ProductDetail\/?pid=000000000030281666\">BS EN 50332-2<\/a>&#8220;. Hmmmm&#8230; what are&nbsp;these? They&#8217;re&nbsp;international standards that define how to measure how loudly a pair of headphones plays. The procedure goes something like this:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>get some pink noise<\/li>\n\n\n\n<li>filter it to reduce the bass and the treble so that it has a spectrum that is more like music (the actual filter used for this is quite&nbsp;specific)<\/li>\n\n\n\n<li>reduce its crest factor so your measurement doesn&#8217;t jump around so much (this basically just gets rid of the peaks in the signal)<\/li>\n\n\n\n<li>do a quick check to make sure that, by limiting the crest factor, you haven&#8217;t changed the spectrum beyond the acceptable limits of the test procedure<\/li>\n\n\n\n<li>play the signal through the headphones and measure the sound pressure level using a dummy head<\/li>\n\n\n\n<li>apply an A-weighting to the measurement<\/li>\n\n\n\n<li>calculate how loud it is (averaged over time, just to be sure)<\/li>\n<\/ol>\n\n\n\n<p>So, now you know how loud your headphones can play using a standard measurement procedure. Then you find out that, according to another international standard called <a href=\"http:\/\/shop.bsigroup.com\/ProductDetail\/?pid=000000000030254244\">EN 60065<\/a> or <a href=\"http:\/\/webstore.iec.ch\/preview\/info_iec60950-1%7Bed2.0%7Den_d.pdf\">EN 60950-1<\/a> there are <a href=\"http:\/\/legifrance.gouv.fr\/affichTexte.do?cidTexte=JORFTEXT000027799648&amp;categorieLien=id\">maximum limits to what you&#8217;re permitted to legally sell&#8230; in France&#8230; for now&#8230;<\/a> (Okay, okay, these are European standards, but Europe has more than one country in it, so I think that I can safely call them international&#8230;)<\/p>\n\n\n\n<p>So, you make your headphones, you make them sound like you want them to sound (I&#8217;ll talk about the details of this in a future posting), and then you test them (or have them tested) to see if they&#8217;re legal in France. If not (in other words, if they&#8217;re too sensitive), then you&#8217;ll have to tweak the sensitivity&nbsp;accordingly.<\/p>\n\n\n\n<p>Okay &#8211; that&#8217;s what you have to do &#8211; but let&#8217;s look at that procedure a little more carefully.<\/p>\n\n\n\n<p><strong>Step 1<\/strong> was to get some pink noise. This is nothing special &#8211; you can get or make pink noise pretty easily.<\/p>\n\n\n\n<p><strong>Step 2<\/strong> was to filter the noise so that its spectrum ostensibly better matches the average spectrum of all recorded and transmitted&nbsp;music and speech in the world. The details of this filter are in another international standard called <a href=\"http:\/\/webstore.iec.ch\/webstore\/webstore.nsf\/Artnum_PK\/18750\">IEC 60268-1<\/a>.&nbsp;&nbsp;The people who wrote this step mean well &#8211; there&#8217;s no point in testing your headphones with frequencies that are outside the range of anything you&#8217;ll ever hear in them. However, this means that there is probably some track somewhere that includes something that is not represented by the spectral characteristics of the test signal we&#8217;re using here. For example: Figure 2, below shows the spectral curve of the test signal that you are supposed to send to the headphones for the test.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_filter.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_filter.png\" alt=\"The magnitude response of the filter applied to the pink noise before sending it to the headphones.\" class=\"wp-image-2129\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_filter.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_filter-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 2. The magnitude response of the filter applied to the pink noise before sending it to the headphones.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>Compare that to Figure 3, which shows an analysis of a popular Lady Gaga tune that I use as part of my collection of tunes to make a&nbsp;woofer unhappy. This is a commercially-available track that has not been modified in any way.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/lady_gaga.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/lady_gaga.png\" alt=\"The spectrum of a Lady Gaga tune. Compare this with the noise filter plot from Figure 2 (plotted in red for your convenience).\" class=\"wp-image-2147\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/lady_gaga.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/lady_gaga-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 3. The spectrum of a Lady Gaga tune. Compare this with the noise filter plot from Figure 2 (plotted in red for your convenience).<\/figcaption><\/figure>\n<\/div>\n\n\n<p>As you can see, there is more energy in the music example than there is in the test signal around the 30 &#8211; 60&nbsp;Hz octave&nbsp;&#8211; particularly noticeable due to the relative &#8220;hole&#8221; in the response&nbsp;that ranges between about 70 and 700 Hz.<\/p>\n\n\n\n<p>Of course, if we took LOTS of tunes and analysed them, and averaged their analyses, we&#8217;d find out that the IEC test signal shown in Figure 2&nbsp;is actually not too bad. However, every tune is different from the average in some way.<\/p>\n\n\n\n<p>So, the test signal used in the EN 50332 test is not going to push headphones as hard&nbsp;as&nbsp;some kinds of music (specifically, music that has a lot of bass content),<\/p>\n\n\n\n<p>We&#8217;ll skip <strong>Step 3<\/strong>, <strong>Step 4<\/strong>, and <strong>Step 5<\/strong>.<\/p>\n\n\n\n<p><strong>Step 6<\/strong> is a curiosity. We&#8217;re supposed to take the signal that we recorded coming out of the headphones and apply an A-weighting filter to it. Now, remember from above that an A-weighting filter reduces the low and high frequencies in an effort to simulate your bad hearing characteristics <em>at quiet listening levels<\/em>. However, what we&#8217;re measuring here is how loud the headphones can go. So, there is a bit of a contradiction between&nbsp;the detail of the procedure and what it&#8217;s being used for. However, to be fair, many people mis-use A-weighting filters when they&#8217;re making noise measurements. In fact, you see A-weighted measurements all the time &#8211; regardless of the overall level of the noise that&#8217;s being measured. One possible reason for this is that people want to be able to compare the results from the loud measurements to the results from their quiet ones &#8211; so they apply the same weighting to both &#8211; but that&#8217;s just a guess.<\/p>\n\n\n\n<p>Let&#8217;s, just for a second, consider the impact of combining Steps 2 and 6. Each of the filters in both of these steps reduce the sensitivity of the test to the low and high frequency behaviour of the headphones. If we combine their effects into a single curve, it looks like the one in Figure 4, below.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/combined_filters.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/combined_filters.png\" alt=\"The magnitude response of the combination of the A-weighting filter and the filter applied to the pink noise signal.\" class=\"wp-image-2130\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/combined_filters.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/combined_filters-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 4. The magnitude response of the combination of the A-weighting filter and the filter applied to the pink noise signal.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>At this point, you may be asking &#8220;so what?&#8221; Here&#8217;s what.<\/p>\n\n\n\n<p>Let&#8217;s take two different pairs of headphones and pretend that we measured them using the procedure I described above. The first pair of headphones (we&#8217;ll call it &#8220;Headphone A&#8221;) has a completely flat frequency response +\/- &lt; 0.000001 dB from 20 Hz to 20 kHz. The second pair of headphones has a bass boost such that anything below about 120 Hz has a 20 dB gain applied to it (we&#8217;ll call that&nbsp;&#8220;Headphone B&#8221;). The two unweighted measurements of these two simulated headphones are shown in Figure 5.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"419\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses.png\" alt=\"The magnitude responses of the two simulated headphones. The blue curve is &quot;Headphone A&quot;. The red curve is &quot;Headphone B&quot;.\" class=\"wp-image-2132\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses-300x224.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 5. The magnitude responses of the two simulated headphones. The blue curve is &#8220;Headphone A&#8221;. The red curve is &#8220;Headphone B&#8221;.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>After filtering these measurements with the weighting curves&nbsp;from Steps 2 and 6 (above), the way our measurement system &#8220;hears&#8221; these headphone responses is slightly different &#8211; as you can see in Figure 6, below.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses_en50332.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses_en50332.png\" alt=\"The magnitude responses of the two simulated headphones as &quot;seen&quot; by a EN 50332 measurement. The blue curve is &quot;Headphone A&quot;. The red curve is &quot;Headphone B&quot;.\" class=\"wp-image-2133\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses_en50332.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_responses_en50332-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 6. The magnitude responses of the two simulated headphones as &#8220;seen&#8221; by a EN 50332 measurement. The blue curve is &#8220;Headphone A&#8221;. The red curve is &#8220;Headphone B&#8221;.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>So, what happens when we measure the sound pressure level of the pink noise through these headphones?<\/p>\n\n\n\n<p>Well, if we did the measurements without applying the two weighing curves, but just using good ol&#8217; pink noise and no messin&#8217; around, we&#8217;d see that Headphone B plays&nbsp;13.1&nbsp;dB louder than Headphone A (because of the 20 dB bass boost). However, if we apply the filters from Steps 2 and 6, the measured difference drops to only 0.46&nbsp;dB.<\/p>\n\n\n\n<p>This is interesting, since the standard measurement &#8220;thinks&#8221; that a 20 dB boost in the entire low frequency region corresponds to only a 0.46&nbsp;dB increase in overall level.<\/p>\n\n\n\n<p>Figure 7&nbsp;shows the relationship between the bass boost applied below 120 Hz and&nbsp;the increase in overall level as measured using the EN 50332 standard.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/en50332_vs_120hz_lowshelf.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"420\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/en50332_vs_120hz_lowshelf.png\" alt=\"The relationship between the increase in SPL as measured using the EN 50332 standard vs. the gain of a bass boost applied to the headphones. (filter characteristics are Low shelving, fc=120 Hz, Q=0707)\" class=\"wp-image-2134\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/en50332_vs_120hz_lowshelf.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/en50332_vs_120hz_lowshelf-300x225.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 7. The relationship between the increase in SPL as measured using the EN 50332 standard vs. the gain of a bass boost applied to the headphones. (filter characteristics are Low shelving, fc=120 Hz, Q=0.707)<\/figcaption><\/figure>\n<\/div>\n\n\n<p>So, let&#8217;s go back to you, the CEO of the Fly-by-Night Headphone Company. You want to make your headphones louder, but you also need to obey the law in France. What&#8217;s a sneaky way to do this? Boost the bass! As you saw above, you can crank up the bass by 20 dB and the regulators will only see a 0.46&nbsp;dB change in output level. You can <em>totally<\/em> get away with that one! Some people might complain that you have too much bass in your headphones, but hey &#8211; kids love bass. And plus, your competitors will get complaints about how quiet their headphones are compared to yours. All&nbsp;because people listening to <a href=\"https:\/\/www.youtube.com\/watch?v=mScdJURKGWM#t=15\">children&#8217;s records<\/a>&nbsp;at high listening levels hear much more bass than the EN 50332 measurement can!<\/p>\n\n\n\n<p>Of course, one other way is to just ignore the law and make the headphones louder by increasing their sensitivity&#8230; but no one would do that because it&#8217;s illegal. In France.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Appendix 1:&nbsp;Listen to your Mother!<\/h2>\n\n\n\n<p>My&nbsp;mother always told me &#8220;Turn down that Walkman! You&#8217;re going to go deaf!&#8221; The question is &#8220;Was my mother right?&#8221; Of course, the answer is &#8220;yes&#8221; &#8211; if you listen to a loud enough sound for a long enough time, you will damage your hearing &#8211; and hearing damage, generally speaking, is permanent. &nbsp;The louder the sound, the less time it takes to cause the damage. The question then is &#8220;how loud and how long?&#8221; The answer is different for everyone, however you can find some recommendations for what&#8217;s probably safe for you at sites that deal with occupational health and safety. For example, <a href=\"http:\/\/www.ccohs.ca\/oshanswers\/phys_agents\/exposure_can.html\">this site<\/a> lists the Canadian recommendations for maximum exposure time limits&nbsp;to noise in the workplace. <a href=\"http:\/\/www.engineeringtoolbox.com\/noise-exposure-level-duration-d_717.html\">This site<\/a> shows a graph for the US recommendations for the same thing &#8211; I&#8217;ve used the formula on that site to make the graph in Figure 8, below.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_exposure.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"419\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_exposure.png\" alt=\"Recommendations for the maximum time of exposure to noise sources according to The National Institute for Occupational Safety and Health (NIOSH) in the USA.\" class=\"wp-image-2136\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_exposure.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/noise_exposure-300x224.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 8. Recommendations for the maximum time of exposure to noise sources according to The National Institute for Occupational Safety and Health (NIOSH) in the USA.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>How do these noise levels compare with what comes out of my headphones? Well, let&#8217;s go back to the numbers I gave in Part 1 and Part 2. If we take the measured maximum output levels of the 4 devices listed in Part 2, and calculate what the output level in dB SPL would be through the measured sensitivities of the headphones listed in Part 1 (assuming that everything else was linear and nothing distorted or clipped or became unhappy &#8211; and ignoring the fact that the headphones do not have the same impedance as the one I used to do the measurements of the 4 devices&#8230; and assuming that the measurements of the headphones&nbsp;are unweighted on that website), then the maximum output level you can get from those devices are shown in Figure 9.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_vs_device_max_outputs.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"419\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_vs_device_max_outputs.png\" alt=\"Calculated maximum output levels in dB SPL for the four devices and three headphones listed in Parts 1 and 2, above.\" class=\"wp-image-2137\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_vs_device_max_outputs.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_vs_device_max_outputs-300x224.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 9. Calculated maximum output levels in dB SPL for the four devices and three headphones listed in Parts 1 and 2, above. Blue is the Etymotic ER4PT, red is the BeoPlay H6, and black is the Sennheiser HD600.<\/figcaption><\/figure>\n<\/div>\n\n\n<p>So, if you take the calculations shown in Figure 8 and compare them to the recommendations shown in Figure 7, then you might&nbsp;reach the conclusion that, if you set your volume to maximum (and your tune is full-band pink noise mastered to a constant level of&nbsp;&nbsp;0 dB FS, and we do a small correction for the A-weighting based on the assumption that the 90 dB SPL headphone measurements listed above are unweighted ), then the maximum recommended time that you should listen to your music, according to the federal government in the USA is as shown in Figure 10.<\/p>\n\n\n<div class=\"wp-block-image thumbnail\">\n<figure class=\"aligncenter\"><a class=\"thumbnail\" href=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_exposure.png\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"419\" src=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_exposure.png\" alt=\"Recommended maximum exposure time for 3 different headphones connected to 4 different sources playing at maximum volume.\" class=\"wp-image-2138\" srcset=\"http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_exposure.png 560w, http:\/\/www.tonmeister.ca\/wordpress\/wp-content\/uploads\/headphone_exposure-300x224.png 300w\" sizes=\"auto, (max-width: 560px) 100vw, 560px\" \/><\/a><figcaption class=\"wp-element-caption\">Fig 10. Recommended maximum exposure time for 3 different headphones connected to 4 different sources playing at maximum volume (based on&nbsp;a large number of assumptions that may or may not be correct).<\/figcaption><\/figure>\n<\/div>\n\n\n<p>So, if I only listen to full-bandwidth pink noise at 0 dB FS at maximum volume on my MacBook Pro over my BeoPlay H6&#8217;s, then the American government thinks that after 0.1486 of a second, I am damaging my hearing.<\/p>\n\n\n\n<p>It seems that my mother was right.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Appendix 2: Why does France care about how loud my headphones are?<\/h2>\n\n\n\n<p>This is an interesting question, the answer to which makes sense to some people, and doesn&#8217;t make any sense at all to other people &#8211; with a likely correlation with&nbsp;your political beliefs and your allegiance to <a href=\"http:\/\/en.wikipedia.org\/wiki\/Tea_Party_movement\">the Destruction&nbsp;of the Tea in Boston<\/a>. The best answer I&#8217;ve read was discussed in <a href=\"http:\/\/www.head-fi.org\/t\/600111\/the-eu-volume-cap-mystery\">this forum<\/a> where one poster very astutely point out that, in France, the state pays for your medical care. So, France&nbsp;has a right to prevent the French&nbsp;from making themselves&nbsp;go deaf by listening to this week&#8217;s top hit on Spotify at (literally) deafening levels. If you live in a place where you have to pay for your own medical care, then you have the right to self-harm and induce your own hearing impairment in order to appreciate the subtle details buried within&nbsp;the latest hip-hop remix of Mr. Achy-Breaky Heart&#8217;s daughter&nbsp;&#8220;singing&#8221; Wrecking Ball while you&#8217;re riding on a bus. In France, you don&#8217;t.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Appendix 3:&nbsp;Additional Reading<\/h2>\n\n\n\n<p><a href=\"http:\/\/www.isvr.co.uk\/labtests\/en50332.htm\">ISVR Consulting&#8217;s page<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/cdn.rohde-schwarz.com\/pws\/dl_downloads\/dl_application\/application_notes\/1ga48\/1GA48_2e.pdf\" data-wplink-edit=\"true\">Rodhe and Schwarz&#8217;s pdf manual<\/a> for running the EN 50332 test on their equipment<\/p>\n","protected":false},"excerpt":{"rendered":"<p>As you may already be aware, Bang &amp; Olufsen makes headphones: the BeoPlay H6&nbsp;over-ear headphones and the BeoPlay H3&nbsp;earbuds. If you read some reviews of the H6 you&#8217;ll find some reviewers like them very much and say things like &nbsp;\u201c\u2026excellent clarity and weight, well-defined bass and a sense of openness and space unusual in closed-back [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[33,4,32,5],"tags":[],"class_list":["post-2110","post","type-post","status-publish","format-standard","hentry","category-acoustics","category-audio","category-bang-olufsen","category-loudspeakers"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p48hIM-y2","_links":{"self":[{"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/posts\/2110","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/comments?post=2110"}],"version-history":[{"count":37,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/posts\/2110\/revisions"}],"predecessor-version":[{"id":7547,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/posts\/2110\/revisions\/7547"}],"wp:attachment":[{"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/media?parent=2110"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/categories?post=2110"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.tonmeister.ca\/wordpress\/wp-json\/wp\/v2\/tags?post=2110"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}