Wednesday, 2 May 2012

Choosing a good pair of headphones/in-ear headphones



So, you want to buy headphones huh?



I think headphones these days are actually becoming more of a fashion statement than a device that helps you listen to audio. Being a commuter on the TTC (also known as "The Rocket") for the past 7 years, I have observed a marked increase in the use of headphones, ear phones and a bunch of other things. One thing that strikes me though is the large amount of people wearing those "beats" by (dr.) Dre headphones. Those may be great for the bass, but for people who wish to buy some "quality" headphones, here are some of my thoughts regarding a few technical aspects you can look at before purchasing a pair of headphones. While nothing beats trying out the headphones, this guide may be of help for people who wish to buy things online.

You can generally find the specs I've described below on the manufacturer's website or by simply by doing a quick search for it on google. Headphones.com is also a great resource for looking up some specs.


Headphone Impedance

One of the things you have to keep in mind about a headphone is that, effectively, it's just like a resistor (something that burns up energy). It takes the energy from the device that powers it and causes some membrane to vibrate in order to produce sound. The lower the resistance, the louder the sound produced by the headphones for the same amount of power. This is a key factor that you have to consider when buying headphones because if you plan to use a handheld device like an iPhone or a mp3 player to listen to music, you're generally going to want a lower resistance, somewhere between 8Ω - 16Ω (Ω = Ohms, a theoretical measure of the resistance). If the resistance is any higher, you'll likely have to resort to using a headphone amplifier that use batteries to get higher noise levels from your headphones. Not that there's anything wrong with using an amplifier, but it's just an extra inconvenience you may have to deal with in order to listen to some music.

Frequency Response

Here's were things start to get a little subjective, but I'm only going to mention the tech details.

So you probably know that headphones work by vibrating a little membrane like thing (called the "driver"), back and forth. However, the ability of that membrane to vibrate really fast or slow depends on what kind. A whistle sound for example, has a high frequency. A drum beat, however, has a low frequency. While listening to music though you want your headphones to produce both sounds equally well. However, that is not always possible to do. Some headphones can produce lower frequency sounds better, while others can produce higher frequency sounds better. The best types are good at both. As such, each headphone type has it's own "frequency response curve". The "flatter" the curve is, generally means that the headphone can produce more frequencies at the same sound level, and therefore produce more sounds.



X-axis is frequency (how fast the speaker is vibrating), Y-axis is gain (how much potential sound the speaker can produce at that frequency)

In the pictures above, the graph at the top is of a headphone that costs $19.99. To the bottom is a headphone that costs $1,945! (yeah, two thousand bucks!). The main difference is that the cheaper headphones can't produce the lower frequencies as well (like drum beats and such), hence the dip in the curve on the left hand side (which means you can barely hear those sounds). The really expensive ones can handle the bass very easily so it's like a "flat line", hence the price!

This spec of the headphone is what allows the headphone to handle the "lows", "mids" and "highs" that audiophiles often talk about. If you're into base, you want the left hand side of the frequency graph to be flat, and above 0 for the y-axis.

Active Noise Cancelling Headphones

Another type of headphones that are catching on these days are ones that work by playing "antisound" (1/2 wavelength out of phase sound waves, if that means anything to you...) so that it cancels out sound from the outside. These are especially handy if you plan to travel on planes or trains, since it's really easy to generate antisound for the low hum of airplane or subway engines. However a couple of caveats you'll need to keep in mind:

  • Not all sounds are actually cancelled. It won't cancel out the sound of babies crying beside you, or people talking loudly, since it's very difficult to generate antisound for these sounds
  • They'll often require batteries, and some may not even work without batteries. Buying new batteries every week/recharging them may become a hassle really fast
  • These headphones are usually very expensive!
Some things you can check for such headphones are their "noise isolation"/elimination curves.

For example, if you are considering the Bose QC15 headphones, you can google for the noise isolation graph for the headphones, and it'll show something like this:


In this case, you want the frequency curve to be as low as possible for all frequencies, as opposed to the frequency response graphs in the previous two pictures above because want to cancel out/block the noise. Noise from airplane engines are somewhere around 70-100 Hz frequency, and the Bose QC15 do a nice job of cancelling it out by dropping the sound level of the engine noise by ~20dB. That's about the same reduction as reducing the sound of car traffic to the level of sound of an average conversation with a friend (yeah, it's hard to picture sound...).

So with noise cancelling/isolating (noise isolating headphones just block out the noise by covering your ears...) headphones, you'll want to check out these curves and try to find the ones that block out the most noise.

One thing you have to remember is that a side effect of this antisound business is that the actual sound that you want to hear will get a little distorted, changing the frequency response curve of the headphones. As such, it's always a trade off, and it's up to you to decide if noise cancellation is more important than you being able to hear a particular part of a song.

Fit and Finish

One final thing that's pretty obvious is how the headphones fit on you. This is something that you'll likely just have to experience on your own by visiting a store or something, and is highly subjective. As well, you probably want it to look cool.


I, however, don't really mind how it looks as long as it sounds good!





Got a question, tip or comment? Send them to beyondteck+question@gmail.com and we'll try to answer it in a blog post!

2 comments:

  1. Why do we need a noise cancelling headsets? It is demand for a well demanded job in “contact center” where the environment is always loud where a large number of calls land every minute. nosie in the back ground has never been good for the business and almost all the contact center mangers understand this point of view. And on the top unlimited hours of its use noise cancelling headsets takes the toll. These noise cancelling headsets are constructed with the lightest and the most durable factual for a daily heavy duty use. These contact center noise cancelling headsets come in both duo / mono styles of speaker.

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  2. A good pair of in-ear headphones offer a great listening experience for you and, if designed right, will mean your fellow commuters can't hear your choice in music. Even if not, you won't be able to hear them complaining.If you're less than impressed with the earphones that were bundled with your Headphones fear not - there are plenty of great alternatives that ensure you won't be suffering in silence.

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