What’s the best way to block the sound of a voice?

Atif asked:

My neighbor talks loudly on the phone and I can’t sleep. What is the best method to block his voice noise?

Great question Atif! There are few things more distracting than hearing someone else’s conversation, and only hearing one side of a phone conversation is even worse. Even if you don’t want it to, your brain is trying to fill in the gaps and that can definitely keep you awake. So what’s the best way to avoid hearing your neighbor? Well, probably the very best way is to try talking to them. Failing that, though, you have three main options: isolation, damping and masking.

Ruído Noise 041113GFDL
So what’s the difference between them and what’s the best option for you? Before we get down to the nitty gritty I think it’s worth a quick reminder of what sound actually is: sound waves are just that–waves. Just like waves in a lake or ocean. Imagine you and a neighbor share a small pond and you like to go swimming every morning. Your neighbor, on the other hand, has a motorboat that they drive around on thier side. The waves the motorboat makes keep hitting you as you try to swim and you want to avoid them.  This is very similar to your situation: your neighbor’s voice is making waves and you want to avoid being hit by them.

Isolation: So one way to avoid feeling the effects of waves in a pond, to use our example, is to build a wall down the center of the pond. As long as there no holes in the wall for the waves to diffract through, you should be able to avoid feeling the effects of the waves. Noise isolation works much the same way. You can use earplugs that are firmly mounted in your ears to form a seal and that should prevent any sound waves from reaching your eardrums, right? Well, not quite. The wrinkle is that sound can travel through solids as well. It’s like we built our wall in our pond out of something flexible, like rubber, instead of something solid, like brick. As waves hit the wall the wall itself will move with the wave and then transmit it to your side. So you may still end up hearing some noises, even with well-fitted headphones.

Techniques: earplugs/earbuds, noise isolating headphone or earbuds, noise-isolating architecture,

Damping: So in our pond example we might imagine doing something that makes it harder for waves to move through the water. If you replaced all the water with molasses or honey, for example, it would take a lot more energy for the sound waves to move through it and they’d dissipate more quickly.

Techniques: acoustic tiles, covering the intervening wall (with a fabric wall-hanging, foam, empty egg cartons, etc.), covering vents, placing a rolled-up towel under any doors, hanging heavy curtains over windows, putting down carpeting

Masking: Another way to avoid noticing our neighbor’s waves is to start making our own waves. We can either make waves that are exactly the same size as our neighbor’s but out of phase (so when theirs are at their highest peak, ours is at our lowest) so they end up cancelling each other out. That’s basically what noise-cancelling headphones do. Or we can make a lot of own waves that all feel enough like our neighbor’s that when thier wave arrives we don’t even notice it. Of course, if the point it to hear no sound that won’t work quite as well. But if the point is to avoid abrupt, distracting changes in sound then this can work quite nicely.

Techniques: Listening to white noise or music, using noise-cancelling headphones or earbuds

So what would I do? Well, first I’d take as many steps as I could to sound-proof my environment. Try to cover as many of the surfaces in your bedroom as in absorbent, ideally fluffy, surfaces as you can. (If it can absorb water it will probably help absorb sound.) Wall hangings, curtains and a throw rug can all help a great deal.

Then you have a couple options for masking. A fan help to provide both a bit of acoustic masking and a nice breeze. Personally, though, I like a white noise machine that gives you some control over the frequency (how high or low the pitch is) and intensity (loudness) of the sounds it makes. That lets you tailor it so that it best masks the sounds that are bothering you. I also prefer the ones with the fans rather than those that loop recorded sounds, since I often find the loop jarring. If you don’t want to or can’t buy one, though, myNoise has a number of free generators that let you tailor the frequency and intensity of a variety of sounds and don’t have annoying loops. (There are a bunch of additional features available that you can access for a small donation as well.)

If you can wear earbuds in bed, try playing a non-distracting noise at around 200-1000 Hertz, which will cover a lot of the speech sounds you can’t easily dampen. Make sure your earbuds are well-fitted in the ear canal so that as much noise is isolated as possible. In addition, limiting the amount of exposed hard surface on them will also increase noise isolation. You can knit little cozies, try to find earbuds with a nice thick silicon/rubber coating or even try coating your own.

By using many different strategies together you can really reduce unwanted noises. I hope this helps and good luck!


Which are better, earphones or headphones?

As a phonetician, it’s part of my job to listen to sounds very closely. Plus, I like to listen to music while I work, enjoy listening to radio dramas and use a headset to chat with my guildies while I’m gaming.  As a result, I spend a lot of time with things on/in my ears. And, because of my background, I’m also fairly well informed about the acoustic properties of  earphones and headphones and how they interact with anatomy. All of which helps me answer the question: which is better? Or, more accurately, what are some of the pros and cons of each? There are a number of factors to consider, including frequency response, noise isolation, noise cancellation and comfort/fit. Before I get into specifics, however, I want to make sure we’re on the same page when we talk about “headphones” and “earphones”.

Earphones: For the purposes of this article, I’m going to use the term “earphone” to refer to devices that are meant to be worn inside the pinna (that’s the fancy term for the part of the ear you can actually see). These are also referred to as “earbuds”, “buds”, “in-ears”, “canalphones”, “in-ear moniters”, “IEM’s” and “in-ear headphones”. You can see an example of what I’m calling “earphones” below.

IPod Touch 2G Remote Mic
Ooo, so white and shiny and painful.

Headphones: I’m using this term to refer to devices that are not meant to rest in the pinna, whether they go around or on top of the ear. These are also called “earphones”, (apparently) “earspeakers” or, my favorites, “cans”. You can see somewhat antiquated examples of what I’m calling “headphones” below.

Club holds radio dance wearing earphones 1920
I mean, sure, it’s a wonder of modern technology and all, but the fidelity is just so low.

Alright, now that we’ve  cleared that up, let’s get down to brass tacks. (Or, you might say…. bass tacks.)

  1. Frequency response curve: How much distortion do they introduce? In an ideal world, ‘phones should responded equally well to all frequencies (or pitches), without transmitting one frequency rage more loudly than another. This desirable feature is commonly referred to as a “flat” frequency response. That means that the signal you’re getting out is pretty much the same one that was fed in, at all frequency ranges.
    1. Earphones: In general, earphones tend to have a worse frequency response.
    2. Headphones: In general, headphones tend to have better frequency response.
    3. WinnerHeadphones are probably the better choice if you’re really worried about distortion. You should read the specifications of the device you’re interested in, however, since there’s a large amount of variability.
  2. Frequency response: What is their pitch range? This term is sometimes used to refer to the frequency response curve I talked about above and sometimes used to refer to pitch range. I know, I know, it’s confusing. Pitch range is usually expressed as the lowest sound the ‘phones can transmit followed by the highest. Most devices on the market today can pretty much play anything between 20 and 20k Hz. (You can see what that sounds like here. Notice how it sounds loudest around 300Hz? That’s an artifact of your hearing, not the video. Humans are really good at hearing sounds around 300Hz which [not coincidentally] is about where the human voice hangs out.)
    1. Earphones: Earphones tend to have a smaller pitch range than headphones. Of course, there are always exceptions.
    2. Headphones: Headphones tend to have a better frequency range than earphones.
    3. Winner: In general, headphones have a better frequency range. That said, it’s not really that big of a deal. You can’t really hear very high or very low sounds that well because of the way your hearing system works regardless of how well your ‘phones are delivering the signal. Anything that plays sounds between 20Htz and 20,000Htz should do you just fine.
  3. Noise isolation: How well do they isolate you from sounds other than the ones you’re trying to listen to? More noise isolation is generally better, unless there’s some reason you need to be able to hear environmental sounds as well whatever you’re listening to. Better isolation also means you’re less likely to bother other people with your music.
    1. Earphones:  A properly fitted pair of in-ear earphones will give you the best noise isolation. It makes sense; if you’re wearing them properly they should actually form a complete seal with your ear canal. No sound in, no sound out, excellent isolation.
    2. Headphones: Even really good over-ear headphones won’t form a complete seal around your ear. (Well, ok, maybe if you’re completely bald and you make some creative use of adhesives, but you know what I mean.) As a result, you’re going to get some noise leakage .
    3. Winner: You’ll get the best noise isolation from well-fitting earphones that sit in the ear canal.
  4. Noise cancellation: How well can they correct for atmospheric sounds? So noise cancellation is actually completely different from noise isolation. Noise isolation is something that all ‘phones have. Noise-cancelling ‘phones, on the other hand, actually do some additional signal processing before you get the sound. They “listen” for atmospheric sounds, like an air-conditioner or a car engine. Then they take that waveform, reproduce it and invert it. When they play the inverted waveform along with your music, it exactly cancels out the sound. Which is awesome and space-agey, but isn’t perfect. They only really work with steady background noises. If someone drops a book, they won’t be able to cancel that sudden, sharp noise. They also tend not to work as well with really high-pitched noises.
    1. Earphones: Noise-cancelling earphones tend not be as effective as noise-cancelling headphones until you get to the high end of the market (think $200 plus).
    2. Headphones: Headphones tend to be slightly better at noise-cancellation than earphones of a similar quality, in my experience. This is partly due to the fact that there’s just more room for electronics in headphones.
    3. Winner: Headphones usually have a slight edge here. Of course, really expensive noise-cancelling devices, whether headphones or earphones, usually perform better than their bargain cousins.
  5. Comfort/fit: Is they comfy?
    1. Earphones: So this is where earphones tend to suffer. There is quite a bit of variation in the shape of the cavum conchæ, which is the little bowl shape just outside your ear canal. Earphone manufacturers have to have somewhere to put their magnets and drivers and driver support equipment and it usually ends up in the “head” of the earphone, nestled right in your concha cavum. Which is awesome if it’s a shape that fits your ear. If it’s not, though, it can quickly start to become irritating and eventually downright painful. Personally, this is the main reason I prefer over-ear headphones.
    2. Headphones: A nicely fitted pair of over-ear headphones that covers your whole ear is just incredibly comfortable. Plus, they keep your ears warm! I find on-ear headphones less comfortable in general, but a nice cushy pair can still feel awesome. There are other factors to take into account, though; wearing headphones and glasses with a thick frame can get really uncomfortable really fast.
    3. Winner: While this is clearly a matter of personal preference, I have a strong preference for headphones on this count.

So, for me at least, headphones are the clear winner overall. I find them more comfortable, and they tend to reproduce sound better than earphones. There are instances where I find earphones preferable, though. They’re great for travelling or if I really need an isolated signal. When I’m just sitting at my desk working, though, I reach for headphones 99% of the time.

One final caveat: the sound quality you get out of your ‘phones depends most on what files you’re playing. The best headphones in the world can’t do anything about quantization noise (that’s the noise introduced when you convert analog sound-waves to digital ones) or a background hum in the recording.