The Sounds of Science

The use of headphones is just one of many aspects of cycling behaviour which generates lively debate; but debate which rarely braves the cold world of data and quantitative study, preferring to inhabit the opinion columns of newspapers and the soundbites of politicians.

Let’s try and move it on a little.

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Signal-to-noise ratio

Much of the discussion of headphones is, sadly, noise. This reached its deafening peak in November 2013, in the wake of a spate of cycling deaths in London. Most notably Boris Johnson publicly decried the use of headphones, even though there was no evidence that they were even in use by any of the deceased, let alone that they had contributed to the collisions.

On the one hand this sparked keen defence of headphones by those who use them, while on the other, the tabloids wheeled out the “zombies” invective, which the Guardian questioned.

So, who’s talking sense?

Is riding with headphones safe?

Often, there’s a simple question we need to answer. But it’s extremely rare that the real world to which they pertain is anything like so simple, even when it might initially appear to be.

So, I think it’s reasonable to translate “is riding with headphones safe?” (and that should really be the subtly but importantly different “does riding with headphones introduce an unacceptable level of danger?”) into the following questions:

  1. Is the rider’s ability to hear external sounds diminished by the presence of headphones and/or the addition of music, speech etc?

  2. Is the resulting loss of ability to hear external sounds of a degree and nature which diminishes their ability to build a dynamic mental picture of the environment and traffic around them?

  3. Is the rider’s concentration diminished by the additional sounds of music, speech etc?

  4. Is the rider’s loss of concentration of a degree and nature which diminishes their ability to concentrate on the environment and traffic around them, and/or their ability to control their own cycle?

  5. Are there any strategies the rider can readily adopt which can sufficiently mitigate any additional risk that may arise from above?

  6. Does familiarity with the use of headphones reduce some or all negative effects that might be experienced at initial use?

Logical consistency

Before we start actually answering those questions, let’s take a quick look at them in terms of their logical implications.

Firstly, one has to consider deaf and partially deaf people. Logically, if one was to argue that the loss of ability to hear sounds was in itself sufficient reason to prohibit cycling with headphones, one would also have to argue that deaf and partially deaf people would have to be banned from cycling.

Secondly, one has to consider cars. Cars have stereos in, and therefore, logically, if one was to argue that loss of concentration through listening to music or speech was in itself sufficient reason to prohibit cycling with headphones, one would also have to argue that car stereos would have to be banned.

So, whilst the questions above are well worth asking, if the answers to them are to be used as arguments in favour of prohibiting the use of headphones there are some pretty hefty logical implications if that argument is to avoid hypocrisy.

But let’s take a pop at answering them anyway.

Experimental data

So, why does the discussion rarely include data and research? Well, it’s partly because there’s not much of it about. But there is some.

Testing ability to hear

Let’s kick off with a paper by de Waard et al, which studied cyclists’ response to an auditory “stop” signal whilst using headphones or mobile phones. It was a small study, of 25 participants, and it found that

Cycle speed was not affected by listening to music, but was reduced in the telephone conditions. In general the response to auditory signals worsened when participants listened to music, in particular when listening with in-earbuds loud auditory stop signals were missed in 68% of the cases. However, when listening with only one standard earbud performance was not affected.

This is hardly surprising: listening to music does reduce the rider’s ability to hear other sounds, and in-ear headphones markedly increase this effect.

Of course, this begs the question: When does one hear an auditory stop signal in real-world road use? I think the use of “a stop signal” carries unfortunate connotations of an on-carriageway directive, and therefore assumptions that there is an inability to respond to “a stop signal”, rather than “an auditory command”. Stop signals are not auditory. They are red lights, white lines, and so on. All visual.

Sadly, this is the most-cited piece of research around, and it’s very often misinterpreted in that exact way.

Comparisons with driving

Some Australians also did a pertinent experiment. It’s not a peer-reviewed paper in a scientific journal, but it is a fairly conscientious test that makes quantitative and qualitative measurements. It found that

A bike rider with ear-bud earphones playing music at a reasonable volume hears much more outside noise than a car driver, even when that driver has no music playing.

A bike rider with in-ear earphones playing music at a reasonable volume hears about the same outside noise as a car driver with no music playing, but more than a car driver playing music.

This reinforces the point made earlier, that if one is to argue for prohibiting cyclists from using headphones, one has to also argue for the prohibiting drivers from using stereos and even windows in order to be logically consistent.

Research overview

The Netherlands’ Institute for Road Safety Research (SWOV) mentioned the de Waard et al paper in a summary of research activities. In it (see p8) they make a notable inference from the experiment:

An experiment in which the participants had to cycle while they were listening to music and using their phones, and were told to stop when they were given an audio signal, indicated that their cycling became less safe than when they did not listen to music.

This is a little disturbing from a research institute, in assuming that some loss of hearing ability (which, crucially, is what de Waard et al tested) is inherently less safe. It’s one of those things that seems obvious, but may or may not be true.

And it’s also the exact type of unfounded inference that I believe de Waard’s “stop signal” test encourages.

On the same page, the authors note that

The use of these types of devices while cycling appears to increase the risk of being involved in a crash.

Where they use the phrase “these types of devices”, they are making a common mistake, which is to gather mobile phones and music players into the same category. They are markedly different: the former require interaction and are widely shown to introduce significant cognitive distraction.

The mistake can be highlighted by the data they cite:

15% of the Dutch cyclists said they listened to music during (almost) every trip.

More than 3% of the cyclists report making or receiving a phone call during (almost) every trip.

Approximately 9% [of] bicycle crashes with injury are preceded by the cyclist using devices.

These data are wholly consistent with the hypothesis that phones cause significant added risk and music players do not. Without being able to separate these two groups, however, it actually seems quite possible that music listeners may be under-represented in the crash figures: are they actually less likely to be involved in a collision?

Is there even a worthwhile hypothesis that music listeners are safer? Just as there is a hypothesis that non-helmeted cyclists may be safer because they are less inclined to risk compensation, is there also one that aurally-restricted cyclists are safer because they do not rely on sound signals (which are unreliable) and instead increase their reliance on visual checks (which are highly reliable)? This takes question 5 above and changes it: Do the strategies adopted by headphone users actually improve safety?

Some soundbites

When we break the problem down into testable questions, we find some interesting things, both in terms of the logic and the statistics. Two conclusions stand out:

  • Given sound measurement data and the sameness of the auditory content, it seems impossible to argue a case for banning headphones without that argument being wholly inconsistent with the use of roads by deaf people and/or people in enclosed vehicles.
  • The statistics relating to collisions are murky. There seems to be no compelling evidence that safety is compromised, despite there being clear evidence for loss of hearing. Moreover, the data may even show an improvement in safety and one might hypothesise that this is because loss of hearing increases reliance on the more reliable sense of sight.

However, whatever the data show, like any discussion about restricting cyclists’ behaviour on the basis of things that seem obvious to others, I’m sure this will rumble on.

And, like all those discussions, all this noise achieves is distraction from the real way to solve the problem.

Hit play, hit repeat.

 

21 thoughts on “The Sounds of Science

  1. Bez 5 November 2014 / 08:48

    Footnote: personal experience

    Having ridden for over 20 years and having never done so with headphones (I mostly ride rural roads and quite like getting away from technology, and—yes—I did think riding with reduced hearing would be at least disconcerting if not more risky), I thought I’d give them a go before tacking this subject.

    Some assorted notes from my experience:

    • I used two types of headphones: some behind-head buds (as shown in the picture above) and some in-ear buds. The former had only a marginal effect on my ability to hear my surroundings; the latter a significant one (they have rubber parts which effectively seal the ear; to be honest I don’t like this “underwater” effect even if I’m just sitting at a desk).
      Content makes a difference. I don’t perceive listening to music to be a significant cognitive distraction; however, I recall once trying to learn Spanish from a CD in the car, and I persisted only a couple of minutes before deciding that it was too distracting to be safe.
    • Noise is an unreliable mechanism for evaluating position or speed. Distinguishing the source is particularly difficult when there are many sources. At speeds above 10-15mph, noise also arises from airflow around the ears, glasses, helmet, clothing and so on; there have been occasions in the past when I have looked behind expecting to see a car that I’d heard, only to realise it was just the noise of turbulent air passing over my shoulders.
    • Manoeuvres demand visual checks in order to be confident. I do wonder whether sound can offer a false sense of security and whether one is more likely to use sight if sound is diminished.
    • I felt slightly self-conscious using headphones, knowing that they were visible and that there is a common opinion that using them is irresponsible. But that’s not really a safety issue.
    • Overall, I felt at no significant additional risk using either type of headphones. I certainly felt uncomfortable (mentally, not physically) with the in-ear buds, but it’s very hard to say whether this might affect my safety. I found the open-ear buds (shown above) to be absolutely fine, other than that they generated a lot of wind noise above jogging/running speeds. I’m inclined to test them under my winter cap, which has fabric covering the ears and would eliminate the noise from the airflow.
    • Crucially, I haven’t encountered—and nor can I immediately think of—a scenario where my cycling behaviour would be significantly influenced by a loss of hearing. If I have to make a manoeuvre myself, I check visually; whether that’s moving across the lane or tackling a junction. In the potential collision of a driver hitting me from behind, I would be able to do nothing even if I heard the car, because a car which is about to pass safely sounds exactly like a car which is about to drive into the back of you. To me, sight is what is required; hearing is at best only marginally useful and at worst misleading.

    Will I become “a user”? Not generally, no. I don’t feel the need, and frankly the wires are a faff. But I do sometimes ride through the night on rural roads, where there is little to see or to occupy the mind, and I will see if listening to music helps me through the long hours of darkness.

  2. Andrew Taylor 5 November 2014 / 09:15

    Just to throw a spanner in the works, has anyone done a survey on how using a mobile phone via the earpiece and “remote control” affects driving as this is becoming the norm for the tightwads to cheap to buy a proper Bluetooth device. The driver still has to (illegally) handle the phone whilst driving to dial out then fiddles with the earpiece wire to find the “remote” speak/listen/answer/disconnect button all whilst controlling a ton of moving metal. Yet again a straw man arguement is thrown up to vilify the cyclist and devolve responsiblity away from the real villains, the irresponsible & bad motorists.
    And before people ask, 1) yes I drive, yes I have Bluetooth, no I don’t use it regularly & if I do I dial whilst stationary. 2) No I don’t use headphones whilst cycling but that’s for aesthetic reasons, I like the sound of the wind when I ride

    • donk 5 November 2014 / 15:12

      “the tightwads to cheap to buy a proper Bluetooth device. The driver still has to (illegally) handle the phone whilst driving to dial out” TBH I’m not sure if looking down to dial your phone is very different from looking across to dial using whatever dashboard device dials your phone for you – both are detrimental to driving, leaving aside the actual having a conversation* aspect. Or are all fancy bluetooth cars voice activated? and if so do they take an IT specialist to programme the numbers in? ie hardly anyone will utilise the voice activation. Modern cars do _seem_ to have a lot of distractions available whilst also isolating you from what’s outside the car as much as possible.

      besides the default tightwad “handsfree” kit around here is holding your phone up to your face :rollyeyes:

      *conversations with car passengers are a bit different imo.

      • Simon Lownsborough 6 March 2015 / 04:13

        Hi – first time poster. I am a long-time cyclist. Recently I installed hands-free bluetooth in my car. I think it is a perfectly safe device because: it automatically collects all contacts from my smart phone (so no programming-in of data), and it is voice activated. At most I push one button to begin the call, then say the name of the person I wish to call, then say ‘end call’ to, well, end the call.

        It’s arguably less distracting than adjusting your airconditioning or music system.

        As for using ear buds – yes, why not. I have done a LOT of riding both with earbuds and without. The most important point here is ALL OF YOUR RIDING IS VISUAL. If you make a riding decision based on sound you are basically riding blind. And, either with buds or without, I am more aware of traffic conditions on the bike than in my car listening to whatever 80’s neon band I call music.

        The few times I have had close calls with cars passing there was absolutely no warning or time to act. Most dangers to bicycles come from in front and to the side. The few that come from behind, well, you are at their mercy.

        Calling for a ban also ignores those with hearing disabilities, motorcyclists with closed-style helmets, cyclists (and pedestrians, moped riders etc for that matter) wearing ear muffs so their ears don’t freeze off – I’m sure the list goes on.

        Arguing for a ban on on- or in-ear music is just passing the burden of safety back onto vulnerable road users, rather than educating all road users to share and not run each other over. More than that, it is ignorant.

  3. Andrew Taylor 5 November 2014 / 09:32

    Just seen todays click bait cycling article under the heading “Would these five changes actually help cyclists?” here http://www.bbc.co.uk/news/magazine-29894590 which includes this topic as one of the safety issues. Being the BBC it only actually lists 4 changes and failts to mention implicit liability for motorists, yet another balance article from the BBC……not.

  4. Mike Dowler 5 November 2014 / 11:03

    Unfortunately, this post starts by asking the right questions, but then leaps to the wrong conclusions in the same manner complained about.

    The question that needs to be asked about deaf cyclists and car drivers is exactly the same as for cyclists with headphones: is there an unacceptable inability to react to the road conditions? It is *perfectly* possible that deaf cyclists, being used to the lack of auditory input, are better able to make use of visual signals and ride appropriately. There is no logical fallacy in making a distinction, and each case must be decided independently based on appropriate evidence.

    • Bez 5 November 2014 / 11:10

      A fair point, though one could infer something along these lines from the Netherlands’ collision data: 15% of cyclists use headphones “on (almost) every journey” and thus are conditioned to whatever loss of hearing ability accompanies their own particular equipment. And the collision data suggests that they may be under-represented.

      The point here is that nothing excludes the possibility that non-deaf cyclists can condition themselves to a lack of auditory input. Indeed, if my own experience is representative, I certainly found myself becoming more comfortable with it, despite it initially feeling “different”. I was certainly looking more, but that was in order to test whether I was missing anything by having reduced auditory input. I’d have to persevere a little to get a better feel for whether I’d look more in general (which, if so, could imply that I’m relying too little on shoulder checks at the moment).

  5. Andrewwd (@Andrewwd) 5 November 2014 / 11:36

    As with many cycling topics, I think this is a question in which the definition of ‘safe’ is being framed wrongly.

    As usual, the tendency is to use safe as analogous to protected, which it is not.

    A morally acceptable definition of safe in this question is; does the use of headphones make me more dangerous to others? In the UK, where there are no simultaneous green junctions, the answer is no, wearing headphones does not make me more dangerous. Since I cannot travel backwards on a bicycle (I’m not Danny MacAskill), my ability to mitigate for hazards is not affected; I can operate my bicycle in exactly the same way as without headphones. This seems facetious but is a very important point. When learning to drive, I was taught it can be useful when reversing to wind a window down and listen. Bikes however, unlike cars, cannot make reversing maneuvers and do not have restricted visibility. Caveat: in The Netherlands where there are simultaneous green lights for cyclists the moral imperative to listen and verbally communicate when able may discourage the use of headphones.

    On the other hand, does wearing headphones make me less able evade the dangerous actions of those around me? Possibly yes.

    Like the helmets or hi-vis debate, the question highlights that we live in an environment where sadly it is incumbent upon the most vulnerable to protect themselves from the most dangerous.

  6. stevencastle 5 November 2014 / 11:41

    Lots of useful information here, I enjoyed reading it.

    I used to cycle with headphones in but mostly right ear out, so as to hear better on the ‘traffic side’. Sometimes whilst heading through parks and cycle paths I’d put both in and was wearing both ears in when a dog ran out of a bush in front of me and I headed over the bars and later to A&E with a wrist fracture!

    I did ride with music after that but then stopped. I’m a sound engineer by day, so maybe am more used to taking audio cues. I listen for the sound of engines behind me as a cue whether to be cautious, brace myself or whether it is acceptable to sprint onwards. I rarely use audio cues at T junctions though, always preferring to stop and look.

    I would think that those Dutch people who regularly listen to music are doing so on lovely Dutch infrastructure, where it would be a pleasure to ride… Until we get the same (….!…) I’ll stick to keeping an ear out!

  7. donk 5 November 2014 / 15:22

    Nice write up. I’m an occasional “user”, offroad and quite road rides I like some tunes on, in traffic along with helmet and (sometimes) high viz use, i’ve been coered into towing the publicly perceived “common sense” line.

    Mostly this argument seems to be just more outgroup bashing/victim blaming.

    • donk 5 November 2014 / 15:23

      typo – quiet road rides not “quite”

  8. Tim 5 November 2014 / 16:11

    Interesting. Your point about “one would also have to argue that car stereos would have to be banned” often seems to be ignored precisely because cyclists are at higher risk – more fragile – so it’s somehow up to them to take responsibility for that risk. “Of course drivers can listen to music; they aren’t the ones who are going to get run over.”.

    • Tim 5 November 2014 / 16:11

      …the new family of meerkats arrives at the zoo only to discover no meerkat enclosure has been built so they have to move in with the lions, much to their concern.

      Of course the lions are very dangerous and accordingly they have strict rules regarding their supervision etc. And since the meerkats will be sharing (albeit against their will) they will have to obey the same strict rules. The meerkats feel this adds insult to potential injury – the rules are because of the lions, not them!

      And to make matters worse, the lions have the benefit of being big enough to defend themselves, but the meerkats aren’t (against the lions) so in practice the meerkats end up having even harsher standards applied to them.

  9. rdrf 5 November 2014 / 21:27

    I’ve seen people in cars talking to each other. (I have, really.) It must have the potential to disrupt the attention of the driver, even if (s)he isn’t the one having a conversation.

    After all, you wouldn’t to be chatting away in a driving test, would you?

    So, never mind mobiles, social media, radios, bluetooths etc. – how about banning talking in cars? Seems at least as sensible as the drivel about cyclists’ headphones.

  10. Haze 7 November 2014 / 21:38

    Is it fair to compare music in cars with cyclists’ headphones? Couldn’t it be argued that cyclists, not having the benefit of mirrors, rely on sound more than drivers?

    That said in my experience it tends to be the sound of motors that drowns out the sound of headphone music rather than vice versa so I’m not sure it’s that much of an issue.

    • michael 25 July 2015 / 18:23

      But drivers need mirrors because the all-round visibility from within a car is very poor, compared to someone on a bike (without even mentioning the issue of trucks).

  11. samsaundersbristol 4 March 2015 / 10:48

    I’m just reading Joe Banks’s “Rorsach Audio: Art and Illusion For Sound” and it reminds me how unreliable common sense and personal anecdote are in trying to link aural perception with understanding or action. We really don’t know much and what we do know yields no clear guidance one way or the other. The kinds of naive experiments described above are often based on oversimplified assumptions about how hearing works (or doesn’t work) in the complex and highly variable phenomenology of real life cycling.

    We would do better to concentrate on known hazards and remove them. Do the big things and worry less about the subtleties. Number one would be to improve the poor surfaces that contribute so significantly to the numbers of cyclists who end up in A&E. Ice, mud, water, pot holes, kerbs… fix all that stuff. Alongside that the well argued “Space4Cycling” agenda gives us more than enough stuff to do. Conversation about audio devices, while interesting, is a red herring. We already know the causes of most injuries to people who cycle and we should do a lot more to reduce them.

  12. greg 7 March 2015 / 01:52

    no-one has mentioned a benefit of using earphones- I have been startled by yobbo drivers that like to yell,rev their engine,sound their horn,etc.,just as they pass my bicycle- since using earphones,sudden loud noises are effectively subdued.

  13. michael 25 July 2015 / 18:21

    I don’t know about these mythical ‘auditory stop signals’ but personally I feel that listening to headphones _does_ adversely affect my concentration. It occurs even if I’m attempting some fiddly task at home. When the parts involved in some annoying repair job prove recalcitrant I have to turn the music off or take the headphones off (and swear a lot).

    Of course,this does raise the question of why its considered OK for drivers to have the car stereo on. Indeed, if its not OK for me to listen to my own music, why is it OK for me on my bike to listen to the deafening boom-boom-boom from the sound-system of the car next to me in the traffic?

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