Category Archives: Road Traffic Noise

I’ve only just started freelancing on my own. Unlike the initial  romanticised impression of acoustics being the perfect mix of music, maths and physics, I really spend most of my day listening to noise :). So I thought I should get my hearing tested for two reasons:

  1. To have a point of reference for a ‘before’ and ‘after’ scenario of my hearing sensitivity.
  2. To understand what frequencies I am sensitive to, and any hearing losses I may have for other frequencies – so that I can accurately tune listening spaces.

I went to this institute near my place and found out two things that didn’t suit my needs.

  1. I could hear road noise very clearly inside their listening room! This is past 3 doors, no less – the entrance door, the door to the audiologist’s room, and the door of the listening booth.
  2. They test only 5 frequencies from 250 Hz to 8 kHz, because this is primarily for old people to hear speech.  For my purpose of tuning spaces for music, I need to be tested for a much wider range – 50 Hz to 18 kHz.

Anyway, I went ahead and turns out my hearing is normal, but I suspect it won’t stay so for long. I am a tad sensitive to vocal high pitches – the Lata Mangeshkar types – playing those at normal volumes can grate on my ears. But I did have difficulty in listening to low pitches – the 250 Hz thing. This would’ve been critical information for me to have found out – except that I will have to take it with a pinch of salt, pending more accurate tests. There was plenty of low noise infiltration through the doors, and I could hear them despite the on-ear headphone.

Anyway, the point is, that critical spaces such as these must not have any type of noise coming in. They had even used thermocol for acoustical isolation. Thermocol, styrofoam are easily and cheaply available, but they are not acoustical materials at all – they can at best be used for impact isolation.  There was also some masking effect happening due to road noise intrusion. I could clearly tell the sound of an auto, a bike, a bus, and some local vegetable vendor hawking at a loud voice.  This is also because the glazing they had used was rather thin. It is critical for listening booths to have glazing because they are to be closed, and the only way for the audiologist to know that you are able to hear a certain test frequency, is when you raise your hand. They have to be able to see you. Glazing itself is not a problem, but the right thickness must be used. Also for such applications, either in-ear earphones, or supra-aural earphones must be used. On-ear headphones are not very effective for blocking out sound.

These and many other defects can be solved right at the design stage.  Eventually, the kind of hearing aids that are prescribed are primarily influenced by the extent of the patient’s hearing loss, and the budget.  The first factor – the extent of the patient’s hearing loss can be accurately gauged if external interference is zero. In this case, it is critical to avoid masking effects.

The right technical advice will take into not just that, but also the hum of your HVAC, the type of earphones you must use, the influence of nearby buildings and their DG sets, etc.  It should also prescribe materials from a rough-use point of view (for instance, the rubber linings of the door had peeled off – leading to a compromise in sound isolation). For a place primarily meant for accurate testing of hearing loss, the noise constraints posed by the location can be easily overcome with correct acoustical diagnosis, testing and recommendation.

There is one rather disturbing aspect of road noise on the rise. It is that the soundscape in India has drastically changed in the last ten years alone, never mind my growing years. Post liberalization, and 10 years post that, with increasing affluence,  there are plenty of SUVs on the road. While engines have grown quieter (and dangerously so – I can’t hear cars creep up behind me on the road!),  horns have grown increasingly louder. It is not unusual to hear an SUV honk at 110 dB to a guy standing just 2 feet away.  Yes, on some roads in India,  cattle, people, cyclists, SUVs still go shoulder to shoulder.  Just to give you an idea of how loud 110dB can be, imagine standing next to a jet engine, or in a loud discotheque. Of course, imagine that you stood only for 2 seconds, because that’s how long the horn lasts. But I must confess, at my seemingly young age, my ears ring for 5 seconds after I experience such inconsiderate honking.  To make matters worse, there are articles like this :  http://jalopnik.com/5896859/audi-is-designing-extra-loud-horns-for-india

Now this rant is entirely based on that article I read. I am assuming it is true. I am hardly feeling rational and sane right now, but I’ll attempt to be. So I understand the need for a foreign automobile company to design mechanically sturdier horns for the Indian scenario, given that lane discipline is rare and horns are a necessity here. But why “louder” horns?. I think the engineers who came up with this thought are shortsighted, to say the least.  I really wish to go honking near their homes with this very horn they’ve designed. 

Someday in the not-so- distant future. I will move a petition, with the eventual hope of seeing it implemented as a legislation – to force automobile manufacturers to have two different volumes for horns built in. Just like high beam and low beam for lights. Shouldn’t be difficult for them to do this, and it would make our cities that much quieter. All this hullabaloo wouldn’t be necessary if temporary deafness was an immediate effect. The sad truth is, it only sets in later.

What does NIHD mean to you?

I’ve heard varied answers for this, with some people even guessing that it was a new kind of battery for cameras. I’m of course, talking about Noise Induced Hearing Deficiency. Given how commonplace it is now, it is surprising that nobody really knows about it. It is not surprising, it is actually alarming. The only explanation to this is that any form of deafness earlier was attributed to age, or accidents.  The truth is, NIHD is tragic. It is the most easily avoidable kind of occupational injury. Situations causing NIHD are much more rampant now.  This blog discusses NIHD in the Indian context, and how we owe it to ourselves to take the simple precautions that will help us keep our hearing mechanism healthy.

Here goes:

What is NIHD, and why should I give it any thought? 

Imagine not being able to hear half the consonants. “Steve, watch out for that pipe” sounds like ” ee, o ou o aa i “. You haven’t lost your hearing yet. But there’s no quality of life if there’s no quality of conversation. That’s what a person with NIHD will go through in their alarmingly near future.

Imagine sitting around with your best friends at your local cafe, sipping coffee, watching and hearing everyone talk and laugh, and not quite be able to make out the words. You hear sounds, but they don’t sound like the words you know.

 It is likely that you will spend this evening and all such evenings further on just sitting around, not really being a part of the conversations.  There are already enough teenagers in the US, who’ve battered their delicate hearing mechanism with abnormally loud music for hours on end, and who now cannot hear their friend whisper a remark into their ear while sitting in class.

Hearing loss affects the high frequency range of your hearing, and many consonants of our alphabet lie within that.  Here is a wonderful youtube video that explains more.

[youtube=http://www.youtube.com/watch?v=d_KS-MB0jTU]

The solution?

  • The previous post “Sound – the Fourth Dimension” lists steps you can take to make your hearing sharper.
  • The simplest solution is to use ear plugs whenever you are unavoidably facing loud noise for long amounts of time. 

The hearing mechanism is so delicate, that the wonder of it deserves another post  – coming up soon! I hope you will be left with a feeling of awe at the end of it. :).  Meanwhile, Steve, watch out for that little pipe in your ear.  Use ear plugs.

 This is part 2 of a multi-part article that lists out common noise sources and their effects on the quality of our lives.  Part 1 deals with community noise. 

Road Noise particularly deserves a separate blog post. This is the most common problem faced by independent houses, hospitals, auditoria,  independant small business offices, and even some large corporate offices in Bangalore.

Scene 1: Cities grow. When people bought plots and built houses, they were located away from the noisy, bustling city center and business districts, because land was always cheaper farther off. There WAS no noise then to take care of. Once the cities grew around there, suddenly small roads became main roads. Now windows rattle when trucks lumber along, and cars drown out conversations unless you shut out ventilation. Bangaloreans now have to roll up their car windows on noisy, arterial roads (such as J. C. Road) if they want to hear any conversation or radio. At the minimum, a person drives for upwards of an hour or two each day to commute. This city is facing unprecedented growth, and therefore there’s ample construction and road traffic noise.

Scene 2:  Vehicle Noise. Another example. I have the luxury of having Sir C. V. Raman’s property right next to my house. It’s a huge property, with much of the place covered with trees, and a very small construction on one end of it. My house is separated from the road by nearly 200 ft of this gap with tree covering. Yet, I feel the need to close the shutters when I’m in the hall, to hear conversation. I shudder to think how I’d be up the wall with noise if there wasn’t this much of gap. The horns are loud enough to irritate when one is quietly working or reading.  While Bangalore is now seeing a lot of high rise buildings,  there’s a huge amount of residences that are not so huge, and these small clusters of apartments and independent houses are directly built next to a main road or two.

Scene 3: Structural Vibrations:  I knew someone whose house was located 50 ft from the national highway.  Now that might sound like wierd planning, but national highways do pass through cities, and there’s bound to be residences on some stretch of it inside the city.  The planners did their bit and built a 30ft wide park all along the road, and then a small 20ft wide service road in front of the houses.  Add to this, interstate trucks and lorries are not allowed inside city limits for most of the day – they were let in only during select entry hours.  Secure enough? This person was rattled awake every morning at 4 a.m, when trucks were allowed to pass and his window panes would rattle.  The low rumble would dance on his chest and make him hypertensive. He’d toss and turn, and blame it on the anxiety he felt.

Scene 4: Ultra Loud Horns from SUVs. This is a rather disturbing trend on the rise. It is not unusual to hear an SUV honk at 110 dB to a guy standing just 2 feet away.  That’s as loud as a jet engine, or a discotheque. That can blast in your ears even if you are a good  50 feet away, and  if you’re ears are fatigued, they can ring for 5 seconds after such a honk.  This situation didn’t exist till even 5 years back, when SUVs were not plentiful on the roads. If you live next to a noisy road, the damage these loud horns can cause in the long run are not limited to Auditory fatigue or a temporary shift in the threshold of hearing.  The point here is that this is now a huge factor that  Acoustical Consultants take into consideration while designing sound spaces, because at 11odB, this is rather obtrusive.  The fact is that such a level of loudness is unnecessary within city limits, where you can’t be zipping at the speed of light. You have to move at mob speed, and a softer horn , even at 85-90 dB will be alot easier on our ears. More on this in another article.

For now, these are are the common scenarios in today’s cityscape.

The next article deals with noise in office spaces here.