Shopkeepers: keep the noise to yourselves!
The Sunday Nation
Nairobi,
13 November 2011
Two years ago, the National Environment Management Authority published a
Legal Notice whose aim was to put limits on the amounts of noise that
are allowed in
The greatest culprits are shopkeepers who play loud music in their stores in an attempt to attract customers. However, the shops are next to one another and therefore, what might be enjoyable when inside one becomes discordant noise when it mixes with that from the neighbours.
So the question arises: what sound level should shopkeepers maintain in order to avoid creating noise on the streets? Let’s first do a bit of revision: sound levels are measured in decibels (dB), and a very good human ear can hear 0dB. Below that is completely silent, but that doesn’t mean there is no sound! A whisper is about 15dB, normal speech is 60dB and shouting approaches 100dB. Anything above 120dB can cause permanent deafness.
Now obviously, the farther away you are from a speaker, the lower the level of what you hear. Every time you double your distance from the source, the level drops by about 6dB. The reverse is obviously true – it gets louder by 6dB if you cut the gap by half.
Suppose the loudspeaker is placed inside the shop, 5m from the front door and we desire to maintain a barely audible 20dB on the street [remember, a whisper is 15dB]. What would be the sound level inside the shop?
Well, at half the distance, you will be almost at the centre of the shop and the sound level there would be 6dB higher, that is, 26dB. Now that is very low, especially if it is compared to the 60dB of normal speech.
What if the shopkeeper maintained the music at a level just above that of speech, say 65dB. What would be the sound level outside? Simply 65 – 6 = 59dB. That might look loud but let’s not forget that the shop is located on a street that has cars passing by.
The noise from the cars averages about 65dB to 70dB. Clearly then, pedestrians on that street will not hear the music. This is probably the reason why the shopkeepers pump up the volume to the annoying levels – they are aiming to be louder than the cars!
The result is, of course, a chain reaction: the first shop to open in the morning plays its music at slightly above street noise level; the second shop goes a notch above the new combined level (street plus first music); the third one…well, you know the drill!
So what do we do about all the noise? I think the time has come for the local councils to move-in and shut down shops that whose music can be heard from outside. Remember how they dealt with shouting matatu manambas? I don’t know about your route, but in mine the terminus is quit quiet…well until you enter the matatu and they switch on the music…
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