Are You Listening?

Posted by
Thu, 28/07/2016 - 14:53

Gareth Davies - July 2016

We live in a technological world. Everywhere we go we can summon the power of technology to help, inform or entertain us. Innovation is moving so fast that once unimagined technology is now deemed necessary within the space of a few decades; for instance, the Internet. Perhaps evidence of this continual progression is most pertinent in the quick birth and death of gadgets such as pagers, and mini-disc. Largely, reliance on technology has been intoxicating, rapid and invasive, treated with suspicion by the few who are happy in their ways but otherwise embraced as obvious advances for all sorts of applications...including acoustics.

Over the last few years I have been bombarded with various acoustic technologies (sound level meters, vibration meters, CadnaA etc.) that are all designed to make our lives easier. I am able to create lots of data for spreadsheet analysis without too much trouble.

However, it hasn't always been like this. On occasions, senior Institute members have described to me the technologies they used during their formative acoustic years. This has included stories of tracing reverberation measurements frequency by frequency, continuous level readings jotted down in note books from large cumbersome machinery, and numerous attended 24 hour surveys. It seemed to me to be a lot of work for a little bit of data! Furthermore, analysis was done by handwritten calculations without a computer spreadsheet in sight.

On the face of it this seems like a great deal for us younger members. We have avoided long nights and laborious analysis, our hardware and software packages do the hard yards for us. Yet I am struck that technology (not only in acoustics) also engenders disconnection from the real world. What this data tells us is nothing without the real context, do we need a number to say if something is too loud or not? Are we really listening to the world we are in and the work we do? Would we be better off doing the hard yards to get a better understanding of our conclusions?

With this in mind I took a sound level meter out with me and measured my typical working day, and separately made subjective notes as a comparison.

I live in London so I expect an urban environment. Indoor levels were generally below 60 dB LAeq and outdoors ranged from 70-85 dB LAeq. The tube generated LAmax levels in excess of 100 dB consisting of horrible screeches from the wheels on the line. Yet the loudest noise was reserved for England's last minute winner against Wales at Euro96 (106 dB) – I had popped my head in to a pub to check the score on the way to an attended survey.

It was interesting to note how distracting everyday noises were once I began to notate my day. Apart from night-time (23:00-07:00 hours as we have all agreed!) my aural environment was bombarded, and it would seem that the soundscape I was exposed to was not definable by the numbers alone. For example, the screech of the wheels of the tube is certainly less pleasurable than the cheering of an England goal, despite the latter being louder.

With this in mind it is important to listen, when on site, at work, anywhere, to provide clearer purpose to our analysis that isn't being led by the data. Hypothetically the experience of attended 24 hour surveys, long form analysis etc. may provide a greater understanding of our conclusions.

All that being said, I'm not about to throw the new out for the old – certainly if I can avoid taking measurements over 24 hours. However, it is good practice to stick to the basics, and to become an accomplished acoustician you must regularly ask yourself, "Am I listening?".