Surrounded by Sound

It's never quiet!  Sound abounds.  Unwanted sound is called noise, but this is where subjectivity comes in because one person's noise is another person's favourite sound.  Ask any parent who is frustrated with their teenage offspring's latest audio download!  In physics, sound is a vibration that propagates through a medium such as air or water and that's what this post is all about.

Have you ever experienced true silence?  It's a very rare occurrence although if you have ever been in an anechoic chamber, which I have, then apart from perhaps hearing your own bodily sounds, you will have been pretty close to experiencing absolute quiet.  That's because the anechoic chamber is echo-free and insulated from external sound.  But that's a rare environment.  As I write this post, I am sitting in a room with a temperature of 30 deg C + and so I can hear the sound of a fan blowing air across my desk.  It just so happens that I can also hear the Imam doing a call to prayers from a local mosque and there are various human-induced sounds around the house - clocks ticking, refrigerator pump, etc.

If I venture outside, then I can still hear sounds that are human-induced, like cars occasionally passing by on a nearby road but, at this time of the year and in daylight hours, there is the continuous sound of cicadas.  Ever heard of them?  No?  Well I hadn't until I lived in Turkey.  It is quite a remarkable insect.

There are at least 2,500 species of cicada and I have no idea what those are that live in my garden!  I live in a property surrounded by trees, which provide homes for the cicadas.  Most of their lives they live underground at depths ranging from 30 centimetres to 2.5 metres.  During that time, which can be up to 17 years, they feed on sap from the tree roots.  Eventually they emerge and males go to the trees where they 'sing'.  The cicadas have a noise maker (or should it be a sound maker?!) called a tymbal below each side of the abdominal region.  As they contract and relax they produce clicks.  The very loud continuous clicking sound is what is going on in my garden right now.  Is it a pleasant sound or just a noise?  Well that depends upon how I feel!  Apparently each species produces its own distinctive mating songs, which ensure they only attract the appropriate mates.

I mention the cicadas because they are unusual and not emitting sounds all year.  But there are loads of other sounds.  Inside and around the property there are geckos.

They are everywhere!  They also make sounds - clicking and chirping.  Add to that our two dogs and a cat, there is never a quiet moment!  What really interests me about the animal sounds is the fact that it is a form of communication that most of us really don't understand.  Zoologists have plenty of theories, many of which I am sure are close to being proven facts, but whereas when we walk into a crowded room the chitter chatter is decipherable, the noises (sorry, sounds!) from my cicadas and geckos don't convey any information to me.

But I'm never alone!!