Back before the internet, twitter and megaphones it was a great deal more difficult to get your voice heard. However, those clever Greeks and Romans had a way of using the science of acoustics to get their message out.
They constructed great amphitheatres which seated thousands. An example of which is the image below I took when exploring an ancient Roman site in rural Turkey.
Click for High Def version
Scientists have continued to do research the way the acoustics worked to propel the voice of those ‘on stage’. A study by K. Chourmouziadou & J. Kang, published in the Journal of Applied Acoustics showed that amphitheatres evolved and changes in materials as well as design resulted in acoustic improvements. They simulated 6 different theatre types: Minoan, Pre-Aeschylean, Early Classic, Classic, Hellenistic and Roman. Each of these had different characteristics (figure 1)
Figure 1: A breakdown of the different theatre types
Figure 2: Over time the amount of reverberation in an occupied theatre is seen to increase
The researchers then used acoustic simulation software to examine the theaters. They monitored the absorption and scattering conditions in each incarnation of the theatre. Their results indicated that there was increased reverberation time as the theatres evolved (figure 2) and the speech transmission increased in occupied theatres. They concluded that overall the evolution of the theatres brought about an improved listening experience.
CHOURMOUZIADOU, K., & KANG, J. (2008). Acoustic evolution of ancient Greek and Roman theatres Applied Acoustics, 69 (6), 514-529 DOI: 10.1016/j.apacoust.2006.12.009
First of all a big thank you to everyone who took part in this little experiment. Secondly, sorry this post is a little later than I originally said it would be.
I was inspired to try this after listening to the sound and reading about what its effects should be. I was surprised to find that it’s effects worked on me, but I was curious as to whether that was the placebo effect because I knew what was supposed to happen. So that was the motivation for the experiment. The results were very interesting, 21 votes were recorded and were as follows:
What Effect Did the Sound Have On You?
None – 6 – 29%
Made me feel energised – 8 – 38%
Made me feel strange – 6 – 29%
Made me feel sleepy – 1 – 5%
But, what was the sound? Well, this experiment looked at the effects of binaural beats. An EEG detects different frequency waves in the brain during different mental states. The theory of binaural beats is that by listening to a particular frequency the brain enters the state of mind corresponding tp the EEG , as below:
> 40 Hz
Higher mental activity, including perception, problem solving, fear, and consciousness
Active, busy or anxious thinking and active concentration, arousal, cognition, and or paranoia
Relaxation (while awake), pre-sleep and pre-wake drowsiness, REM sleep, Dreams
deep meditation/relaxation, NREM sleep
< 4 Hz
Deep dreamless sleep, loss of body awareness
The sound in the experiment was a Theta wave. Therefore, should have created feelings of being tired and sleepiness. The poll on my original post found very different results with feeling “energised” the most popular feeling due to the sound and feeling “sleepy” the least popular.
This is obviously not a 100% accurate study. I have no idea how long the people who voted listened for, what they listened with (supposedly headphones makes the effect much more pronounced) or what environment they were in. As a result, with a small sample size and these big unknowns the inverse of the expected results is, ironically, not unexpected!
There have been lots of suggested (and unproven) uses and effects of binaural beats including improving memory, sporting performance, stopping smoking, dieting help and tackling erectile dysfunction. Some have even referred to it as an “auditory alternative medicine”! Even more bizarrely some people are claiming that this technology can be used to create drug like effects known as “i-dosing”. The effects of these sounds are still being studied and their actual effects is hotly debated with some maintaining that it is all placebo.
To me, without being able to find sufficient research on the effects of the sounds, I find it hard to draw a conclusion about the effects. I am willing to accept that binaural sounds may have a real effect on alertness. However, the more outlandish claims are really just ridiculous, and should be ignored.
To see an alarmist US news report on “i-doping” watch this video (sorry about the poor syncing of the audio):
[Update: to check out the results and explanations post click here]
So far in this blog I have pretty exclusively commented and reported on science. Well, today is a bit different. With your help we shall engage in a little experiment! [Update: to see the results and explaination post click here]
Embedded below is a sound that has some science theory behind it. To at least try and prevent any mean ol’ placebo results I am not going to say what the science is. The longer you listen to the sound the better, but I do understand that it isn’t particularly aurally pleasant! It also supposedly works best with headphones. [update: for some people it seems the embedded player doesn’t work if this happens to you the sound is also here]
Beneath the track is a poll to fill in after you have listened to the sound. Tomorrow (March 4th) I will reveal the results along with the theory, and we shall see if the science is right!
Also if people were to share this that would be great, the more data the merrier :D!