Music & Harmonics
Research: Much work has been carried out in the area of sound analysis with regards to crop circles, initially inspired by various sounds and 'tones' heard in some of the early formations. One such famous case was the trilling noise recorded at the Operation White Crow event which took place in 1989.

Early work and theories
The trilling sound was one I was lucky to perform analysis on myself, after Colin Andrews kindly loaned me a copy of the original recording. It consisted of a number of short bursts of oscillating tones, recorded on audio tape. Sceptics and hoaxers, including Doug and Dave, were quick to come forward and claim that the noise was in fact that of the Grasshopper warbler, a small bird. However, what they neglected to take into account was that the grasshopper warbler is actually quite rare and it's haunt is downs, commons and marshes - hardly crop fields.
However, the most conclusive evidence was discovered some time later whilst I was hunting through a BBC sound effects archive. I discovered a CD recording of the actual grasshopper warbler, along with all the other native warblers of the UK. I duly sampled this sounds into the computer and compared the frequency waveform and fourier analysis of the warblers with the recording Colin had made at Operation White Crow. The two were clearly not the same, as shown in the diagram below.

As you can see, the sound recorded at White Crow is mainly around the 4KHz frequency, whereas the real grasshopper warbler oscillates at around 6KHz - nearly 2KHz higher in frequency. I have subsequently analysed a further two samples of the real grasshopper warbler and both gave the same readings as shown above. I think you'll agree that this confirms that Colin Andrew's White Crow noise was not a grasshopper warbler.
If you would like to listen to the two sounds yourself, I've provided short samples below, for you to download and playback yourself.
Download a 56K .wav sample of the White Crow recording.
Download a 70K .wav sample of the real grasshopper warbler.
If anyone else has recorded strange sounds or noises in the vicinity of crop circles or UFO sightings, I would be very interested to carry out further analysis on audio recordings.

Diatonic Ratios and Harmonic Geometries
One of the first researchers to point out links with musical scales was Gerald Hawkings, a retired professor of astronomy at Boston University. Having worked at the Harvard-Smithsonian Observatory in the 1960's, he had already done much research on the astronomical importance of Stonehenge. After earning a subsidiary degree in Pure Mathematics from London University he analysed aerial photographs and ground surveys of crop circles and was surprised to spot a clue to their possible origins - lying in the ratios of musical notes.
If we examine the exact frequency of the white notes on a piano we will find that, with perfect tuning, the note middle C has a pitch of 264Hz (vibrations per second). If we play the C note in the octave above (C') we will find that the frequency is 528Hz. This is exactly double, giving a ratio of 2:1.
If we now examine every note in the major scale we will find an elegant, yet exact, diatonic ratio - shown in the diagram below.

These ratios are fundamental to music because as we rise each octave above middle C exactly the same ratios are used but doubled. For example, E' (Each ' is used to represent the rise of one octave) has a ratio of 10/4 and A'' gives 20/3. These ratios also give the intervals in all the notes in the other major keys too.
So, how does this relate to crop circles?
When we started analysing the ground surveys of crop formations we started to find that the same diatonic ratios started showing up in the relationship between various elements of the formation - either the ratio of a circle to it's ring, or perhaps a large circle surrounded by smaller satellite circles. Gerald analysed the entire sample of circles accurately measured by Colin Andrews and Pat Delgado between 1981 and 1988. Out of a total of 18 formations, 11 gave diatonic ratios.
In 1988 a formation was discovered at Corhampton in Hampshire which not only contained diatonic ratios, but also precise Euclidian mathematics. This ultimately gave rise to five crop circle theorems. If you would like more information on Hawkin's crop circle theorems I would recommend visiting Freddy Silva's Crop Circular web site, which explains them well.
Circular Harmonics
When I first heard of this Hawkin's, I became intrigued, strongly believing that he may indeed be onto something. He had already contacted me to comment on my three dimensional geometrical analysis, and I was now becoming intrigued by the 'musical link' being interested in this aspect of research myself.
One day, whilst working in my capacity as a computer programmer, I discovered a program for the Acorn Archimedes range of computers which could take a scanned photograph and 'play' it as a sequence of tones, or harmonic scales. I decided to experiment with some crop circle photographs to see what tones were produced. I decided to initially try with a scanned aerial photograph of the famous Mandlebrot formation which appeared in Cambridge in 1991. I loaded it into the computer programme and started it running. What came out of my speakers quite surprised me. It wasn't exactly music, but it was certainly not objectionable. In fact it sounded almost like some of the 'new age' music tapes you can buy. After a few moments, the tones become almost hypnotic and I was sure they may be beneficial to meditation. Perhaps it could be a way to communicate with the circle makers....
I decided to develop my own computer software based upon this initial idea, and to take it a step further and be able to not only geometrically analyse and 'measure' the formations but also 'play' them as music using a set of basic musical rules.
Over the years this software has developed and can now perform quite complex analysis and synthesis of musical tones and harmonics based either on the actual 'pixels' in the image or on the actual physical ratios of the formation itself. Being initially surprised (and impressed) with the results, I decided to 'record' some more formations and went on to examine a computer drawing of the actual Mandlebrot set, along with scanned photographs of the first 1994 Galaxy formation which appeared along the Avenbury Avenue and the 1994 Oliver's Castle formation which appeared in the punchbowl near Devizes.
I left the sounds playing for 60 minutes and subsequently recorded them onto an audio tape, of which copies are available for for research purposes. Due to popular demand, I've recently produced a CD of these sounds too. Please feel free to email me if you are interested in obtaining a copy for your own research, meditation or healing purposes.
A short sample of the CD is available to download as a WAV file, but please note that the sample here has been converted to mono, 11KHz in order to make it small enough to download. The original is of much higher (stereo, 44KHz) quality.
Download a .WAV sample of my recording lasting 26 seconds. (819K)
This work is currently very much underway and I hope to report more findings over the next few months.