Conspiracies and Inspiration:

This blog outlines the development of a project undertaken by four music technology students of the Queensland Conservatorium of Music. This project required us to create a ‘sound composition’ in response to the given theme. In this case, the theme was ‘conspiracies’.

Immediately we became intrigued by the countless YouTube videos that claim to show ‘free energy’ devices in action. This led us to the conspiracy of Free Energy Suppression, where it is claimed that novel energy generation methods have been masked by government bodies and power company executives. Energy is an immense industry that forms the backbone of the modern global economy. It is easy to see a motive for oil giants to ‘cover up’ an alternate energy source that might obstruct their all-important profits. With oil companies already owning substantial shares in clean power technology (Kramer, 2012), at least parts of this conspiracy may hold truth.

We were interested in creating our own version of a ‘free energy device’, or at least referencing the concept of free energy creation through the use of sound in this project.


Kramer, N. (2012). “Solar Manufacturers Owned by Oil Companies”. Retrived 28th October, 2012, from URL   <a href=”

Our inspirations:

Turning Sound Into Electricity

We soon stumbled upon the concept of turning sound itself into observable energy. Capturing sound and turning it into power in a similar way to a solar panel converting light into electricity would be a remarkable achievement.

At first, everybody we spoke to about the idea responded with a resounding ‘No, it can’t be done!’

We knew that a microphone produces electrical current indicative of the acoustic pressure applied to its diaphragm. Would it be possible to extend this concept so that we could use sound to power a visual cue such as an LED?

As music technologists, we were aware of two situations where a microphone could produce abnormally large quantities of power:

1)      A Yamaha NS-10 speaker is often used as a microphone on a kick drum. A ‘pad’ or attenuator is often required to reduce the signal before it enters a pre-amp.

2)      Piezoelectric contact microphones are often attached to acoustic guitars. These also can have high output levels.

We spoke to an electrician at a local audio manufacturer as well as some studio technicians about these ideas, but they all agreed that these concepts would not produce enough energy to power an LED.

Sub-woofer Powered LED.

We were finally able to convince a salesperson at a local electronics store that our idea was worth pursuing. We bought components for a circuit that would enable us to connect an LED to a sub-woofer (an extension of the NS-10 concept).

Prototype 1:

This circuit consisted of a rectifier, capacitor, and an LED.

Prototype 2:

This circuit added a voltage doubler circuit to prototype 1.

By ‘punching’ the sub-woofer cone, we were able to move the coil enough to power the LED. Unfortunately, it was impossible to apply an equivalent amount of force to the speaker cone using only sound pressure. While the sub-woofer cone is reasonably efficient at converting energy into sound, it is very inefficient at converting sound into energy.

We had a concept that had potential, but it needed to be far more efficient before it could turn on an LED using only sound power.

Piezoelectric Power

Our research led us to this video, which shows piezoelectric microphones being used to harness ultrasonic sound and power LEDs.

The report to accompany this project is available here:

While this report focuses on application for this technology, it indirectly explains that the secret to capturing enough energy to power an LED through sound is resonance. The parametric speaker in this video uses a constant carrier tone of 40kHtz (the human ear can only hear to 20kHtz) to transmit sound in an extremely focused ‘beam’. The piezo microphones used have a resonant frequency of 40kHtz. Like the Tarcoma Narrows Bridge that wildly shook and collapsed at its resonant frequency, the diaphragms on these microphones vibrate aggressively at their resonant frequency, resulting in an electrical output far higher than usual.

Our First Sound Powered Prototype:

What if we could take the ultrasonic powered LED concept and apply it to audible sound?

As this project needed to be musically orientated, ultrasonic frequencies were of no use here. Accordingly, we decided to experiment with applying the concept of resonance to a microphone with an audible resonant frequency. We sourced 6 ‘electro-acoustic transducers’ that were originally designed as ‘buzzers’ akin to those used in smoke detectors. These had a quoted resonant frequency of 4200Htz (well within the human hearing range).

To our astonishment, we were able to illuminate LEDs using sound that we could hear!

Prototype No. 3

Prototype No. 4 (Voltage doublers included)

The Grand Plan

With the concept fully proven, we could now consider the scale of our final presentation as well the musical implementation of the idea.

Due to the relatively high sound levels required to illuminate the LEDs, we decided that the trigger speaker and microphones would need to be housed in a soundproof enclosure. This would ensure observer comfort and optimum brightness of the lights.

We were able to source 100 piezoelectric diaphragm elements inside our budget, so it became feasible to create a large scale version of our earlier prototype that would include over 30 LEDs.

To make our project interactive and engaging, we decided to incorporate an exercise bike that would be used to activate the sound, which was our energy source. This would allow for many musical avenues to be explored aside from the pure sine wave tones that were optimal for turning on the LEDs.

Below is a diagram to illustrate our project:

The Sound Powered LED Circuit:

The final circuit design featured 98 piezo diaphragms and 32 LED lights. While voltage doublers were used in some of the prototypes, this design was decided against for the large scale circuit.

Voltage doubler circuit advantages:

  • Better phase coherence at most angles.
  • Lights will usually be brighter.

Voltage doubler circuit disadvantages:

  • Halves the ratio of LEDs:microphones
  • Greater cost.
  • Huge amounts of soldering required for 100 microphones.
  • Phase is less of an issue if the relationship between microphones and the sound source remains fixed.

Below is the circuit used for the final installation. This is the same as one of the circuits used in the University of Tokyo’s ultrasonic project.

This was multiplied 16 times, giving us a total of 32 LED lights. Fitting 98 piezo diaphragms into a small and phase coherent space was an interesting challenge. These microphones needed to be tessellated and layered upon each other to fit within the splay of a speaker horn at close proximity.

The circuit was wired together and mounted so that the microphones were placed within the soundproof enclosure and the LED’s sat outside.

By running sine wave sweeps through the circuit, we were able to determine that the resonant frequency of the piezo diaphragms was 2850Htz. Interestingly, the LEDs also lit up at the 5th of the resonant frequency (4275Htz). Due to there being some phase cancelling between the microphones wired in series, some LEDs illuminated brighter on the fundamental, while others were brighter on the dominant. The solution to this was to trigger the LEDs using both frequencies, which minimised the phase cancellation effect.


It’s All about the Box!!!


After preliminary testing of the piezo microphones, it was concluded that the SPL needed at the correct frequency was over 95db. This presented the group with the challenge of finding a way to contain this level so it would be suitable and safe for a public installation. Our solution was to create a soundproof enclosure to house the speaker and microphone array.

To achieve the required volume attenuation, the design needed to incorporate a number of isolated insulation layers. As the transfer of sound between mediums is inefficient, two walls separated by an air gap, for instance, is an effective method of absorbing sound energy. Initial sketches of the box idea can be seen here;

We used prototype no. 4 to test the projection qualities of the speaker horn. It was determined that the enclosure would need to be 20cm wide by 27cm high. The volume and splay of the horn suggested that a distance of 30 cm between the horn and microphones would yield the  best brightness. The internal dimensions would be roughly 25cm x 30cm x 45cm (to give us a bit of room to play with).

The Cabinet

We were able to attain an old P.A. speaker cabinet with suitable dimensions for the enclosures structure. The speaker cabinet also contained a PA horn which was suitable to project the trigger frequency.


Construction involved:

  • Removal of both the speaker and the horn.
  • Removal of the entire front section that housed the gill and speakers.
  • Creating a new housing for the horn to face inwards in the cabinet and sealing of the area where the microphone array would sit. 

The enclosure contained an isolated ‘box’ within the larger cabinet. In between the outer and inner boxes, there was a layer of high density insulation foam. Foam was also placed behind the horn to minimise sound coming from the rear of the cabinet.

A double glazed Perspex window was installed on the front face of the box so that both the microphone array and horn were on display. Shag-pile carpet was also used as an absorbent on the front and back wall of the microphone array enclosure.

We achieved our goal to make the SPL pleasant and safe for the public during the installation.

The Horn

The P.A. was required to produce a SPL of 90-100 dB. The horn that was attained in the Phonic speaker cabinet unfortunately blew during the final testing stages. This  shed like on how well the sound proofing methods had worked in the construction of the box. To avoid this occurring again, we installed a different fuse that would blow if the speaker was overdriven again.


The Midi Bike

Creating a way to explore free energy as both an interactive and sonic experience was a challenging endeavor.  The concept of creating electrical energy from pure sound energy had been founded. Our prototype worked, and an even more visually impressive concept had been envisioned. Powering 32 LEDs was now the goal. In theory it would work, but how could this be incorporated into an interactive musical experience that would both entertain and impress?

An interactive instrument that could be played easily by the public, creating a challenging, enjoyable and musical path from sound into energy.

This was our goal.

We toyed with ideas of sonic puzzles on MIDI keyboards, or sine wave sweeps to find the “secret” tone to create “free energy.” Even WiiMote controlled music.

Finally a concept was born: a MIDI exercise bicycle.

The bicycle would allow MIDI data to control a sine wave sweep that would trigger the “secret” tone of “free energy.” But how would such an instrument be achieved. The answer: it already had.

Using the MIDI Exercise bike project detailed at the link above as a basis for the project, we began to piece together the required elements.

First we needed an exercise bike that used an inbuilt computer to take readings from a read switch.

A read switch outputs a voltage when a magnet passes within range; this is how the revolutions of the exercise bike’s wheel would be detected and counted.

The bike seen below was used.

Next was the integration of the exercise bike into the computer and as MIDI data.

The key was taking the output of the read switch and interfacing it with an Arduino board. The Arduino board would interpret the voltage from the read switch using on-board coding, outputting midi data to the computer.

The diagram below outlines the schematics for the Arduino, its wiring and integration with MIDI. Further, below an early prototype of our Arduino can be seen. With our prototype Arduino finished and using the same Arduino code from the project above we integrated it with both the exercise bike and computer and hoped to get MIDI data from our pedaling.

We were excited to see that we indeed were getting MIDI data, however it contained glitches. We saw MIDI data being received on a single MIDI message, however random MIDI messages were interrupting the correct data. The image below shows a screenshot of the early MIDI messages being received into the computer.  We were unable to achieve a clean translation of pedaling speed to MIDI data, ranging from the lowest possible parameter (0) to the highest (127). The issue was in the coding and its mathematics.

With modifications made to the coding, we again attempted to integrate our MIDI exercise bike.


We were able to achieve an accurate translation of the pedaling speed of the exercise bike into MIDI data. As the rider pedaled faster the MIDI data would rise from 0 until each reached its peak at 127. As the rider pedaled slower the MIDI data would fall until it stopped at 0

Alterations could be made to the coding to increase the difficulty of reaching 127 in MIDI harder or easier. When decided to make it a challenge for those using the bike. The screenshot below displays our final coding and the maths required to make it work.

This coding is a key component to making the whole project work. The coding interprets voltage data into MIDI data, and employs a smoothing algorithm to create even scaling up in MIDI data from 0 to 127 in relation to pedaling speed. Also, how often a voltage reading is taken scales the speed degree of pedaling required to reach the highest possible MIDI number.

Apart from this element of the project being a success, the rewarding and satisfying element of the project is our ability to improve the coding from the project used as our model. We bettered his coding and hopefully others can use this to created there own interactive MIDI exercise bike.

The Sound

After having a working midi exercise bike, the next step was using it to control some sort of sound.  Based on how we intended the device to work, we needed two sound sources in the installation. One sound would be played to the microphones inside the sound proof box and would not be heard by the user. The other sound would be heard by the user and would vary depending on the speed at which the user was pedaling the midi bike. Our exploration into this began in ProTools where we came up with the simple idea of using a stereo output, with one channel being sent to the box and the other being sent to the speaker which was audible. The next step was to trigger the resonant frequencies into the box, but only when the user was pedaling at a certain level of intensity. This was relatively simple and was accomplished by fine tuning several frequency dependent gates. Having a working concept we then transferred the idea over to Ableton Live which offers more flexibility in terms of midi controlled sound sources.

The first step was to create a small midi loop that would play the same note continuously but would change pitch fluidly when a midi device controlled a pitch wheel.  Our loop lasted for 2 secs.

From there we were able to add plugins such as a pitch shifter and synthesizer effects.

The way it would work was to Midi Map the bike to the pitch shift wheel. The faster the bike was pedaled the higher the pitch, creating a “sweep”. When the sound was at a certain pitch we wanted the resonant frequencies to be triggered in the box. We achieved this by side-chaining the gates from a send from the Sweep and EQing it so that only the higher frequencies would go through. When the pitch was high enough the gates would trigger the resonant frequencies which were on another track and came out the right channel to the box.

The final step was to create a sound source that was pleasing for the user and also incorporated the concept of free energy. Using different synthesizers we managed to put a sound together that also included the sound of electricity and power lines to make it more authentic.

Below is a picture of our the whole installation as it was arranged in the foyer at the Queensland Conservatorium of Music.

Installation in full working order!