Thursday, January 26, 2006

Chancho the goldfish

Saturday, January 21, 2006

Final Presentation

some slides from our final presentation to IDE, which summarize the project up to this point.

design proposal for our space in the IDE Interim Show.

Thursday, January 12, 2006

Microphone evaluation

We attached the piezo buzzer, the Shadow guitar pickup and the piezoelectric film on a window and recorded their response to evaluate their quality.
After the recordings we performed a Fourier spectrum analysis of the sound-data.

Piezo-film analysis:

Piezo-buzzer analysis:

The comparisson shows a better response of the piezo-film, especially in the mid-range frequencies. Second came the guitar with the buzzer last, as expected.

Another factor that we evaluated was the unwanted noise levels picked up by the mics. Again, the piezo-film showed the lowest noise levels compared to the other two.

Monday, January 09, 2006

Microphone+Preamp development

Microphone development from up-left, clockwise:

- Piezo-element used in cheap sound-buzzers. Piezoelectric material is layered on a thin copper substrate. We used the 'inverse' effect of the buzzer, hence mechanical vibtrations are converted to weak electrical signals.
- Small electret-type microphone.
- Acoustic guitar pick-up (Shadow SH711). The piezoelectric element is of higher quality and better shielded against noise.
- Piezo-electric film which offers several advantages, e.g. flexibility

Because of high-impendance and low signal of acoustic pickups, we tried using different pre-amp circuits in order for better recordings. Most of these circuits were taken out of cheap commercial electronics. By trying different configurations of we found out the right choise of pre-amp is crucial to get a clear signal as possible, especially if it is combined with filtering capabilties (EQ).

Microphone-preamp combinations.

During recording, it was evident that external noise was an issue. One factor which infunced that was cables and exposed circuits. We replaced excisting wires with special shielded audio cable.

First tests

This was posted a month ago, but I post it again for reasons of consistency with the next post.

Piezo attached on wall..

Second version with amplifier..

Third version with stronger amplifier..

We attached the piezos on various places around my flat. These include:
- freezer
- thermostat
- radiator
- water pipes
- window
- coffee-maker..

radiator sounds..

the sounds of London from my window..

These sounds were recorded on a computer. Listening to the 'raw' sound files we realized that it is difficult to distinguish the various elements (e.g. flowing water, motors, voices etc.) so we used special software (Sound Studio) to filter through different frequencies..

Unfortunately we haven't found a way yet to upload sounds on the blog..