learning the ropes

Today we experimented with different strategies for sensing the motion of springs. The first was inspired by electric guitar pickups. I thought we might be able to create an electromagnetic pickup to sense the vibrations in the springs. We tried to create a simple electromagnet out of a nail and some transformer wire…. oh, yes… and a power drill.

We scrapped the pickup idea after measuring the resistance of the coil to be 0 Ohms. I was concerned it might short something out. Shlomit also thought we would have more creative possibilities if we used sensors rather than capturing the sound of the springs directly.

Returning to a previous sensing idea, we experimented with a flex sensors.

Flex sensors are not ideal for our application; they only sense motion in one direction and require a fair amount of deflection in order to produce a useful reading. (note for the future… measurement ranges would be useful for documentation purposes)

We also considered mounting the springs on top of a pair of joystick potentiometers to sense X-Y movement. The miniature potentiometer we tried to use for our prototype was too stiff to yield useful results. We wrapped a copper wire around the dial of the potentiometer, hoping that motion of the springs on our installation mockup would move the potetiometer and generate a varying resistance. No luck.

Another version of the musical speech patch. I spoke with Peter last week about fffb~ and made it work — to some degree.

I ran into trouble finding the frequency bin with the maximum energy. Jonathan Marcus helped me with a solution to that problem using the zl object.

The patch makes some sounds now, but still not what I hoped for. I wanted a patch that would highlight the musicality of recorded speech. I expect it would work better on some voices than others, but so far it just sounds “random.”

• When the .wav file is silent, the patch plays the last frequency in the frequency transform list (to fix, I will need to detect that case and turn off the cycle~ object)
• I tried testing the patch with the cycle~ object as an input, thinking that a pure tone would be a good way to test the patch’s ability to recognize frequencies. As I changed the frequencies of the cycle~ object going into the patch, there were some spots where the pitch detection “blew up” and returned to the highest frequency in my list.
• More experimentation needs to be done with voice recordings to see how they respond. I will post some results soon.

Using the patch
- Enable the DAC
- Click the “open” message to load a file into the sfplay~ object
- Click the “1″ attached the sfplay~ object to start playback
- The following controls modify the output: transform strength, wave volume, and transform volume
- “Transform Strength” controls the scaling of the values coming out of the fffb~. Increasing the transform strength with cause larger numbers to be packed into the frequency bin energy list. This primarily affects the height of the peaks on the multislider display.
- “Wave Volume” and “Transform Volume” adjust the relative sound levels of the original .wav file and the transformed signal. Set transform volume higher than wave volume to emphasize the transformed sound.