Homework 1

This assignment uses data on the monthly water level in lake Erie from 1921-1970. I chose this data set (from DataMarket) because there is a lot of variation among the data points -- there's a short periodic pattern (yearly trends) on top of a larger shape (long-term differences in water levels over the course of decades).

I chose to use two oscillators, add a delay, and increase the amount of reverb in order to thicken the texture of the sonification. I also chose to make the lower frequencies loud and the higher ones soft. The results sound pretty eerie (which is quite fitting for the name of the lake)! Here's a 2-minute excerpt of the sonification:

The gain values are squared because "volume" to the human ear corresponds to the sound intensity, which is measured logarithmically in decibels. Mapping gain values linearly would cause us to perceive large changes between small data values and inaudibly small changes between large data values. Squaring the numbers amplifies the differences between values at the high end so that we can hear the change. Similarly, we perceive frequency logarithmically as well -- each octave is double the frequency of the last. Mapping frequencies linearly would cause us to perceive large changes in pitch between the smaller data values, and small changes between large data values. Midi keynums map the frequencies in a way that is exponential but sounds linear to our ears. The update rate determines how fast the data is played back, so if it's increased or decreased significantly, the frequency/amplitude will change faster or slower.