Brief Description
The data I chose to sonify represented the number of sunspots observed per month from the years 1749 to 1983. The number of sunspots increases and decreases over approximately an eleven-year cycle. This can be clearly heard within the data as a cyclic shift between high and low notes.
Links to Files
- Sunspots wav file
- Sunspots Chuck file
- Original Sunspot data file. Zuerich monthly sunspot numbers 1749 - 1983. Source: Andrews & Herzberg (1985). Note that the rows represent years and the columns represent months.
Answers to Assigned Questions
Q:Why are the values for gain squared?
The values are squared because our perception of volume varies on a logarithmic scale. When the values are squared, two low numbers become closer together than two high numbers. This sounds more natural to the human ear.
Q:Why use MIDI keynums for the freq values? What happens if they're mapped linearly, instead?
Our perception of frequency also varies on a logarithmic scale. If the frequency numbers were to increase linearly we would percieve that the pitch increased quickly at first and then 'leveled off' to some degree. Since MIDI pitches take this frequency scale into account, MIDI pitches will always increase linearly with our perception of pitch.
Q:Why use MIDI keynums for the freq values? What happens if they're mapped linearly, instead?
If the update rate is decreased the notes are played back more rapidly, to the extent that they tend to blur together and overlap. If the rate is increased the notes have more space in between them and the data is sonified more slowly. This effect is used within my piece to give the data an expanding and contracting feel.