Pick a partial above, click its channel in the mixer, or step through partials with the ← → arrow keys. Decay and release times are the time to fall 40 dB. Sustain at −61 dB means no sustain.
In 1897 the American inventor Thaddeus Cahill patented the Telharmonium, one of the first electronic musical instruments. It made its tones with rotating dynamos: spinning, toothed metal wheels that each generated a nearly pure sine wave at one pitch. The most famous version, installed in New York's Telharmonic Hall in 1906, weighed around 200 tons and filled an entire floor. Its music was sent to subscribers over telephone lines, decades before radio broadcasting.
Cahill understood something remarkable for his time: a sine wave on its own sounds plain, but stacking sine waves at whole-number multiples of a note (its harmonics) at different strengths produces different tone colors. Players blended harmonics to imitate the timbre of orchestral instruments. This is additive synthesis, and the Telharmonium did it more than half a century before the term existed.
What the Telharmonium could not do was change each harmonic over time. Real instruments never hold a fixed recipe: in a trumpet note, the upper harmonics arrive a moment after the lower ones; in a plucked string, the high harmonics die away first. In the 1960s, Robert Moog's modular synthesizers made the envelope generator a standard building block, shaping how a sound starts, holds and fades. The four-stage Attack, Decay, Sustain, Release (ADSR) design came from Moog's collaboration with the composer Vladimir Ussachevsky.
TEMPORA combines the two ideas: Cahill's bank of sine waves, with a Moog-style envelope on every sine. Each harmonic gets its own attack, decay, sustain and release, so a sound's spectrum can evolve the way a real instrument's does.
I wanted a tool where students can answer these questions by building sounds themselves, harmonic by harmonic, while seeing and hearing the result.
Daniel Fox is a record producer, engineer and educator based in Massachusetts, USA.
Questions, ideas, or bugs? edulab@wondersmithaudio.com
Choose a partial with the H/In buttons above the graph, by clicking its channel in the mixer, or with the ← → arrow keys. Then set its Attack, Decay, Sustain and Release. The graph shows every partial's envelope at once, with the selected one highlighted. Tick Edit all together to change every partial at once.
Start each one from New. Watch the Analyzer and the Scope as well as listening.
Turn on H1, H3, H5, H7 and H9, with levels of 0, −19, −28, −34 and −38 dB. Flip the phase (Ø) of H3 and H7 and look at the Scope: a triangle wave. Now flip them back. The waveform changes completely, but does the sound?
Set In1 to a ratio of exactly 1 at 0 dB and turn it on alongside H1. Now flip In1's phase. Two identical sine waves, one upside down, cancel each other out completely.
Turn on H1 to H6 at similar levels, then switch H1 off. The lowest frequency is now gone, yet the pitch you hear stays the same. Your ear fills in the fundamental from the pattern of harmonics above it.
Turn on H2, then turn on In1 at the same level and drag its ratio slowly from 2.000 toward 2.010. The two partials pulse against each other, faster as they move further apart.
Turn on H1 to H8, then give each higher harmonic a longer attack than the one below it. Then try the opposite: give each higher harmonic a shorter decay, with no sustain. Same harmonics, very different instruments.
Hold a note and slowly push up the Mod wheel. A small, slow pitch wobble is often the difference between "electronic" and "played."