Unison Tuning: No Spread vs. Spread

In this video I am going to demonstrate unison tuning and the consequences of spreading the tuning, comparing the ideal model with an actual recording made on a real piano. I show the actual waveforms of in-tune unisons with that of spread unisons, and play the actual results of both cases. When the string tunings are spread, we see and hear a null, followed by a rise, followed by another null again, as every half-wave of the difference in frequency between the strings is from waveform cancellation. This rise and fall is psycho-acoustically perceived by some as a desirable effect, as the brain is tricked into thinking it is a ‘bloom’ when it is nothing more than a comeback from a null. The brain is also tricked into thinking it improves sustain power but that is impossible.