Barbershop music

Please post your comments and suggestions for this article.

Comment by David Hilderman on September 7th, 2010 at 3:28 pm

“The defining characteristic of the barbershop style is the “ringing” chord. This is a name for one specific and well-defined acoustical effect, also referred to as “expanded sound,” “the angel’s voice,” “the fifth voice,” or “the overtone.” (The barbershopper’s “overtone” is not the same as the acoustic physicist’s overtone, which is known as heterodyning).

The physics and psychophysics of the effect are fairly well understood; it occurs when the upper harmonics in the individual voice notes, and the sum and difference frequencies resulting from nonlinear combinations within the ear, reinforce each other at a particular frequency, strengthening it so that it stands out separately above the blended sound. The effect is audible only on certain kinds of chords, and only when all voices are equally rich in harmonics and justly tuned and balanced. It is not heard in chords sounded on keyboard instruments, due to the slight tuning imperfection of the equal-tempered scale.”

I design products that use “just intonation” and achieve this “overtone” and” ringing”. The explanation of why this happens in the article is gibberish. A more correct explanation is as follows:
When barbershop quartets create a dominant 7th chord, the frequency of the notes create the following relationships:
Root = 4/4
3rd = 5/4
5th = 6/4
7th = 7/4

The result of combining the above frequencies is a waveform that is periodic to 1/4 or 2 octaves below the root pitch . When a person hears a periodic waveform within the musical range of frequencies, the pitch associated with that frequency is perceived.
So if the Chord is an A dominant 7th , the frequencies of the notes would be:
Root (A) = 220 Hz
3rd (C#) = 275 Hz
5th (E) = 330 Hz
7th (G) = 385 Hz

When you combine these frequencies, the result is a waveform that is 2 octaves below the root and equals 55 Hz. This also happens to equal the difference in frequency between the adjacent notes in the chord.
What happens is that the singers produce the harmonics of the “undertone”. They could be singing notes with no harmonics at all and the undertone would be produced. In fact if they could somehow sing without harmonics, the undertone would be more pronounced.

Comment by Jennifer Tanabe on August 8th, 2011 at 11:33 am

Thank you for your valuable feedback. The article has been revised to better explain the physics of the “ringing” chord.

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