I'm hoping you read this before listening, as you won't understand what is going on, otherwise.

What gives Barbershop it's unique sound is a phenomenon called the "Ringing Chord". It is a chord that sounds absolutely right on pitch. How this is achieved has to do with tempering.

Tempering is tuning of each note in the scale. Now, a novice normally thinks that there is only one way to tune a note. But there are actually several ways of doing so.

To understand this you have to understand a bit about harmonics. Imagine a string that has been plucked. it looks like it is vibrating in the middle, and being held on the ends, forming a thin lens like area, if you were to view it under a strobe. This is the fundamental tone of the string.

However, it can, and does, also vibrate with the center of the string being stationary, in two halves. This is the first harmonic, and is an octave higher than the fundamental. It can also vibrate in thirds, the second harmonic, and is an octave and a "fifth" above the fundamental. I put "fifth" in quotation marks for a reason, as you will see later. The third harmonic vibrates in four parts, and is two octaves above, and the fourth harmonic vibrates in five parts, and is two octaves and a "major third" above the fundamental. There are further harmonics above that, but we will stop there.

This is the basis of true tempering. In a particular key, the "do" or tonic of the scale is in a ratio with the "mi" and the "sol" of 4:5:6. This produces a very clear and ringing tone.

However, true tempering has the problem that it can only really work in one key with standard chords. You leave that key without changing the tuning and it sounds out of tune.

For this reason, most pianos and other keyboard instruments use "even tempering" Where each half step of the chromatic scale is higher than the previous step by the 12th root of 2. Why that number? Because when you get to the octave, it comes out to be exactly twice the lower octave. This tuning is off by a few cycles per second from true tempering, a difference that gets lost with a large ensemble of instruments and or voices. It allows the instrument to be played in any key at all, and still sound very good.

However, the resultant chords sound just a bit off to a well trained ear when played. If you listen to the sound file provided, the first chord played is a C major chord with even tempering. Sounds okay, but you can hear the "beats' in it. The second is a C major chord with true tempering. Notice how much clearer the chord is.

Now, as I said, in an ensemble, this difference gets lost. But, in a small group, such as a barbershop quartet, they practice this, training their ears and voices, to get that true tempering, so the chords they hit "ring". To clarify their tones, you will note that they sing with NO vibrato. None. Period. Otherwise, the ringing effect is lost.

This is also the reason why barbershop singing sounds so much better with only four voices, rather than an entire choir of voices. Trying to get that ring is nearly impossible the more voices you put in it.

HOWEVER, training your ear and voice to sing a PRECISE tone in a chord to produce that ring takes practice, practice, practice. Even autotuning doesn't do a perfect job of it, since it tunes them to an even tempering. But a well trained quartet that has been singing together for some time, will produce music that will send chills down your spine.

Thank true tempering for that.