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The Relationship Between Pitch & Tempo
December 31, 2011 | 5:51 am

The relationship between pitch and tempo is a self evident physical fact when you consider the way vibrating bodies behave:


When one body vibrates it transmits the energy as sound; it sets the surrounding matter around it oscillating in response to the pushing and pulling. A nearby body will start vibrating at the same pitch if it shares properties with the original vibrating string, tone bar, air column… Also bodies that are harmonically related will vibrate as a partial of their length responds in kind*. As a bass player I like the low down sounds: bass notes sound the way they do because their vibrations are slow compared to the sounds of our voices or guitars. The bass's strings are longer and heavier and so take longer to swing back and forth. I love the feeling as the vibrations pass through my body, owing to the physical connection with the instrument. I have learned to be sensitive to the vibrations as I feel a groove on which to play. The beat of the drummer is a frequency too. It is measured in beats per minute instead of "cycles" per second but there is an unmistakable connection as they are both numbers of repeating events over measured time. It makes sense to me to have the drummer playing over an exact number of bass vibrations instead of making the beat fall between vibrations of the bass string. This is not as far fetched as it sounds as the bass notes are on the order of 50 to 100 vibrations per second which is a clearly discernible interval of time for one vibration. That way the two "vibrations", bass and drum, are synchronized in resonance and will tend perpetuate and enhance each other. I believe this to be an important aspect of the "groove" factor. Try this experiment for yourself: play some sort of bass groove such as ||: I V I I V : || and record it at various tempos with or without chords and drums. You will notice a variability of the groove in that some tempos will seem draggy and others rushed. Try to become aware of this factor and find the perfect tempo for the groove by trial and error. This means, then, for every key there is a perfect tempo (several really, multiples of the time will also agree proportionately). The converse is also true then that for every tempo there is a perfect key, other notes will agree too if they have a number relationship, such as members of a chord. Conclusively, if you use this idea of agreement of the tempo and the key of the music in your recordings, you will improve them immeasurably.

*This can be proven by holding down a low C on the piano and hearing the ring of a loud quick high C" as the bass string vibrates in partials**. When things shake in an orderly manner they can split the length of the vibration in 2 –– such as when holding the centre of a plucked guitar string. The sound of strings is especially interesting to me as they decay through the life of the note as the string divides into 2, then 3, then 4 etc. until the energy of the vibration is dissipated.

**press and hold the low note on the piano gently so it makes no sound, then play the high note staccato, stab and release. You will hear that note in the bass string as it is contained there within the sound of that string. The sympathetic resonance of the partials of the string will be audible.

I'd be interested in your opinion or results of the above experiment...

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I spent a good part of my childhood humming just barely off key with the kitchen mixer, vacuum cleaner, piano; listening to the warble and getting the tickle in my brain. The ** experiment I've conducted many times and I have no doubt you're right about tempo too.

But all I have now is a MacBook Pro and an M-Audio Oxygen 49. I am jealous of the physical connection you share with your instrument. At this moment, listening to your tracks, I am indeed supremely jealous.

Mark
Latest Song: The Dead Do Not Mourn
Artist Page Send Message January 9, 2012 | 10:38 pm

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