Myth vs Science – Part Two

November 1, 2000

THERE are those who prefer electronic pick-up systems of a particular design when it comes time to amplify a lead pan with microphones that collect ambient noise; using science without any investigation of precisely how it works.

More often than not, the microphone favours certain frequency ranges at the expense of others, dependent on its positioning in relation to the instrument. Seldom are errors corrected from the engineering console during performance, for fear that the fixing of one problem might cause another and worsen the overall sound.

The miking of bands is an even more complex matter, given that the behaviour of the steel differs with the length of the drum skirt, thickness of the playing surface, size of rubber on the pan sticks and several other variables.

The most popular styles of miking the lead pan seems to be the placing of the pick-up either well above the playing surface or directly below it and several soloists swear by their individual choices.

But at last month’s International Conference on the Science and Technology of the Steelpan (ICSTS), Fasil Muddeen and Brian Copeland of the University of the West Indies Department of Computer and Electronic Engineering, came up with findings distinctly different from the popular placement theories. Muddeen, who presented the findings of experiments carried out using a fourths and fifths style of single-tenor pan, concluded that the best place for optimum response to the microphone is neither above or below the playing surface, but may well be at the side of the skirt.

Speaking on The Polar Response of a Tenor Steelpan, Muddeen explained that: “Knowledge of the acoustical radiation pattern (aka the polar response) of a tenor pan is essential for determining the correct position of equipment used to record the instrument.”

Even such fundamental knowledge is certainly not widespread, although pans are being miked at every opportunity and by people who certainly appear to the layman as having the required expertise. You see the engineers, stage-hands and sometimes the virtuosos themselves adjusting the boom or pick-up sphere, as if to satisfy some predetermined calibration. Nor is there an agreed brand or value of microphone for such applications.

Muddeen and Copeland however went to a lot of trouble, constructing a rig to reduce variation in stick impact and vibration and striking the notes through mechanical means to ensure even touch for their study. “We do not have an anechoic chamber (an environment that allows no echo whatsoever) at the University,” Muddeen explained, “so we had to use the next best thing, Cepstrum analysis for echo detection and removal.”

That in itself is useful information, given that the two young Americans who run Panyard Inc in Akron, Ohio; who once bought pans here after Carnival and shipped them back to the US for re-sale, are now fine-tuning their instruments in an anechoic chamber. Even more interesting is the evidence of cooperation by senior scientific authorities. The Akron chamber was designed and constructed by audio engineers from the National Aeronautic and Space Administration (NASA) facility in Florida.

But back to the fledgling research facility at UWI St Augustine. The Muddeen/Copeland experiments set parameters of the tenor pan’s frequency range at 260 Hertz at the low end and 2800 Hertz at the highest note. The notes sampled were C4, F4, F#4, C5 D5 and F5.

“The results indicate that positions close to a horizontal plane through the instrument are richer in frequency components,” Muddeen said, explaining that the second strongest radiation from a struck note, comes from one exactly across the instrument.

“The results also provide enough evidence to support the argument that an alternative method of recording the sound emissions of this instrument is required,” he said.

“We have been positioning microphones for live performance at random. Placing mikes above and below and all this trial and error has its value as a learning experience, but from our experiments, placing the microphone closer to the rim may represent the best positioning, rather than above or below.


Terry-J at I-Level

Trinicenter.com | Pantrinbago.com