common people , res publica and bluegrass euphony often boast the classifiable speech sound of the banjo . Twangy , brilliant and almost metallic , the banjo is a stringed instrument but sound nothing like its cousin theguitar , which can be smooth and warm . If you require a side - by - side comparability of how guitar and banjos differ , look no further than the 1972 movie thriller " Deliverance " and the famous " Dueling Banjos " scene , where two character go head to head with their stringed instruments .
Although both instruments look quite similar – stringed , with a bridge deck and a neck – the sounds they give rise are somehow totally different . Why ? The unretentive response is that a banjo ’s string react in a very complex way when plucked . It has to do with acoustic , physicsand the fashion the banjo is craft .
The banjo is basically a drum with a long cervix and string stretch across it , affix at either end . A bridge circuit bear the strings over the brake drum membrane . The brake drum membrane is very thin , usually about 12 thousandths of an in thick . By line , a guitar ’s soundboard is typically about 1/8th of an inch blockheaded , with the bridge append to the board [ source : Hunn ] . When you pluck a banjo chain , the drum resonates and the bridge vibrates , emitting a auditory sensation . A banjo pluckiness is much louder than a guitar gutsiness because the banjo ’s flimsy headland vibrates much more .
A Nobel Prize - winning physicist named David Politzer studied this phenomenon in depth . Politzer believes the twangy , loud banjo speech sound comes from something called frequency transition . you’re able to modulate the frequency of a stringed legal instrument by changing the tension of the train . For object lesson , guitar players modulate the frequency of a chain when they fight it sideways and get that tremolo , or shaking , sound .
The tension of a pick banjo string changes as it vibrates . Because a banjo ’s brake drum is so tenuous , the pluck make the bridge tickle as well . So the tensity of the bowed stringed instrument changes twice : once from the initial pluckiness and then again from the result movement of the bridge . This change in frequency pitch contour is what gives the banjo its bright , twangy sound .
You might be wondering why this does n’t happen with mandolins or other stringed instruments like fiddle , where the bridge and the strings move in bicycle-built-for-two . The answer is pretty simple-minded – it ’s because those instruments are made of thick wood . Their soundboard ( as compare to the tympan / tissue layer of the banjo ) are too heavy to oscillate . In fact , Politzer points out that if you supervene upon the slender metal drum tissue layer of a banjo with woods , it no longer sounds like a banjo .
