By Wade Bourne

It's not a stretch to compare a duck call to a traditional woodwind instrument such as a saxophone or clarinet. Musicians play these instruments by forcing air through a mouthpiece and across a reed, which vibrates to produce sound. Duck calls work in much the same way.

"A duck call is as sensitive and finicky as any musical instrument," says David Gaston, who owns and operates Gaston Custom Calls in Thomasville, Alabama. "Changing any part of a call will alter the sounds it produces. So the call maker's challenge is to make and assemble the parts and tune the call so that it consistently produces notes with the desired pitch and tone."

Gaston makes Arkansas-style calls, the standard design for modern duck calls. These calls have five main parts: a barrel, insert, tone board, reed, and wedge. The barrel is the hollow body of the call into which the caller blows. The insert fits tightly into the barrel. The tone board is the part of the insert that holds the reed, which is anchored in place by a wedge.

According to Gaston, minor changes to the "guts" of a call can dramatically alter its pitch. "Lengthening or shortening the reed the slightest bit will change the sound," he explains. "A longer reed vibrates more slowly and has a lower pitch. Conversely, a shorter reed vibrates more quickly, so the call's pitch is higher."

Changing the thickness of the reed can also affect a call's sound. A thicker reed requires more air to make it vibrate, and produces greater volume. A standard plastic reed is typically .010 inches thick, whereas stouter reeds usually measure .014 inches.

A cork wedge will dry out over time, losing its elasticity and ability to hold the reed tightly against the tone board. "When that happens, the call will lose its crispness," Gaston says. "Callers should replace the cork wedge periodically so the wedge-reed contact will be tight and the call will remain crisp-sounding."

Barrel thickness is another important factor influencing a call's tone. The thicker the barrel, the more vibration it will absorb. This means that a call with a thicker barrel will have a slightly deeper, mellower tone, while a call with a thinner barrel will have a higher, edgier tone. Other factors that contribute to the way a call sounds include the number of reeds (single or double), the diameter of the call's tone channel (where air exits the insert), the length of the tone board, and the tip of the reed's position relative to the slope of the tone board.

In addition, there's the matter of how a particular caller actually blows the call. "Some people blow harder than others. Some folks cup the call with their hand and use their fingers differently. There are many factors that determine what kind of sounds come out the end of a duck call," Gaston says.

Calls made of acrylic typically produce sound that's sharper and louder than those made of wood or polycarbonate. Top-quality acrylic calls have other benefits as well. They are nonporous, whereas wooden calls will absorb moisture and then swell, mainly on the inside of the call. This increases pressure on the insert and changes the tone of the call so that it isn't as sharp as it once was. Overall, acrylic calls are more consistent in the sounds they produce under various hunting conditions.

"If you really want a call specifically geared toward your needs and calling ability,find a custom call maker whose calls you like, and go visit him in his shop," Gaston advises. "Tell him what you're looking for in a call. Let him listen to you blow. Then he can fine-tune a call to your specifications."