Diaphragm Mouth Calls
At first glance, a diaphragm call looks simple. It's just medical-grade tape, an aluminum frame and latex. But this turkey-hunting tool is anything but simple! The many different possible elements, detailed below, become complex when combined. Changing one of these elements — like three reeds versus two, or thin latex versus thick — results in a totally different sound.
Type of Reeds: Latex thickness is the main difference in reeds. Hygienic latex is 3-8/1000th-of-an-inch thick, compared to prophylactic latex which is very thin at 1.5-2.5/1000th-of-an-inch. Thin reeds are higher pitched, clear and require less air to blow. Thick reeds need to be blown harder and generally sound deeper and raspier.
Number of Reeds: A single reed call requires less air to blow and provides a higher pitch. More reeds means a caller needs to blow harder and the more rasp will be created from the call. When making a multiple-reed call, some callmakers will use a mix of thick and thin reeds to give a call a unique sound.
Cuts in Reeds: Removing slices or chunks from the end of a latex reed affects the call's sound. Simple cuts like the straight line "V" cut are common. Specialized cuts, which require removing pieces of latex, such as the "bat wing," "cutter," or "ghost" cuts to deliver diverse sounds. Cuts in latex also impact the call's intended purpose. A "V" cut creates fast yelps, but the "ghost" cut will kee kee easier.
Reed Tension: A call needs tension on the back, front and sides of the latex reeds in order to make sound when they are blown, and this is a key to a call's performance. A call with more tension will generally take more air control and will be higher pitched. A call with less tension will sound deeper and be easier to operate.
Frame Size: Some modern calls feature a compact, "mini" frame to fit smaller pallets. On the flip side, a "stacked" frame helps fit a larger pallet. Callmakers also claim the stacked frame provides more rasp, makes the call easier to break over the second note of a yelp and requires less air to operate.
Tape: Mouth calls have a half-circle of medical tape around the frame to help seal the call to the roof of your mouth. Individuals can cut and shape this tape for better fit and feel, based on their own preferences. However, some manufacturers produce calls with "advanced" tape jobs to help achieve a more comfortable seal. Examples include shaping "tabs" into the backend of the tape; or installing tape that already has a "contoured" oval shape.
Color of Materials: Tape and latex colors make calls look different and help hunters quickly identify them when changing calls. The color itself should not affect the sound a call produces.
Purpose in Design
All mouth calls are crafted with a specific purpose in mind, such as to ability to produce raspy or clear yelps. Read the call's package to find out what type of calling the product is designed for. But remember, a call that works great for your buddy might sound terrible for you. Experiment with different calls and manufacturer brands to see what works best for you.
— J.J. Reich