The level of noise that pilots must deal with in a private plane or business jet is not only a nuisance and an interference, it can (and does) result in hearing loss. The FAA and US military have studied the effects of too much noise in the cockpit and the results are stunning: permanent hearing loss occurs in about 30% of aviators! The cumulative assault on the cilia in one’s ears is no laughing matter.
Whether the noise is generated by the propeller, the engine’s exhaust or aerodynamic noise, industrial hygienist, Terry Carraway, puts it this way: “An airplane is a noise radiator!” The noise during a typical flight can vary, greatly. Take-off and landing, however, are the loudest moments; and it is during these times when noise levels inside the cabin can reach 105 dB. Long exposure to only 85 dB can cause hearing damage.
Fortunately, there are a number of remedies pilots can utilize to minimize noise in the cockpit; and here are three of them:
The headset industry has made leaps and bounds with its advancements concerning headsets. Brands and designs geared for aviation, abound; and a few of the high-tech improvements include:
- “Digital Adaptive Noise Reduction”, or DANR, tailors the active noise reduction to specific frequencies based on the frequencies sensed by the ear-cup sensor.
- Nine-volt battery powered headsets will go strong for 25 hours with pilot-selectable auto shut-off. Some headsets use rechargeable Sanyo Eneloop batteries that can last a full six months with a full charge.
- ANR technology allows pilots to choose from single-engine, twin-engine or helicopter profiles and fine-tune the noise attentuation to a specified environment.
Most models of aviator headsets have left/right volume controls, frequency equalizers or tone control and Bluetooth to connect a mobile phone.
The first step is to speak with an audiologist to request frequency-specific ear plugs. Cheap foam plugs designed to block out sound need to be tossed since custom plugs are light years ahead of their archaic counterparts. Custom plugs that are equipped with removable sound filters will reduce noise in certain frequencies. These plugs block only harmful frequencies while allowing the pilot to hear normal sounds, loud and clear. Ideally, custom plugs should be used in addition to one’s regular aviation headset which would result in an additional 15 to 20 dB of noise reduction.
Engine/prop noise can be deafening, and practical things can be done inside the plane, itself, to minimize sound. FAA regulations stipulate that attaching foam matting to the engine side of a plane’s cowling is forbidden, but cell-foam matting adhered to the inside part of the windshield valance is acceptable. This intervention would stop the vibration and much of the sound from reaching the windscreen, keeping it from entering the cockpit. An ideal product for a Cessna 182 or similar aircraft, for example, would be ½-inch closed-cell foam matting.
Various sound-absorbing products are on the market; and aircraft part-supply stores sell sound-dampening foam. Most of these types of products are made of polyurethane foam with an aluminum foil on one side and strong adhesive on the other. This allows for minimal time and effort during installation where cutting can be accomplished with a sharp knife.
The quiet that is produced with high-quality insulation is worth its weight in gold! As with any product, it’s important to research the features of various sound-dampening options, making sure the product offers: 1) low density 2) high compressibility 3) non-flammability and 4) moisture-proofing. Insulation materials absorb the airborne sound energy; and sound barriers redirect it away from the cabin.
Since the auditory effects of elevated sound levels in a plane’s cockpit are a real concern, every effort should be taken to combat this issue. NASA has conducted experiments where microphones were placed inside a Cessna 182 to measure sound during various phases of flight. Sound levels were generated between 105 and 109 dB, while noise levels in a Cessna 172S averaged a bit more than 101 dB. Any noise over 85 dB, on a consistent basis, WILL result in some type of permanent hearing loss; so be proactive!