Noise reduction methods and apparatuses for breathing apparatuses and helmets

Noise reduction in face masks and helmets reduces ear damage and improves communication by reducing noise in demand regulators with air diffuser perforated plates, screens or open cell foam and by providing muffling chambers. Insertable earmuffs are slid into voids formed in interior padding. Oral-nasal masks are isolated from helmet padding. Various layered helmets shells and padding reduce internal noise.

BACKGROUND OF THE INVENTION

Divers can take on a wide range of tasks; underwater search and rescue, reconnaissance and salvage, demolition and construction, research or recreation. These tasks are complicated by the wide variety of conditions that they may be faced from shallow coastal tropical water and freshwater estuaries to deep ocean, arctic and ice covered ocean and timeframes that may be measured from minutes to days in the case of deep submergence and saturation diving as well as the desire to utilize communication systems.

Studies have shown that the difficulties of operating in these hazardous conditions are exacerbated by high levels of noise from a variety of sources both above and below the surface of sufficiently high intensity as to cause auditory damage. Typical sources in the divers' working environment might be blasts due to demolitions or repetitive noises due to underwater tools. In addition, self-generated noise such as airflow through a demand-regulator or the free flow air train can produce unacceptably noisy conditions. Divers are routinely exposed to a range of noise sources of sufficiently high intensity to cause auditory damage. Damage can be caused by high intensity short term exposure, but long-term exposure to levels exceeding 85 dB will cause hearing loss as well. Sources of damaging noise include:self-generated breathing/helmet noiseambient dive-site noisetool noise

All of these sources depend on the environment and/or the diver responses. Even the self-generated breathing noise is impacted by the exertion level of the diver and can rise to damaging noise levels if physical activity and air demand are high. Acoustic levels of communications must exceed all background noise levels to be effective. Communications can actually produce more damage than other noise sources. Reducing other noise sources is critical to overall diver helmet sound levels. Some of these noise sources are common in self contained breathing apparatus (SCBA) and abrasive blasting hoods as well.

Needs exist for improved noise reduction and improved communication in helmets and SCBA and other breathing devices. Pilots and other helmet wearers would be benefited by improved noise reduction and communication in helmets.

SUMMARY OF THE INVENTION

The invention provides methods and apparatus for reducing noise in helmets, masks and SCBA, including those that use air supplies. Reducing noise sources allows communication levels to be reduced to safe levels. The invention reduces noise by reducing both self-generated and external noise via a series of modifications to dive helmets and respirator/regulators and components. New methods and apparatus include:modifying of secondary regulators (demand regulators) to reduce valve-generated noise without increasing diver breathing resistance levels, while improving communications,creating free-flow air train to reduce valve noise and other aerodynamically generated noise,isolating and dampening oral-nasal masks to reduce noise transmission to oral-nasal mask microphones and reduce mask vibrations,incorporating slide-in earmuffs in helmets to isolate helmet volume from ears,modifying helmet structure to reduce environmental transmission into helmetIdentifying digital communications technology for integration into dive communications system
The key features are:Modular upgrade-kit form factor allows application to existing helmets and SCBA's.Reduces breathing noise from secondary regulator (demand regulator) without increasing diver breathing resistanceReduces breathing noise picked up on communications systemsReduces noise from free-flow air trainReduces free-flow air train noise picked up on communications systemsIncorporates slide-in modular earmuffs into modified modular hood/head cushion to isolate ears from helmet cavityModular oral-nasal mask dampener/isolator reduces vibrations in the oral-nasal mask from talking and isolates microphone from the rest of the helmet, reducing noise on the communications systemReduces noise transmitted from externally generated noise sources over existing helmet shell designs using an alternative external shell design.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1shows an example of a commercial dive helmet30improved with aspects of the current invention with a modified free-flow air train10above mask view port9, alternative shell structure helmet construction12, oral-nasal mask dampening jacket11, integrated slide-in earmuffs13, and a modified demand regulator40. The redesigned free-flow air train10reduces free-flow noise. The new oral-nasal mask damping jacket11isolates the internal microphone from noise inside the helmet and reduces silicone mask speech vibration noise. The new alternative helmet shell design12can reduce external noise transmission. Integrated slide-in earmuffs13reduce required communication volume. Redesigned demand regulator40significantly reduces noise with no increase in breathing resistance.

FIG. 2shows a prior art helmet30fromFIG. 1where a secondary regulator valve orifice body15is located to the side of the main helmet assembly30. The demand regulator valve18on dive helmet30operates by opening this spring-loaded valve17using inhalation-induced pressure drop over a diaphragm. The valve18consists of cylindrical body15with a circular orifice on one end and a rubber-covered flat surface17on the other end. Air comes from a high-pressure source through the valve18into the lower pressure volume of the demand regulator14and into the helmet. As air moves from the high pressure to low pressure volumes in cylindrical body15, the conical reducer16and through the orifice, sound is generated from turbulent air fluctuations at the valve opening, and the sounds propagate through the regulator housing and into the oral-nasal mask.

FIG. 3shows various noise-reducing air flow diffusers and filters made of screen20porous sintered metal21and open cell foam22that are representative of small-pore flow restricting elements that are used in the current invention.

FIG. 4shows an embodiment of the current invention that quiets noise in secondary regulators, for example. In this embodiment a sintered stainless steel filter element or other porous flow restricting mechanism and a settling chamber cavity28volume are incorporated into the valve body14. The stock valve seat18is used, but air coming from the open valve is directed through a co-axial sintered metal or other porous flow restricting element20and into a settling chamber28before venting into the main housing.

FIG. 5shows a stock picture of a demand regulator on the left alongside a picture on the right of the quiet modified demand regulator29containing the valve/silencer installed on an oral nasal mask14of a helmet30.

FIG. 6shows a modified increased volume regulator assembly40. Further reductions in noise from the secondary demand regulator were obtained by modifying and fabricating an integrated assembly with a larger volume regulator body40. In this embodiment, the valve muffler assembly29is integrated into a modified demand regulator body40. New regulator40has a sintered silencer in a first muffling cavity28and a second muffling cavity42. The effect is that more sound transmission loss is achieved.

FIG. 7shows an example dive helmet30with an integrated manufactured increased volume regulator40.

FIG. 9shows a stock air train50connected to a dive helmet30.

FIG. 10shows a constant flow air train50with an adjustment valve51and a new orifice plate21and silencing chamber41.

FIG. 11shows a constant flow air train with an adjustment valve and a new cylindrical air diffusing screen20and a silencing muffler chamber41.

FIG. 12shows continuous air flow through an adjustment valve51, a distribution channel cavity52, air diffusion screens20and a silencing and concentrating chamber53, in cross-sectional side, perspective and end views.

FIG. 13shows a prior art air demand valve18with noise causing eddies19.

FIG. 14shows a prior art air demand valve18with a new air diffusing plate21and a muffling or silencing cavity28.

FIG. 15shows a prior art air demand valve18with a new air diffusing screen20and a muffling or silencing cavity28.

FIG. 16shows a prior art air demand valve18with a new air diffusing cylindrical porous plate21with a cylindrical screen20which may contain or open cell porous insert22and a muffling or silencing cavity28.

FIG. 17shows a continuous air flow train50through an adjustment valve51, cylindrical screen20, plate or open cell porous insert and a silencing cavity41and through a hose59to the top of a helmet30to direct air toward a view plate9.

FIG. 18shows an embodiment of a modified secondary regulator (demand regulator) with a diaphragm70actuated valve75, a porous plate or diffusion element77, a settling and muffling cavity79and a port71for silenced air to enter the breathing mask.

FIG. 19shows the stock padding54inside a dive helmet30and a depiction of a modified helmet padding55with ear muff cups13, separated from the overall padding. Changes in padding makeup can improve acoustic damping within the helmet. As supplied, the dive helmet30is well padded, although the padding54exists primarily for the comfort of the diver. The padding54has been modified by creating earmuff cups13separated from the overall padding55, reducing the resonant volume around the ears and isolating them from helmet noise created by the communications system. Earphones74are mounted in the earmuffs that are separate from the padding.

FIG. 20shows an example of an earmuff cup assembly13including padding arches56, backs57to the ear cups and neck foam58. The earmuff13can be designed as a slide-in earmuff such that the helmet30may be easily put on and taken off without stress to the ears. The lower neck foam section58of the new hood cushion55helps form the lower boundary of the earmuff13as the neck dam assembly58is clamped to the helmet30from below. The new modified helmet padding separates the earmuff assembly from the overall padding for improving communications.

FIG. 21shows an unmodified oral-nasal mask damping jacket11on the right. On the left shows the new modified oral-nasal mask52improvement implemented to reduce self-communication noise. A dampening jacket11that isolates the mask's internal microphone from noise inside the helmet is added to the oral-nasal mask52. The modified oral-nasal mask52with stiffener54reduces silicone mask speech vibration noise.

FIG. 22shows self-contained breathing apparatus (SCBA)70used by fire personnel and oxygen masks72used by pilots. In general, voice communications will be progressively degraded as background noise levels increase. This is a well-documented problem with fire fighters and other first responders that are working in high noise environments and may be wearing a self-contained breathing apparatus. Fighter pilots are prone to this problem as well while wearing oxygen masks. The new quiet demand regulator40will eliminate the regulator inhalation noise, thus improving communications on its own and reducing the requirement of the communications system.