Emergency whistle

An emergency signalling whistle which simultaneously emits high- and low-pitched whistle tones so as to be detectable from relatively long distances and localizable from relatively short distances. A mouthpiece contains first and second air passages which discharge across openings into chambers of different sizes. The whistle also incorporates cylindrically concave grip surfaces which align with the ends of the person's thumb and forefinger in the grip position. In addition, there is an enlarged flange at the end of the mouthpiece which is retained in the person's mouth by the incisor teeth, and a second flange around the mouthpiece which forms a seal against the outer surface of the person's lips.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to emergency signaling devices, and 
more particularly to a safety whistle which can be blown to help locate a 
person in distress. 
2. Background Art 
Mouth blown whistles are an effective tool for helping to locate a person 
in an emergency. For example, sportsmen are well advised to carry a 
whistle in order to aid searchers in the event they become lost in a 
wilderness or on a body of water. 
Traditional whistles have proven reasonably effective for this purpose. For 
example, the traditional "Thunderer" style whistle, which holds a cork pea 
in a chamber at the end of an air passage, produces a strong, clear note 
with a "warbling" effect which helps draw attention. Nevertheless, these 
traditional devices are not without their deficiencies. 
Firstly, traditional whistles emit only a single tone, which is not ideal 
in many emergency scenarios. For example, it is well known that 
high-pitched tones are generally easier for people to localize, but they 
do not carry well over long distances. Lower-pitched tones by contrast, 
are generally perceptible at longer distances, but it is difficult for the 
human ear to determine the actual location of their source. This 
deficiency can be critical in real world situations: for example, a person 
lost in the woods or on a body of water may initially be a significant 
distance from rescuers, so that a high-pitched tone would not reach them; 
however, when the searchers are closer, higher tones are needed to help 
them localize the source quickly. 
In addition, traditional whistles are not well adapted in terms of 
structure for use in the hostile and often severe environments in which 
emergencies frequently occur. For example, traditional whistles are 
typically meant to be held to the mouth by a hand, but a person who is 
using their arms to stay afloat will be unable to do this. Even if the 
person has their hands free, wet or extreme cold may severely impair their 
ability to grip the device; for example, in severe cold the person will 
either be wearing heavy gloves, which will impair achieving any sort of 
grip, or else their hands will tend to become so numb and stiff as to be 
virtually useless. 
Moreover, hostile environmental conditions may also make it difficult to 
effectively blow air through a whistle. In particular, severe cold and/or 
fatigue can make it very difficult for a person to seal their lips around 
a mouthpiece, with the result that much of the air escapes uselessly. 
Similarly, a person who has been gasping for air, as when trying to stay 
afloat, will find it difficult to hold the device in their mouth, and to 
form an effective seal between breaths. The severity of this problem is 
aggravated by the fact that it is often essential for the person to blow 
the whistle continuously and without interruption if there is to be any 
hope of rescue, as, for example, when a person is lost overboard at night 
or in a fog and therefore cannot know whether rescue boats are near. 
Accordingly, there exists a need for a whistle which can emit tones at both 
high and low pitches, so as to facilitate the detection of persons in 
distress from relatively long distances, and the localization of such 
persons by searchers closer to the scene. Moreover, there is a need for 
such a whistle which is easy to grip with impaired hands, and which may in 
fact be held in the mouth without the aid of one's hands. Still further, 
there exists a need for such a whistle which a a person can correctly 
position in his mouth and form an effective lip seal therewith, even under 
conditions of severe cold, wet, and fatigue. 
SUMMARY OF THE INVENTION 
The present invention has solved the problems cited above, and is an 
emergency signalling whistle comprising a mouthpiece portion configured to 
be gripped in a person's mouth, first and second air passages formed in 
the mouthpiece portion for receiving air which is blown from the person's 
mouth, and means associated with the air passages for simultaneously 
generating (a) a whistle tone having a first pitch in response to passage 
of the air through the first air passage, and (b) a whistle tone having a 
second pitch in response to the passage of the air through the second air 
passage, the first pitch being relatively lower so as to enable the 
whistle to be heard by persons at relatively long distances, and the 
second pitch being relatively higher so as to enable the whistle to be 
localized by persons at relatively short distances. 
The means associated with the air passages for simultaneously generating 
the two whistle tones may comprise an exit slot at an end of each air 
passage, and first and second chambers mounted to the mouthpiece portions 
and having openings across which the air from the exit slots is directed 
so as produce the whistle tones, the first chamber being relatively larger 
so as to produce the relatively lower first pitch, and the second chamber 
being relatively smaller so as to produce the relatively higher second 
pitch. 
The first and second chambers may be generally barrel-shaped and mounted in 
end-to-end relationship at the ends of the air passages, each chamber 
having its opening formed at an edge thereof. There may be a pea member 
received in each chamber for imparting a warbling character to the tone 
which is produced thereby, the pea in the first chamber being sized 
relatively larger than that in the second chamber. 
The mouthpiece portion of the whistle may further comprise a first 
outwardly extending flange portion for forming a substantially airtight 
seal against the outer surface of a person's lips, which flange portion 
may extend annularly completely around the mouthpiece. 
The mouthpiece potion may further comprise a second outwardly extending 
flange portion which is positioned proximate an outer end thereof for 
engaging the inner surfaces of the person's incisor teeth, the second 
flange portion being spaced a predetermined distance from the first such 
that the latter is pressed against the outer surface of the person's lips 
so as to form the seal therewith in response to the second flange portion 
being held in the person's teeth. 
The chambers which are mounted in end-to-end relationship may have outer 
end walls which are configured to be gripped between the person's fingers. 
These may have concave grip surfaces which are generally cylindrically 
dished about axes which extend in roughly vertical directions when the 
mouthpiece is gripped in the person's mouth, so that the cylindrically 
concave grip surfaces are generally aligned with the distal phalanges of 
the thumb and a finger when the whistle is gripped in the person's mouth 
and hand. The grip surfaces may be provided with coarse surface texturing 
for enhancing the grip which is offered thereby.

DETAILED DESCRIPTION 
a. Dual-pitch Structure 
FIG. 1. shows a whistle 10 in accordance with the present invention 
positioned in the mouth of a person 12 so that they can blow through it 
and emit an audible signal. As will be described in greater detail below, 
the whistle simultaneously emits both high- and low-pitched tones which 
enable searchers to first locate it from a relatively long distance, and 
then localize the source as they draw closer. As can be seen in FIGS. 2-3, 
the whistle 10 somewhat resembles a traditional whistle externally, in 
that this comprises generally a drum-shaped body portion 14 from which a 
tapered mouthpiece 16 extends, the body portion also having a forwardly 
projecting loop 18 for receiving a carrying lanyard 20 (see FIG. 1). The 
body portion and mouthpiece portions may be formed unitarily of any 
suitable material, such as injection molded plastic. Furthermore, 
fluorescent, photoluminescent, or reflective materials may be used in the 
construction of the whistle, or decals or labels therefor, so as to 
increase the visibility of the device for the benefit of both the user and 
search personnel. 
By contrast with traditional whistles, however, the interior of whistle 10 
is provided with first and second, side-by-side air passages 22, 24. As 
can be seen in FIG. 5, the air passages preferably taper somewhat, in the 
direction away from the person's mouth. In plan view, however, the air 
passages widen outwardly from the entrance opening, as the overall width 
of the mouthpiece itself increases. 
The air from the person's mouth travels through both air passages and 
escapes through slots 26, 28 at the ends thereof across openings 34, 35 
formed at the edges of chambers 30, 32 so as to produce the desired 
whistle tones. In an exemplary embodiment, a vertical gap of about 0.040" 
has been found to be suitable for the slots 26, 28, with the gap across 
which the air is directed being approximately 0.310" at the top. As will 
be described below, the chambers are preferably oval in shape, with first 
and second radii of about 0.348" and at a spacing of approximately 0.084" 
having been found suitable for the exemplary embodiment. 
Forward ramp portions 36, 37 are formed at the edges of the openings 
opposite slots 26, 28, these being sloped at a suitable angle so as to 
direct a portion of the air flow into the chambers, and there are also 
rearward ramp portions 38, 39 formed above the air slots; a slope of about 
40 degrees and 20 degrees from vertical, respectively, has been found 
suitable for the forward and rearward ramps in a whistle having the 
exemplary dimensions noted above. 
The chambers 30, 32 are generally barrel shaped (i.e., roughly the shape of 
an oval cylinder) so that the air flows along a generally circular or oval 
path therein. Each chamber contains a pea 40, 42, which is formed of cork, 
rubber, plastic, or other suitable material. Thus, as the air is forced 
into the chambers, the peas are caused to rotate past the openings 34, 36, 
imparting a warbling quality to the whistle tones; this warbling or 
"staccato" quality is important in emergency situations, because without 
it the sound tends to blend with and be lost in the whistling of the wind. 
The smaller pea 40 imparts a relatively rapid, shrill staccato to the 
higher note, while the larger pea 42 gives the lower note a deeper 
rumbling or "thundering" quality. 
As can be seen in FIG. 2, and also in FIG. 4, the two chambers 30, 32 and 
their respective air passages are sized differently, one being generally 
wider than the other; in the exemplary embodiment having the dimensions 
given above, a first chamber 30 having an internal width of about of 0.40" 
and a second chamber 32 having an internal width of about 0.50" have been 
found suitable. Inasmuch as the chambers are essentially similar in 
cross-section, this difference in width translates to a difference in 
volumes. As a result, the smaller chamber 30 produces a relatively 
higher-pitched tone, while the larger chamber produces a tone having a 
significantly lower pitch. For the reasons discussed above, this 
lower-pitched tone can be detected by people over relatively greater 
distances, while the higher-pitched tone assists them in localizing the 
source. 
As was noted above and as can be seen in FIG. 5, the chambers 30, 32 are 
not precisely circular in cross-section, but are generally oval instead, 
having cupped forward and rearward walls 43, 44. These are configured to 
reflect the sound waves within the chambers, increasing the acoustic 
efficiency thereof and producing a louder blast than would normally be 
produced by a circular chamber under the same conditions. 
The acoustic performance of the whistle is further enhanced by the 
configuration of the end walls 47, 49 of the chambers 30, 32. As will be 
discussed in greater detail below, the outer surfaces of these walls are 
cylindrically concave so as to offer an enhanced grip for the user's 
fingers. Their inner surfaces, in turn, are cylindrically convex, and as 
the peas rotate past these, the shape and effective volume of the acoustic 
chamber vary somewhat, with the result that a relatively full spectrum of 
sound is produced. Also, as the peas pass the "humps" in the walls, the 
width of the air passage is constricted somewhat, so that the brief, 
localized increase in air pressure which develops behind the pea causes it 
to accelerate twice during each rotation through the chamber; in practice, 
it has been found that this makes it possible to achieve a loud, sharp 
staccato note without having to blow as hard as is required with 
traditional designs. Also, the peas tend to bounce off of the "humps" in 
the walls, with the resultant increased rattling of the peas enhancing the 
staccato effect. 
FIGS. 2 and 4 show all of the elements of the lower-pitched side of the 
whistle being sized larger than those on the higher-pitched side. In 
addition to the acoustic benefits, this configuration is advantageous 
because it has been found economical to manufacture the device with a 
simple longitudinal divider wall 45 which is positioned off-center within 
the symmetrical body and mouthpiece to define the two sides of the 
whistle. However, it may be desirable in some embodiments to obtain the 
higher and lower pitches by adjusting the size of certain elements (e.g., 
chamber size) or their positions, while leaving others (e.g., pea size) 
constant. 
b. Enhanced Hand Grip Structure 
By virtue of the end-to-end transverse placement of the dual chambers 30, 
32, as shown in FIG. 2, the barrel shaped body portion 14 of the whistle 
is rendered relatively wide, this alone making it somewhat easier for a 
person to grip the device with a numb or gloved hand. Moreover, the outer 
sidewalls 43, 44 of the body portion 14 are dished-in to form concave grip 
surfaces 46, 48. The grip surfaces are preferably generally 
semi-cylindrical in shape, with respect to axes which extend in roughly 
vertical directions when the device is received in a person's mouth as 
shown in FIG. 1. This configuration is important because it aligns the 
concave grip surfaces 46, 48 with the natural orientation of the distal 
phalanges of the thumb and a finger when the person's hand is curled to 
grip the device and hold it to the person's mouth. This greatly enhances 
the available grip surface and also the ability of a person to apply 
pressure to this with a numb or heavily gloved hand, as compared, for 
example, to a spherically dished surface which tends to be gripped by 
pressure which is applied axially between the fingertips. 
So as to still further enhance the grip which is offered by the device, the 
concave grip surfaces 46, 48 are provided with heavy surface texturing 50. 
In the embodiment which is illustrated in FIG. 3, the surface texturing is 
in a coarse diamond pattern, which not only offers a superior grip, but 
also reduces the problem of clogging by mud or snow. 
c. Mouth Retainer/lip Seal Structure 
As can be seen in FIGS. 2-3, the mouthpiece 16 of the whistle is provided 
with a structure which enhances the ability of a person to establish an 
effective mouth grip and lip seal therewith. In particular, there is a 
relatively large retainer flange 56 which extends around the end of the 
mouthpiece, and a somewhat larger lip seal flange 58 which extends around 
the mouthpiece a spaced distance "d" from the retainer flange. 
As can be seen in FIG. 5, the retainer flange 56 is configured to engage 
the inner surfaces of the person's incisors 60, 62, and is sufficiently 
large that the person can retain the whistle in their mouth without the 
aid of their hands, even if their jaws are somewhat slack or partially 
open from fatigue or heavy breathing. This is to be contrasted with 
traditional whistle designs which are intended to be gripped in the mouth 
(if at all) by keeping a firm bite on the mouthpiece, which is simply not 
possible for persons to maintain over an extended period. 
The lip seal flange 58, in turn, engages the outer surfaces of the upper 
and lower lips 64, 66 so as to form a substantially airtight seal 
therewith, all around the mouthpiece. The spacing "d" between the seal and 
retainer flanges (see FIG. 3) is selected so that, when held in the mouth 
by persons having normally sized and shaped mouth structures, there is a 
slight pressure of the lip seal flange 58 against the outer surfaces of 
the lips so as to enhance the seal. 
The fact that the whistle is thus easily held in the mouth with an 
effective seal being formed against the lips also makes it possible for a 
person to breathe through the device. This is particularly advantageous in 
those situations where it is necessary for the person to blow the whistle 
continuously. Also, if the person is trying to stay afloat in water which 
sometimes passes over his head, the device will prevent the water from 
entering the person's mouth directly, and any water which enters the 
whistle can be cleared simply by blowing through it. 
The annular lip seal flange may vary somewhat in size and shape from that 
which is illustrated, in that in many embodiments it may be somewhat 
larger and may also be contoured to conform to the shape of the person's 
lips. Also, it may desirable in some cases to form the flange of a 
somewhat flexible material so as to further enhance the seal. Still 
further, in some embodiments the flange may extend around the mouthpiece 
in certain areas (e.g., along the top), but not in other areas, depending 
on where it has been determined that there is particular a need to prevent 
air loss. 
Therefore, having described the present invention in its preferred 
embodiments, it will be understood that many changes and variations made 
thereto without departing from the basic spirit thereof. For example, if 
desired, the whistle can be configured to have three or more air passages 
with associated chambers and other elements to provide three or more 
pitches, rather than two which have been illustrated. Also, as was noted 
above, the shape and size of the tooth engagement and lip seal flanges may 
be modified somewhat from those which are shown, as may be desired for a 
particular application. Still further, the whistle may be formed of any of 
a wide range of suitable materials, such as various metals for example. It 
is therefore not intended that the words used to describe the invention 
nor the drawings illustrating the same be limiting thereon; rather, it is 
intended that the invention be limited only by the scope of the following 
claims.