GB2556513B

GB2556513B - Directional acoustic system

Info

Publication number: GB2556513B
Application number: GB1800144.6A
Authority: GB
Inventors: Brandon Jez
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-05
Filing date: 2016-05-31
Publication date: 2019-09-25
Anticipated expiration: 2036-05-31
Also published as: WO2016193706A1; GB2556513A; GB201800144D0; GB201509791D0

Description

DIRECTIONAL ACOUSTIC SYSTEM

This invention relates to a directional acoustic system.

BACKGROUND

There are situations where it is beneficial for people to be able to detect the direction a sound signal or signals are coming from. Examples of such situations include locating the direction of approaching emergency vehicles, locating the position of emergency exits and fire exits in buildings, and exits from modes of transport including trains, airplanes and boats. Sound signals can be used for guiding people through enclosed or open spaces such as industrial complexes in emergency situations and where vision is obscured by smoke fumes or flames or when a person is visually impaired or blind.

Existing emergency and fire exit signage consists of visual information. This is of limited use in situations where the sign is out of line of sight of the observer or where vision is impaired by smoke, fumes or flames. Visual signage is of limited use to people with visual impairments and is of no use to people who are blind.

It is known that it is difficult to detect the direction of approaching emergency vehicles by listening to the sounds emitted by sirens currently in use. This is in part due to the use of a single frequency or a small number of frequencies or swept frequencies and a narrow sound beam. The single and swept frequencies do not convey enough information in a suitable time frame for the listener to readily ascertain the direction these signals are coming from.

The current sirens employ higher frequencies typically between 650Hz and 1600Hz which tend to transmit a narrower beam than lower frequencies. The narrow higher frequency sound beams that the current sirens produce tend to bounce off buildings and other objects. They are reflected without significant noticeable audible attenuation of amplitude or modification of their original frequency. The reflected sound beam is hard to distinguish from the original beam. The current sirens often employ swept frequencies which are continually rising and falling. It is difficult for the human psychoacoustic system to gain directional or other information from such swept signals as there is little time for the auditory system to identify and quantify a particular frequency before that frequency changes by small increments to another frequency. Humans are more adept at perceiving individual frequencies if they have other distinct individual frequencies to relate to rather that a single frequency or swept frequencies being heard in isolation or simply repeated.

In many cases it can appear to pedestrians and motorists that the sound is coming from another direction from where it is being transmitted by the emergency vehicle siren. This occurs when the beam is reflected off a surface in another position to the origin of the sound such as walls or buildings.

This often results in confusion amongst motorists who become unsure of whether to take avoiding action or not. The short rise time of the sound waves currently used in the higher frequency ‘yelp’ and ‘yelp and wail’ sirens known in the art often causes a panic reaction in listeners such as motorists and pedestrians. The yelp siren is believed to cause hearing damage to emergency vehicle drivers.

Sometimes motorists are unsure whether the siren sounds currently used by the emergency services are coming from the left, the right, from the front or behind. This problem is particularly prevalent at junctions and crossroads.

There is sometimes confusion about the term directional. The word directional is often applied to microphones which can be unidirectional meaning that they will pick up sounds from one general direction only or omnidirectional in which they can pick up sounds from all directions. Microphones can be engineered to pick up sounds from specified directions and angles.

The sound signals emitted by current sirens are generally unidirectional over a narrow angle and can be likened to the narrow beam emitted by a spotlight in a theatre. The term omnidirectional can be likened to the all around illumination of light bulbs typically used for illuminating a room.

It can be seen that when an emergency vehicle is approaching a crossroads and projecting a narrow directional beam forwards in the direction it is traveling, vehicles approaching the crossroads at an angle to the direction of travel of the emergency vehicle will have difficulty hearing the siren which projects the sound mainly straight ahead.

This difficulty results in thousands of serious accidents, injuries and fatalities involving emergency service vehicles and ordinary motorists cyclists and pedestrians throughout the world.

The social, personal and financial costs of these accidents is enormous and would be significantly reduced if sirens on emergency vehicles enabled motorists to ascertain the direction of approach of emergency vehicles and motorists could then take appropriate action to allow the emergency vehicles to proceed unhindered.

Such sirens that produce this beneficial effect are referred to as ‘directional’ and are the subject of this present invention. A further limitation of sirens currently used is that they typically emit harsh sounds which in themselves directly creates panic amongst listeners. This is in part because the shape of the sound wave has a very steep rise time i.e. it goes from no sound to maximum sound in a very short period of time.

Furthermore the shape of the sound waves can be very sharp shaped waveforms which consist of a steep rise and a sharp point. Alternatively a narrow rectangular wave is used which has an almost vertical rise time going from zero to maximum output in an extremely short time. The listener’s psychoacoustic system has difficulty dealing with these sounds.

The currently used sirens, such as the yelp siren, consist of repeated intense sound waves which creates tension and stress in the listener. When motorists hear a siren, the stress induced by the sound of the siren generally has two results, the motorists either panic and take inappropriate action, or they freeze and take no action. In either case, the emergency vehicle is hindered in its progress.

High noise levels inside the cab of emergency vehicles when sirens are on causes impaired concentration for the emergency vehicle driver and severely limits the efficacy of verbal and radio communications, putting personnel and the public at higher risk.

Many emergency vehicle drivers suffer significant hearing loss after exposure to current sirens.

Human hearing is better adapted to sinusoidal waves such as music and speech which have a more gradual initial rise time which then steepens in the middle section and flattens towards the top and degenerates in a similar manner.

Current sirens often use high pitch signals which as well as tending to reflect off surfaces also reflects off vehicles and fail to adequately penetrate the body shell, windscreens or side windows. There is a lack of attenuation on reflection which causes these sounds to be transmitted and reflected over a long distance particularly in urban situations where there are buildings or walls on both sides of the road.

Motorists often experience hearing sirens in adjacent roads to where they are driving even though these sirens are of no relevance to them. Motorists will hear many more sirens during the course of their driving than they are required to take avoiding action in response to those sirens. Over time motorists become relatively immune to reacting to the sounds of sirens and do not react until they see the typically blue flashing lights associated with emergency vehicles. In these situations the current sirens have failed as advanced warning devices.

Modem vehicles are well sealed against external sounds and the power of modern entertainment systems can overwhelm the motorists’ perception of approaching sirens.

Some components in motor vehicles create sounds similar to white noise. White noise tends to mask other noises and reduces the listeners’ perception of external sounds. White noise emitters are fitted in open plan offices for the specific purpose of reducing the perceived sounds in the office enabling easier conversation between people at close quarters.

In a vehicle, sounds similar to white noise are produced by the fans and air flow in the air conditioning, climate control and heating systems, thereby further damping down perception of external sounds.

Current sirens are often mounted on the roof of emergency vehicles. In the case of vehicles such as ambulances and fire engines the main part of the sound beam is projected high over the roofs of other vehicles particularly cars and motorcycles.

Alternatively the sirens are mounted within the engine compartment with no direct access to the external environment. This inhibits the sound signal being properly projected towards any traffic which might be obstructing the emergency vehicle.

Sirens within the engine compartment are sometimes mounted facing to the side or pointing towards the road surface. Similar to a light beam these mounting positions severely inhibits projection of the sound signals in the desired direction.

Sirens are typically used in conjunction with flashing lights which are typically blue in colour. The current flashing lights often employ a small number of high intensity light emitting diodes as their light source. These flashing lights suffer from similar disadvantages to the current acoustic sirens in that when viewed directly in front of the light beams it is very intense and at the sides it becomes much less intense.

The light emitting diodes light source used in these lights have a narrow frequency spectrum which makes it difficult for human beings to perceive the distance of the light source. During the daytime the current blue lights can be seen at a distance but can also be swamped and less visible during strong sunlight. At night time the current blue lights are very intense especially when viewed directly ahead. This causes motorists to be distracted by the lights for an extended time period. Emergency vehicles often have a multiplicity of lights of different colours, for example, red, blue and white which can be flashing, simultaneously and serially in various sequences. This confuses the motorist further as to gauging the distance of the light source and creates tension and stress in the motorists’ visual perception and psychological systems. lese light sequences are often flashing in a left to right pattern which is difficult for man beings to follow and judge the distance of. Some emergency vehicles will flash ernative headlights from side to side. This further confuses the motorist because we j used to flashing lights at the extremities of vehicles meaning that the vehicle is ending to turn in that direction. On some emergency vehicles the amber turning •ection indicator lights are housed in the same enclosure as the headlights so that len these headlights are flashing from side to side and the indicator is also flashing to iicate the vehicle is intending to turn in that direction this turn indicator is visually ramped by the intensity of the flashing headlights thereby reducing the effectiveness the turn indicator. This also occurs when the turn indicators are mounted separately proximity to any flashing light or illuminated light on the vehicles. is an object of the present invention to provide a directional acoustic system which ercomes or reduces the drawbacks associated with known products of this type.

'AT EM ENT OF THE INVENTION xording to the present invention there is provided a directional acoustic system, mprising: a directional acoustic system to alert people to emergency vehicles or indicate lergency situations and guide people along escape routes comprising at least four und emitters 1 of different frequencies, which are physically set apart horizontally and rtically Fig 14, at least two of which are above at least two others set below, within closures 2 having at least one opening 7, 9, 11, 13 to direct the sound in a desired rection. > overcome or alleviate these problems, the present invention preferably proposes four more sound emitters set apart in a generally quadrangular, rectilinear or trapezoidal ttem in the generally vertical plane. Any sound emitter may be offset from the rtical in respect of any other unit or offset in the horizontal in respect of any other and tereby a light emitting device or devices are illuminated in direct relationship to the ttem of acoustic outputs. ich sound emitter is fitted inside an enclosure. One or more openings in any part of the closure may direct sounds in desired directions. The spread and amplitude of the sound beams may be controlled by openings in the enclosure. Openings in the enclosures emit frequencies which combine to create further frequencies known as beat frequencies.

Two or more of the sound emitters within enclosures are preferably set apart and mounted above and apart from two or more others and are operated simultaneously and have two different sound frequencies. The lower mounted units are operated simultaneously with each other and have two frequencies lower than the upper units and are operated sequentially in relation to the other emitters.

Lights may be built into or are separate from the enclosures and are operated in coordination with the sequence of acoustic outputs from the system. These lights can be automatically varied in intensity depending on ambient light levels or varied by manual control.

In order to indicate different levels of urgency the duration and amplitude of the sound signals emitted can be varied as well as the duration of any silence between sequentially operated sound signals.

The speed of alternation of the sound signals and the relative amplitude can be increased or decreased to represent varying levels of urgency and where acoustic signals overlap the degree of overlap can be adjusted.

The present invention has the advantage over sirens currently in use such as the yelp and wail in that it provides a number of distinct frequencies and amplitudes projected in a variety of directions enabling the human psychoacoustic system to have enough information to analyse and calculate the direction of origin of the sound signals.

Advantageously, the positioning of the sound emitters, the combination of frequencies and the control of the direction of sounds by the enclosures and openings in the enclosures produce a sound pattern which is able to be located by motorists and pedestrians and observers where the sirens are in a fixed position. The coordination of lights and sounds enhances the perception of the position of the sirens and where sirens are on moving vehicles the perception of speed and direction of approach is enhanced.

Preferably, each sound emitter has a different frequency.

Preferably, any two or more sound emitters are activated simultaneously.

Preferably, any two or more simultaneously activated sound emitters are operated sequentially with any other activated sound emitters.

Preferably, there is a period of no sound signal between any two or more simultaneously activated sound emitters being operated sequentially with any activated sound emitters.

Preferably, there is a period of sound signals overlapping between any two or more simultaneously activated sound emitters being operated sequentially with any activated sound emitter.

Preferably, any two or more simultaneously activated sound emitters are operated sequentially with any two or more simultaneously activated sound emitters.

Preferably, there is a period of no sound signal between any two or more simultaneously activated sound emitters being operated sequentially with any two or more simultaneously activated sound emitters.

Preferably, there is a period of overlapping sound signals between any two or more simultaneously activated sound emitters being operated sequentially with any two or more simultaneously activated sound emitters.

Preferably, three or more sound emitters can be activated simultaneously.

Preferably, three or more sound emitters can be activated sequentially.

Preferably, the sound emitters are mounted externally.

Preferably, the sound emitters can be mounted internally with external outlets connected by piping, tubing, trunking or any sound transmitting medium.

Preferably, the amplitude of the sounds emitted can be varied.

Preferably, the sequence of the sounds emitted can be varied.

Preferably, the cycle times of the sounds emitted can be varied.

Preferably, the duration of the sound outputs of the sound emitters can be varied.

Preferably, acoustic sensors are employed to sample the sound signals emitted by the system. The sound signals are inverted electronically and then transmitted to the vehicle driver and/or occupants in order to reduce or cancel the sound heard inside the vehicle cabin from the locatable acoustic system.

Preferably, white noise is transmitted within the vehicle cabin in order to reduce the perceived level of sound produced by the locatable acoustic system.

Preferably, the sequence of the siren sounds and the sequence of flashing or rotating typically blue, red or white lights employed by emergency vehicles is coordinated to be in direct relationship with the sequence of sound outputs from the locatable acoustic system.

Preferably, there is a light mounted on to the siren housing.

Preferably, there is a light mounted adjacent to the siren housing.

Preferably, there is a light mounted integrally with the siren housing.

Preferably, there is a light mounted integrally with the siren housing shaped to indicate the action required by motorists seeing this light.

Preferably, there is a light or multiplicity of lights mounted integrally with the siren housing shaped to indicate the action required by motorists seeing this light.

Preferably, this light is in the shape of an arrow.

Preferably, the sequence of the siren sounds and the sequence of flashing or rotating typically blue, red, amber or white lights is coordinated to be in direct relationship to the sequence of sound outputs from the locatable acoustic system.

Preferably, when by way of example this light is in the shape of an arrow the arrow is totally lit at any one time.

Preferably, when by way of example, this light is in the shape of an arrow the arrow is lit at different times in different parts of the arrow.

Preferably, when by way of example, this light is in the shape of an arrow and it is lit in whatever manner it is coordinated in direct relationship to the sequence of sound outputs from the locatable acoustic system.

Preferably, the intensity of any lights which are coordinated to be in direct relationship to the sequence of sound outputs from the locatable acoustic system is variable.

Preferably, the intensity of any lights which are coordinated to be in direct relationship to the sequence of sound outputs from the locatable acoustic system is variable in direct relationship to the ambient light intensity.

Preferably, the intensity of any lights which are coordinated to be in direct relationship to the sequence of sound outputs from the locatable acoustic system is automatically variable.

Preferably, the intensity of any lights which are coordinated to be in direct relationship to the sequence of sound outputs from the locatable acoustic system is manually variable.

Preferably the pattern of lights is manually variable.

Preferably the pattern of lights is automatically variable.

Also according to the present invention there is provided a method of projecting acoustic signals from a vehicle or location, comprising the steps of: locating a plurality of sound emitters on the vehicle or location, each of the of sound emitters configured within an enclosure having at least one sound emitting opening, the plurality of sound emitters being spaced apart from each other; and energising each one of the spaced apart sound emitters and emitting a respective acoustic signal, at least one of the respective acoustic signals having a different frequency from neighbouring sound emitters.

It is believed that a directional acoustic system and its method of use in accordance with the present invention at least addresses the problems outlined above.

It will be obvious to those skilled in the art that variations of the present invention are possible and it is intended that the present invention may be used other than as specifically described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 shows a sound emitter 1 within a round tubular enclosure 2 with both ends 9 and 10 open emitting sound signal 3. The sound emitter is shown for clarity but will not be seen through the walls of the tubular enclosure;

Figure 2 shows a sound emitter 1 within a round tubular enclosure 2 with both ends 9 and 10 open and one opening 9 slanted at an angle emitting sound signal 3;

Figure 3 shows four sound emitters within round tubular enclosures 2 fixed with mountings 14 in a rectilinear pattern to a vehicle 4;

Figure 4 shows a sound emitter 1 within a round tubular enclosure 2 with both ends 9 and 10 open and round openings 7 situated on the long side of the enclosure emitting sound signal 3 from opening 9;

Figure 5 shows a sound emitter 1 within a round tubular enclosure 2 with both ends 9 and 10 open and round openings 7 situated on the long side of the enclosure emitting sound and sound signal 3 being emitted from opening 9;

Figure 6 shows a sound emitter 1 within a round tubular enclosure 2 with one end 9 open and that opening slanted at an angle and one end 6 closed and round openings 7 situated on the long side of the enclosure emitting sound signal 3 from opening 9;

Figure 7 shows a sound emitter 1 within a round tubular enclosure 2 with one end open 9 and one end 6 closed and round openings 7 situated on the long side of the enclosure emitting sound signals 3 and 8 from openings 7 and emitting sound signal 3 from opening 9;

Figure 8 shows two sound emitters 1 within round tubular enclosures 2 with one end 9 open and one end 6 closed and round openings 7 and tubular opening 7A situated on the long side of the enclosure emitting sound signals 3 and 8 from opening 9 and sound signals 3 and 8 and 8A from openings 7. The skilled person will appreciate that the representation of sound signals are omitted for clarity in some parts of some drawings but all openings will emit sound signals;

Figure 9 shows a sound emitter 1 within a rectangular tubular enclosure 2 with one end 11 open and one end 12 closed and rectangular openings 13 situated on the long side of the enclosure emitting sound signal 3 from opening 11. The shapes of the enclosure are given by way of example and are not limited to the shapes described and are deemed to include any suitable shapes;

Figure 10 shows two sound emitters 1 within rectangular tubular enclosures 2 with one end 11 open and one end 12 closed and rectangular openings 13 situated on the long side of the enclosure emitting sound signals 3 and 8 from openings 11 and 13;

Figure 11 shows four sound emitters within enclosures 2 mounted by attachments 14 to vehicle 4. Acoustic sensors 18, and lights 21, are attached to enclosures 2. Lights 22 are attached to roof of vehicle 4. Sound emitters 15 emitting sound signals 17 have acoustic sensors 16 mounted on them or attached nearby. Sound emitters 15 are mounted by way of example as headphones on the vehicle driver or mounted within the cabin space. Sound emitter 19 is mounted within the vehicle cabin and emits sound signal 20;

Figure 12 shows a front view of a sound emitter within enclosure 2 having a end cap 23, opening 25, translucent or transparent material 24 lit from behind by light emitting diodes, incandescent bulbs or any other means of illuminating 29, end cap 26 with opening 27 and light emitting diodes, incandescent bulbs or any other means of illuminating 28;

Figure 13 shows a plan view of a sound emitter within enclosure 2 having a end cap 23, opening 25, translucent or transparent material 24 lit from behind by light emitting diodes, incandescent bulbs or any other means 29, end cap 26 with opening 27 and light emitting diodes, incandescent bulbs or any other means of illuminating 28;

Figure 14 shows a front view of vehicle 31 with by way of example combined siren and light units 30 fitted with illuminated arrows 24, all attached to the front of vehicle 31; and

Figure 15 shows a schematic drawing of sound emitter and light units 32, 33, 34 and 35 with pneumatic electrical or other means of power supply 36 and 37 and switching or diverting units 38, 39, 40, 41 and 42.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In Figure 1, a sound generating unit 1 powered by any means including gas, electrical power, electronics, mechanical, manual or other or any means is attached internally to enclosure 2 which is made of metal, plastic, glass reinforced plastic, carbon fibre or any suitable material attached by brackets, bolts, bonding agents, welding or other or any means.

When the sound emitter 1 is activated a sound signal 3 is emitted through opening 9. The enclosure 2 controls the spread and direction of the sound signal.

In Figure 2, the enclosure 2 has a slanted opening 9 emitting a sound signal 3 at an angle from the central axis of the enclosure. The enclosure 2 modifies the spread and direction of the sound signal.

Figure 3 shows four sound generating units within enclosures 2 rigidly or flexibly attached to motor vehicle 4 by suitable means 14 including, but not excluding other methods, bolts, brackets, anti-vibration mountings or snap off mountings to reduce damage in the event of collision involving the enclosed sound producing units in which case, for example, a leash or gas supply hose or electrical supply cable might be provided in such a manner as to act as a retaining means to keep the unit 1 attached to the vehicle 4.

Figures 4 and 5 shows the sound generating units 1 within enclosures 2 having a number of various sized openings 7 positioned at various locations to direct sound out of these openings in desired directions along with sound signal 3 being emitted from opening 9.

Figure 6 shows the sound generating unit 1 within enclosure 2 with one end 6 closed and the other sloping end 9 emitting sound signal 3 in a desired direction while blocking the signal from being emitted rearwards by the closed end 6.

Figure 7 shows the sound generating unit 1 within enclosure 2 having an opening at one end 9 emitting sound signal 3 and closed at the other end 6 by a plate, plug or other means and has various openings 7 which emit sound signals 3 and 8.

Where a number of sound signals 3 emitted from openings 7 combine with each other, further sound signals 8 are produced. When the sound signals 3 emitted from various openings 7 and 9 are of different frequencies and combine with each other another frequency 8 known as a beat frequency is produced.

Figure 8 shows two sound generating units 1 within enclosures 2 whereby the sound signals 3 emitted from openings 9 combine giving a further signal 8. Where the signals emanating from openings 9 combine with each other are of different frequencies they will produce another beat frequency 8.

In this example, the opening at 7A consists of a tube which will control the direction and spread of the sound signal which is emitted.

The same principle applies to the openings 7 emitting sound signals 3 which when mixed produce further sound signals 8. When two or more sound signals 8 are combined, a further signal 8A is produced.

Typically the frequency of a beat frequency is the difference in frequencies between the two original frequencies from which it is derived.

Looking at Figure 9, it shows the same configuration as Figure 7 except the round tubular enclosure is replaced by a rectangular enclosure 2 and the round openings are replaced with rectangular openings 13. The cross sectional and longitudinal shape and size of the enclosure will affect the shape and spread of the sound beams 3 emanating from opening 11.

Figure 10 shows a top view of the same general configuration as Figure 9 with rectangular enclosure 2 and rectangular open end 11 emitting sound signals 3 and 8 with rectangular openings 13 along the sides emitting sound signals 3 and 8.

These drawings are by way of example only and the shapes are by way of example also. The cross-section and longitudinal shape of the enclosures can be varied as can be the sizes, shapes and position of the openings.

Figure 11 shows an example of a number of preferred embodiments combined and fitted to a vehicle. The position of the sound generating units is such that the sound will travel along each side of vehicles in front. In this example the height of the upper and lower sound generating units is set so that the maximum sound signal is approximately at the level of the heads of motor car drivers with the lower units set below in order to give a large rectangular sound image projected towards drivers in front of the vehicle 4.

It is this combination of frequencies from the openings, which are designed to emit sound signals over a desired beam pattern and direction which when they combine produce further sound signals of differing amplitude and frequency providing the quality of the overall sound signals heard by the listener enabling the listener to detect the general direction from which the sound signals are emanating.

It is proposed that at least two sound generating units within two enclosures are placed with sound emitting openings a minimum horizontal distance apart of 300mm between the vertical centre lines of the sound outlet openings and are positioned for example a minimum vertical distance of 200mm between the horizontal centre lines of the sound outlet openings of a lower set of at least two sound generating units in enclosures placed a distance apart. The upper units are preferably operated simultaneously and are preferably of two different frequencies thereby producing a range of frequencies and amplitudes as already described.

Another set of at least two enclosed sound generating units in enclosures placed a distance apart are positioned at a distance below and are preferably operated simultaneously each producing a different frequency thereby generating the range of frequencies and amplitudes as already described. The upper enclosed sound generating units preferably have higher frequencies than the lower ones.

Typically one set of sound generating units is operated simultaneously with another set of sound generating units operated simultaneously and sequentially with the other units either directly following the previous units’ operation or following the previous units’ operation with a period of silence between them or the sounds of each set of units overlapping each other.

Humans perceive higher frequencies to be physically higher than lower frequencies. When sound producing units with higher frequencies are physically placed a distance above sound producing units emitting lower frequencies the listener could perceive a greater distance apart than that which the sound producing units are actually set apart.

In the example in Figure 3, the upper sound emitting units within enclosures 2 when operated simultaneously and are of different frequencies will emit sound signals 3 and 8, as shown in Figure 8, giving a perception of a band of horizontal sound with peak perception of the sounds being central to each the of sound emitting units and midway between each of them while maintaining the perception of a wide band of sound.

When the lower pair of sound emitting units 2 in Figure 3 are of different frequencies and are operated simultaneously and both are of lower frequencies in relation to the upper sound producing units they will produce a similar horizontal band of sound which will be perceived by the listener to be emanating from a lower physical position.

The greater the difference between the upper frequencies and the lower frequencies, the greater the perception of their distance apart.

When the upper sound emitters are operated simultaneously or sequentially with the lower emitters being operated simultaneously or sequentially, the listener will perceive a rectangular shaped audio image.

By way of example, where the upper sound producing units have a higher frequency they will project in the forward direction to a greater extent than lower frequencies. Where by way of example, the lower sound emitters have lower frequencies these frequencies are more able to penetrate for example vehicles and rooms and walls within buildings.

Equally, the skilled person will appreciate that it is possible to operate one of the pair of upper sound emitters 2 and one of the pair of lower sound emitters 2 simultaneously or sequentially so that instead of projecting a rectangular shaped audio image produced by operating the spaced apart upper and lower sound emitters 2 having different frequencies, a lateral or side-to-side mode or sequence of operation is possible. In this way, for example, both of the upper and lower sound emitters 2 located at the left hand side of the system can be energised simultaneously before energising both of the upper and lower sound emitters 2 located at the right hand side. Various sequences, for example, alternating one of the pair of upper sound emitters and one of the pair of lower sound emitters in an opposing diagonal pattern or sequence can also be envisaged to produce an audible signal which enables listeners to perceive direction. This is also true of embodiments of the invention that utilise combined sound and light emitting units 30 or separate light units 21 that are attached or associated with the sound emitting units 2.

This combination of a range of higher and lower frequencies, the way they combine to produce further frequencies and amplitudes, along with directivity of the sound signals due to the positioning and shape of the openings in the enclosures together produce an overall picture of audible signals enabling listeners to perceive the general direction the sound signals are emanating from. A further benefit of this configuration and manner of producing sound signals lies in the control over the direction and spread of the sound beams emanating from the various openings.

By way of example, sound beams emanating from the forward openings of the enclosed sound generating units will project the peak amplitude of the sound signal directly forward and central in the horizontal and vertical planes.

The portion of the sound signal which spreads at an angle to the centre in an urban situation such as a street will bounce off buildings offset to the centre of the beam. This reflected part of the sound beam will then bounce towards drivers in vehicles in front of the enclosed sound producing unit.

The reflected sound beam will have a different amplitude and frequency compared to the original beam. The listener is able to detect the differences between the original sound beam and the reflected sound beam and thereby is able to perceive further information to assist the listener in determining the original location of the emanating sound beam.

This same principle applies with multiple sound beams. The variety of different sounds is multiplied giving the listener yet further information again as to where the sound is emanating from.

Openings to the side of the enclosure direct the beams to the side of, for example, an approaching emergency vehicle 4 and further assist vehicle drivers approaching to the side of the path of the emergency vehicle 4 to perceive its location.

The same principles can be applied to locating the emergency exits in buildings, modes of transport, industrial complexes, open spaces and for guiding people along a chosen route in any situation. A further embodiment of the invention shown in Figure 11 is the addition of a system of noise reduction or noise canceling. Acoustic sensors 18 are positioned either close to the acoustic emitters 2 or sensors 16 positioned close to loudspeakers 15 or headphones which will be emitting the noise canceling sound 17. The sound signal is then electronically inverted and transmitted via for example headphones or loudspeakers 15 within the vehicle cabin in order to reduce or cancel the sound perceived by the vehicle driver and occupants.

Such a system benefits the emergency vehicle driver significantly in that he or she is able to concentrate more on driving skills and can have the radio communications and verbal communications transmitted directly to the driver by way of headphones or loudspeakers or verbally with a lower level of siren sounds affecting communications.

Alternatively, white noise 20 can similarly be transmitted to the vehicle driver and occupants with loudspeaker 19 in order to reduce the perception of external noise which has penetrated the vehicle cabin and thus improve verbal and radio communications. A further embodiment of the invention has the flashing or rotating lights 21 and 22 in Figure 11 which are typically blue and/or red for the emergency services and amber for non emergency services flashing or rotating in direct relationship to the sequence of the sounds emitted by the locatable acoustic system. Coordinating the light signals with the acoustic signals reinforces both signals and assists the listeners’ perception of both distance and speed of approach.

In the example in Figure 11, the lights 21 are attached to the sound units 2 to maximise the perceptual reinforcement afforded by the synchronization of the acoustic and visual signals.

In order to transmit varying levels of urgency the duration and amplitude of the sound signals emitted can be varied as well as the duration of any silence between sequentially operated sound signals.

Figure 12 presents a preferred embodiment of the invention which shows a front view of a single combined sound and light emitting unit 30 in enclosure 2 combined with a transparent or translucent clear tinted or coloured material 24 illuminated from behind by a light source or sources 29. The end cap 26 is shown with an opening 27 to project sound in a desired direction. Alternatively end cap 26 does not have opening 27. End cap 26 is shown with a transparent or translucent clear, tinted or coloured material 28 illuminated from behind by a light source or sources. Alternatively end cap 6 has no light source.

Figure 13 presents a preferred embodiment of the invention which shows a plan view of a single combined sound and light emitting unit 30 in enclosure 2 combined with a transparent or translucent clear, tinted or coloured material 24 illuminated from behind by a light source or sources 29. The end cap 26 is shown with an opening 27 to project sound in a desired direction. Alternatively end cap 26 does not have opening 27. End cap 26 is shown with a transparent or translucent clear, tinted or coloured material illuminated from behind by a light source or sources. Alternatively end cap 26 does not have transparent or translucent clear, tinted or coloured material 28 illuminated from behind by a light source or sources.

Figure 14 shows a preferred embodiment of the invention comprising six combined sound and light emitting units 30 combined with transparent or translucent clear, tinted or coloured material 24 illuminated from behind by a light source or sources. The positions of each of the six units is illustrative and does not exclude mounting in other positions including the roof, sides and rear of the vehicle. More than six units can be fitted to further enhance the beneficial effects described. A minimum of two units can be fitted and preferably four units are fitted.

Figure 14 shows one embodiment of the invention comprising six units. Where two units are fitted they are fitted with one unit to each side of the centre line of the vehicle.

Where four units are fitted they are fitted with two units to each side of the centre line of the vehicle. Where six units are fitted they are fitted with three units to each side of the centre line of the vehicle.

One embodiment of the invention has further units 30 fitted to the sides of the vehicle. These units can have the flashing lights operating, with or without siren sounds, and flashing in coordination with the siren sounds being transmitted at the front of the vehicle.

One embodiment of the invention has further units 30 fitted to the rear of the vehicle. These units can have the flashing lights operating, with or without siren sounds, and flashing in coordination with the siren sounds being transmitted at the front of the vehicle. A further embodiment is that any number of sirens in any combination or permutation are operated simultaneously or sequentially. A further embodiment is that any number of illuminated sections in any combination or permutation are operated simultaneously or sequentially.

Figure 15 shows a schematic drawing of for example four combined sound emitter and light units 32, 33, 34 and 35 with pneumatic electrical or other means of power supplies 36 and 37 supplying power to switching or diverting units 38, 39, 40, 41 and 42.

Where 38 and 40 are open (i.e. not allowing power through) and 39, 41 and 42 are closed (i.e. allowing power through) power is supplied only to units 32 and 33 which will operate simultaneously.

When 38 and 41 are closed and 39 and 40 are open, power is supplied only to units 34 and 35 which will operate simultaneously.

When either 38 or 39 is closed and 40, 41 and 42 are closed, power is supplied to units 31, 32, 33 and 34 which will operate simultaneously.

When 38 or 39 are closed, and 40, 41 and 42 are closed power is supplied to units 31, 32, 33 and 34, which will operate simultaneously.

The same principle applies to situations where there are less than or more than four units and can be applied to activating any combination or permutation of individual units.

The principles processes and technology previously described can be applied to emergency exits in any situation and can be utilised to guide people through buildings, open spaces and modes of transport in emergency or evacuation situations whether vision is impaired or not and listeners would benefit from the auditory and visual signals both independently and in combination or permutation in order to safely move to a desired location or locations.

The invention is not intended to be limited to the details of the embodiments described herein, which are described by way of example only. Various additions and alternations may be made to the present invention without departing from the scope of the invention. For example, although particular embodiments refer to implementing the present invention in a quadrangular, rectilinear or trapezoidal configuration, this is in no way intended to be limiting as, in use, the present invention can produce a beneficial directional effect when configured using pairs of sound emitting units set apart horizontally and vertically on the vehicle to produce a sound projection signal. It will be understood that features described in relation to any particular embodiment can be featured in combination with other embodiments.

Claims

CLAIMS I CLAIM:

1. A directional acoustic system to alert people to emergency vehicles or indicate emergency situations and guide people along escape routes comprising at least four sound emitters 1 of different frequencies, which are physically set apart horizontally and vertically Fig 14, at least two of which are above at least two others set below, within enclosures

2 having at least one opening 7,9,11,13 to direct the sound in a desired direction 2. A directional acoustic system according to claim 1 in which there are means to alter the duration of activation of each sound emitter.

3. A directional acoustic system according to claim 1 in which there are means to alter the amplitude of each sound emitter.

4. A directional acoustic system according to claim 1 in which there are means to alter the rate of activation of each sound emitter.

5. A directional acoustic system according to claim 1 in which there are means by which / each sound emitter can be activated independently or simultaneously with one or more other sound emitters.

6. A directional acoustic system according to claim 1 whereby there is provided at least one light emitting unit integral to (24) or separate from the enclosures, the light output of which is coordinated with the acoustic output.

7. A directional acoustic system according to claim 4 in which there are means by which the rate of activation of the sound emitters is coordinated with the rate of activation of emitters of visible light.

8. A directional acoustic system according to claim 2 in which there are means by which the duration of activation of the sound emitters is coordinated with the duration of activation of emitters of visible light.

9. A directional acoustic system according to claim 6 in which there are means to alter the intensity of light emitted.

10. A directional acoustic system according to claim 9 in which there are means to alter the intensity of light emitted in relationship to ambient light.

11. A directional acoustic system according to claim 6 in which there are means to control the direction of the emitted light.

12. A directional acoustic system according to claim 1 whereby a vehicle fitted with the system has the means within the system to actively reduce or cancel the sound emitted by the system as would be heard inside the cabin of the vehicle.