FIELD OF THE INVENTION

This invention relates to a sound system which creates areas where private conversations can take place.

BACKGROUND OF THE INVENTION

An increasing number of office workers are located nowadays in open plan offices. In such offices, but also in other instances, a common complaint is that people have difficulties in doing their job because of annoying and distracting sounds around them. The most distracting sound source in open plan offices is speech, in particular speech resulting from (informal) meetings of people. The participants to the meeting need to have a high level of speech intelligibility, while other people who are not participating in the meeting are annoyed and distracted by the (unwanted) speech.

Conventional means to reduce the distractions of speech are blocking and/or absorbing the sound with walls between the desks. This can be quite effective, but it destroys the open character of the space and the benefits that this brings with respect to collaboration of people in the open plan office. Distraction by speech may also be reduced by sound masking (adding noise). This preserves the openness of space, but it also raises the general sound level in the office.

The invention aims to provide a system in which the speech intelligibly at the position of the intended listeners is good, while at the same time the annoyance to other people evoked by the (unwanted) speech is as small as possible.

Typically, speech intelligibility is increased by raising the voice to a sufficient level above the background level (the so-called Lombard effect). Thus, the higher the background level, the higher the speech level used in the meeting. Given the radiation characteristics of the human voice, most of this speech sound energy is radiated in the horizontal plane, easily reaching and strongly impacting adjacent office workers. SUMMARY OF THE INVENTION

According to the invention, there is provided a sound system for creating a private sound space, comprising:

a microphone located in the sound space for picking up speech generated by people in the sound space;

a directional speaker for directing an amplified version of the speech picked up by the microphone into the sound space.

This system uses the amplification of the speech of a speaker within the designated sound space, and who is addressing other (informal) meeting members, by using a loudspeaker or loudspeaker array which causes directional radiation of the sound mainly to the people in the sound space. The sound radiated towards people outside the sound space is thereby minimized.

The amplification can include signal processing, to enable people in the sound space to hear each other more clearly. This increases the perception of being in a small space, which increases the feeling of privacy and creates an informal setting.

The amplification allows people to speak more softly, so that the path of sound from the people in the sound space to the neighboring areas is reduced. Thus, the

amplification of the speech content actively causes the speech sound levels to be reduced. Thus, a greater proportion of the sound pressure which is being listened to is directional, from the speaker or speaker array, and less horizontally directed speech output is sent towards others in the vicinity.

This system thus has several advantages over a passive system using reflective or absorbing surfaces.

Firstly, it allows steering the added sound towards the desired directions.

Secondly, the level of added sound radiated via the loudspeakers can be amplified to a higher level than the original speech signal, without negative effects for speech intelligibility. As outlined above, this allows the speaker to actually speak with a lower voice compared to the situation without the system, while maintaining the necessary speech level at the position of the other meeting members. As described above, the speech sounds generated by the human voice are those that are radiated toward the other office workers, and the system thus helps to reduce this sound radiation.

Both these described effects decrease distraction of workers near the sound space while allowing easy communication between meeting members in the sound space. The system also has the advantage over sound masking systems that the overall noise level is reduced rather than increased.

The directional speaker can comprise a multiple speaker array. This improves the options for directional sound control.

The microphone can also comprise a multiple microphone array, which can also be directional.

In a preferred example, the system is integrated into a housing located above the sound space. This can direct sound down to the people in the sound space, and can also function as an indicator to define in an obvious way the location of the sound space.

The directional speaker then preferably comprises a multiple speaker array for improving the confinement of the sound pressure level within a vertical cylinder beneath the housing.

A lighting element can be provided as part of the housing, for lighting the sound space. This further identifies the sound space, and can be arranged to provide a light output which is conducive to a meeting space. A light diffusing film can for example be formed over a lower face of the housing.

A controller can be provided for controlling the lighting in dependence on the speech picked up by the microphone. Thus, the brightness level may react to the volume of speech in the sound space.

The invention also provides a method of creating a private sound space, comprising:

picking up speech generated by people in the sound space;

directing an amplified version of the speech picked up into the sound space.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 shows a system of the invention;

Fig. 2 shows the sound output pressure level from a single speaker;

Fig. 3 shows an example of possible sound output pressure level from a speaker array;

Fig. 4 shows an example of the system of the invention formed as a combined lighting, speaker and microphone housing; and Figs. 5A, 5B and 5C are a perspective view, a cross section and a bottom view of a luminaire design that can incorporate the speakers and microphones to implement the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides a sound system for creating a private sound space. Speech generated by people in the sound space is picked up and amplified, before being sent by a directional speaker into the sound space. By allowing users to speak more softly, the system enables the speech of users in the sound space to be converted from general multidirectional sound (which can easily be overheard) into directional sound into the sound space.

Fig. 1 shows a system of the invention.

A sound space 10 comprises an area where occupiers of the area can converse with each other without being heard by or disturbing other people in the vicinity. For example, the sound space 10 comprises a table 12 where two people 14 are having a discussion. Other people 16 nearby are not disturbed. This is achieved by reducing the volume with which the people 14 need to speak, and providing amplification of their speech in a directional way within the space 10. The system avoids adding masking noise and thereby avoids increasing the overall noise level in the total space.

The system has an overhead unit 18 (a housing) which includes loudspeakers 20, optional lighting 22 and a microphone arrangement 23. The microphone arrangement 23 may be part of the overhead unit 18 or it may be part of the table 12, or it may be a freestanding microphone or set of microphones in the sound space.

The aim of the system is to amplify the speech of people 14 addressing the other (informal) meeting members 14 by using a loudspeaker or loudspeaker array which causes radiation of the sound mainly to people 14, while minimizing the sound radiated towards people 16. The added amplified sound is steered towards the desired directions and the level of added sound radiated via the loudspeakers can be amplified to a higher level than the original speech signal so that the person 14 speaking can speak with a lower voice.

In one example, the overhead unit 18 comprises a dome, with a loudspeaker array integrated in the dome directing the speech received by microphones mounted at the rim of the dome. The sound is directed mainly towards the table 12 suppressing sound radiation in directions away from the table and as such minimizing the annoyance of people 16 who are not sitting or standing in the vicinity of the table. The loudspeaker system can be integrated into a lighting system in order to give various advantages set out below.

The lighting can be inviting to attract people to the position of the system in an intuitive way. People are usually attracted by higher light levels and warmer light. This creates an inviting meeting point in an open plan office, with minimal distraction to other people in the same room. An open informal work space near the work desks is very efficient for collaboration.

The integration of the system into an overhead unit means the loudspeaker system can be installed only at a single or a few points in the room, instead of all over the ceiling.

By analyzing the microphone input, the light effect may react to the speech level and even the speech content at the meeting point. Light level, color temperature, colour, distribution etc. may be adapted to the type of meeting (brainstorm or informal coffee discussion etc.). Alternatively, the lights may slowly start to dim (or start blinking, or give a colored light effect) when the speech becomes too loud, thus giving visual feedback to the speakers in the meeting to lower their voices.

In the version of Fig. 1, a square loudspeaker array is positioned right above the area where the people having a meeting are located. The speech is picked up by microphones and reproduced by the loudspeakers in such a way that the intelligibility is increased (by suitable signal processing to remove noise), while the annoyance for people who are not participating in the conversation is minimized.

Figs. 2 and 3 show the results that can be reached when a loudspeaker array is used to direct the sound field.

Fig. 2 shows the sound pressure level at different distances from a single sound source. Fig. 2 shows the speech spectrum-weighted sound pressure level (dBA) as a function of receiver position, if only one loudspeaker is be used to reproduce the sound field. A so-called "free-field" situation is simulated, i.e., there are no boundaries present which may reflect the sound. The figure, shows a cross-section (x-z plane) of the listening area. In this case, the sound field has a spherical nature, with a decay of 6 dB per distance doubling.

By using beamforming, the speech can be amplified in a specific area or in specific areas, while the sound pressure level at further distances from the array is much lower compared with the case in which only one loudspeaker is used.

Fig. 3 shows the speech spectrum-weighted sound pressure level (dBA) as a function of receiver position for a loudspeaker array with five loudspeakers, which is used to beam the sound field towards the downward z-direction. Figs. 2 and 3 are normalized to the same souond pressure level at the height of a standing person to the side of the housing. Thus, in both figures the sound pressure level is 0 dB at coordinate (0.9, 1.8), and this is point represented as "0" in both figures. This enables easy comparison between the figures.

As can be seen, the sound pressure levels away from the loudspeaker array are much lower compared with the single loudspeaker case, while the sound pressure level in the listening area (position x=0) is greater. For this case, the average decay outside of the area below the device is 11 dB per distance doubling.

A possible setup in which the system is integrated into a light solution is shown in Fig. 4. In this case, the loudspeakers 20 are hidden behind an optical light output window 30. In order to ensure sufficient acoustic transmittance through the optical window, this material is preferably a thin foil material (instead of a hard plastic or glass plate). In a preferred embodiment, the light is diffusely transmitted through a milky stretch (PVC) foil (e.g. Barrisol) or textile, which is conventionally used in stretch ceilings.

Two light sources 22 are shown, but only one is needed, preferably an LED or TL lamp (low pressure mercury discharge fluorescent lamp), or other high intensity discharge lamp. In another embodiment, the light can be transmitted through a foils with optical beam forming structures that produce a more focused (less diffuse) beam.

The back side of the luminaire (behind the light sources) can be either acoustically absorbing (for example foam) or reflecting (for example a hard shell), depending on whether a further passive reduction/enhancement of the local sound level is required.

The sound field is recorded by the microphones 23 mounted in the bottom of the luminaire.

The light source can comprise an array of LEDs spread over the top inner surface of the housing and a MLO (micro lens optic) foil can be used to ensure a diffusing effect and make sure that the light is reduced under large angles. The MLO foil is preferably thin, enabling the transmission of sound.

Fig. 4 also shows a controller 25 which can control the lighting and the loudspeaker output in dependence on conditions detected by the microphones.

As mentioned above, the overhead unit can be designed to reflect or absorb sound. In one example, it has an inner reflector part and an outer sound absorbing part.

Figs. 5 A to 5C are different views of an example of housing design that can be used. The housing is in the form of a luminaire 40 having a rounded triangular dome shape. The housing has a body 42 which is made of sound reflecting material like fiber glass. The body 42 is suspended by means of a cable 43 from a ceiling 44 above a working area. A virtual cylinder 45 is bounded by the periphery of the body 42 and the projection thereof on the working area. The body 42 comprises a ring-shaped sound absorbing element 46 located on a side of the body 42 directed towards the working area and near the periphery 45. The sound absorbing element 46 is made of sound absorbing material. An absorbing material is a substantially open porous material which for example, can be obtained by open porous foam such as PU foam, a packing of fibers such as glasswool or even a basically reflective material with many perforations. Sound is absorbed by pressure fluctuations in these pores. The sound absorbing element 46 can be covered with a relatively thin layer of closed material for design reasons. This thin layer will have no or nearly no effect on the sound absorbing properties of the sound absorbing element 46.

Due to the ring-shaped sound absorbing element 46 located in front of the body 42, only the central region of the body 42 will act as a sound reflecting element.

Projected on the working area, the surface of the sound reflecting element 42 is in the range of 40% to 80%, whilst the surface of the sound absorbing element 46 is in the range of 60%> to 20 %.

The sound reflecting element 42 and the sound absorbing element 46 are reflective/absorbent for speech relevant frequencies of between 200 Hz to 7000 Hz. The absorption by the sound absorbing element 46 will be at least 20% and preferably even more. With a radius of the fixture of about 1.5m, the sound absorbing element 46 may have a width w (se Fig. 5) of about 0.2m.

The housing 40 comprises a circular light diffuser 47. The light diffuser 47 is located inside the ring shaped sound absorbing element 46, thereby hiding the central region of the body 42 from view. The lighting element 22 is located between the sound reflecting element formed by the body 42 and the light diffuser 47. Preferably, the light diffuser 47 has a relatively low density to be transparent for speech relevant frequencies so that sound directed from the working area will either be absorbed by the sound absorbing element 46 or be reflected the sound reflecting material of the central region of the body 42. Similarly, the sound output from the speakers 20 can pass through uninterrupted.

The size of the housing is so that the predetermined number of persons such as between 2 and 10 can sit or stand in or near the virtual cylinder 45 to speak to each other. Near the first person who is speaking the sound of the speech is absorbed by a part of the sound absorbing element 46. However, the others persons will clearly hear the first person since the speech will be reflected by the sound reflecting element towards them. The side of the body 42 directed towards the ceiling 44 can be made of or provided with any kind of material. However, preferably at least one material is chosen which prevents acoustics to travel from above through the body 42 towards the working area.

When people are standing or sitting below the luminaire, the sound reflecting element improves the audio of the speaker to the other persons of the meeting. The sound absorbing element near or on the periphery of the fixture prevents reflections which arrive too early and only result in coloration of the speech. Due to the improved acoustics in the working area below the luminaire, the arrangement further enables people in the meeting to lower their voices without loss of audibility (in addition to the same effect achieved by the signal amplification).

The dome can be conical, rounded square or concave circular for example, instead of the rounded triangular form shown.

Applications of the invention include basically all situations in which speech can act as a major distracter, while the possibility of having a conversation, without annoying other people, should still be possible. This method is in particular intended in combination with lighting facilities, but it can be used with normal ceiling lighting as well.

In open-plan offices, speech from co-workers is the most important source of annoyance and stress. This invention creates a space in the office where private conversation is possible without bothering people around.

Hospitals are generally noisy environments because of noise from the equipment and from talking people. Reducing speech noise, by offering well-defined areas where private conversation at a low speech level is possible, can reduce this problem.

Finally, large halls for conventions or airports are examples of environments where distracting other people is not a large issue. However, because of the noise it is still difficult to have a private conversation. The invention can prove helpful in situations like these.

In the example above, the system is provided as a single housing. This may not be the ideal location for the microphone or microphone array. This may instead be provided in the meeting table, or it may be freestanding, or it may pull down from the overhead unit.

The audio processing that can be used is well known. This can involve control of multiple speakers to obtain a directional output, signal processing to improve the quality of the speech output signal, and control and processing of the microphone signals to extract the signals of interest. Furthermore, the microphones can pick up the amplified speech from the loudspeakers, so that anti-howling electronics can be used to prevent this feedback resulting in howling. This type of audio processing is also well known.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.