WO2018077800A1

WO2018077800A1 - Acoustic signaling

Info

Publication number: WO2018077800A1
Application number: PCT/EP2017/076999
Authority: WO
Inventors: Peter Perzlmaier; Thomas Hill
Original assignee: Harman Becker Automotive Systems GmbH
Current assignee: Harman Becker Automotive Systems GmbH
Priority date: 2016-10-27
Filing date: 2017-10-23
Publication date: 2018-05-03
Anticipated expiration: 2019-04-27

Abstract

An acoustic signaling system and method include providing a signaling tone signal; processing the signaling tone signal to provide a processed signaling tone signal; and converting the processed signaling tone signal into signaling sound at a listening position. The system and method further include determining a correlation coefficient from a signal representative of the signaling tone signal and a signal representative of the signaling sound, the correlation coefficient being representative of the correlation of the signaling tone signal and the signaling sound; evaluating the correlation coefficient; and outputting a diagnosis signal if the correlation coefficient is below a predetermined threshold.

Description

ACOUSTIC SIGNALING

BACKGROUND

1. Technical Field

[0001] The disclosure relates to a system and method (generally referred to as a "system") for acoustic signaling.

2. Related Art

[0002] Signaling sounds, such as informational, warning or alarm tones, are used in many different types of applications in which one or more recipients need to be put on alert or warned acoustically, e.g., upon detection of danger or emergency situations such as fire, burglary or unauthorized entry, or also when monitoring transit systems, engines or vehicles. Safety systems commonly record specific events with a sensor, and upon evaluation may generate appropriate signaling sounds by way of acoustic signaling systems. Particularly in modern vehicles with a multiplicity of driver assistance systems a multiplicity of informational, warning and alarm tones is generated during vehicle operation. Since vehicle drivers rely on the dependable operation of such driver assistance systems, it is essential that their acoustic signaling systems operate without fail. Therefore, there is a desire for increasing the reliability of acoustic signaling. SUMMARY

[0003] An acoustic signaling system includes a signal source configured to provide a signaling tone signal; a signal processing block configured to process the signaling tone signal to provide a processed signaling tone signal; and an electro-acoustic reproduction block configured to convert the processed signaling tone signal into signaling sound at a listening position. The acoustic signaling system further includes a correlator configured to determine a correlation coefficient from a signal representative of the signaling tone signal and a signal representative of the signaling sound, the correlation coefficient being representative of the correlation of the signaling tone signal and the signaling sound; and a diagnosis block configured to evaluate the correlation coefficient and to output a diagnosis signal if the correlation coefficient is below a predetermined threshold.

[0004] An acoustic signaling method includes providing a signaling tone signal; processing the signaling tone signal to provide a processed signaling tone signal; and converting the processed signaling tone signal into signaling sound at a listening position. The method further includes determining a correlation coefficient from a signal representative of the signaling tone signal and a signal representative of the signaling sound, the correlation coefficient being representative of the correlation of the signaling tone signal and the signaling sound; and evaluating the correlation coefficient and outputting a diagnosis signal if the correlation coefficient is below a predetermined threshold.

[0005] Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following detailed description and appended figures. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The system may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.

[0007] Figure 1 is a schematic diagram illustrating an exemplary acoustic signaling system having a simple monitoring structure;

[0008] Figure 2 is a schematic diagram illustrating another exemplary acoustic signaling system having a complex monitoring structure;

[0009] Figure 3 is a diagram illustrating an exemplary method for monitoring an acoustic signaling system; and [0010] Figure 4 is a schematic diagram illustrating an exemplary cross-correlator. DETAILED DESCRIPTION

[0011] Referring to Figure 1, an exemplary acoustic signaling system includes a signal generation block 101, a signal processing block 102 connected downstream of the signal generation block 101, and a signal reproduction block 103 connected downstream of the signal processing block 102. A cross-correlator block 104 receives, on the one hand, a signaling tone signal x which is an input signal of signal processing block 102, and, on the other hand, a processed signaling tone signal y which is an output signal of signal processing unit 102, or a signal representative of the processed signaling tone signal y. The cross-correlator block 104 determines a correlation coefficient z representative of the degree of correlation between the signaling tone signal x and the processed signaling tone signal y or a signal representative of the processed signaling tone signal y. In the present example, the signaling tone signal x is input into the cross-correlator block 104 together with the processed signaling tone signal y or, alternatively, with a processed signaling tone signal s' which is provided by an acoustic sensor 105. The acoustic sensor 105 picks up signaling sound s that is generated by the signal reproduction block 103 based on the processed signaling signal y, and converts the picked up signaling sound s into the processed signaling tone signal s' both of which are representative of the processed signaling tone signal y and vice versa. The correlation coefficient z from cross-correlator block 104 is input into a diagnosis block 106 which evaluates the cross-correlation coefficient z and outputs a diagnosis signal d if the cross-correlation coefficient z is below a predetermined threshold v. Further, diagnosis block 106 may control, dependent on the correlation coefficient z, at least one of the signal generation block 101 and the signal processing block 102 by way of a control signal c. [0012] The signal generation block 101, e.g., a tone signal generator, provides one or more signaling tone signals and may be triggered with a trigger signal t, which, as the case may be, can also be used to select one of the tone signals. Different signaling tone signals may be used in connection with different alert, warning or emergency situations, for example. Instead of a signal generator any other appropriate signal source may be employed such as a media player, synthesizer, memory with stored sound samples etc. Simple sound generators may include oscillators or multi- vibrators, which generate single frequency tones or multi-frequency tones without or with a certain temporal structure such as modulated tones, on-and-off switched tones, swelling tones, wobbling tones etc.

[0013] The signal processing block 102 may employ any type of signal processing such as, for example, at least one of equalizing the signaling tone signal x, mixing the signaling tone signal x with another signal, controlling the volume of the signaling tone signal (e.g. by way of a controllable amplifier or an attenuator), modulating the signaling tone signal x (e.g., to change or adjust its temporal structure), delaying the signaling tone signal, and limiting the signaling tone signal. The signal generator block 101 as well as the signal processing block 102 may be implemented in at least one of analog hardware, digital hardware, and software executed by a processor.

[0014] The signal reproduction block 103 may include one or more transducers, e.g., loudspeakers, and optionally one or more amplifiers to drive the transducer(s). The signal reproduction block 103 converts the processed signaling tone signals y, which are in the electrical domain, into the signaling sound s which is in the acoustic domain. The signal reproduction block 103 is designed to supply sufficient acoustic energy to a listening position so that the signaling sound is audible at the listening position under normal operating conditions of the signaling system.

[0015] Cross-correlator 104 determines the correlation coefficient z from the signaling tone signal x and the processed signaling tone signal y (alternatively the processed signaling tone signal s'). The correlation may be determined according to the below equations.

For continuous signaling tone signals x(t) and y(t) in the time domain, the cross- correlation represented by ζ(τ) is defined as:

wherein t is a time and τ is a time delay. Similarly, for discrete signaling tone signals x[n] and y[n] in the time domain, the cross-correlation z[m] is defined as: conv[n, m] = z[m] = ^ x[n] - y[n + m] ,

n=-∞ wherein n and m are discrete points in time. For example, the cross-correlation coefficient for continuous signals may be calculated according to: convex, y)

z = ,

σ_χσ_ν wherein σ_χ and a_y are standard deviations. The cross-correlation coefficient z for discrete signals may be calculated accordingly. However, any other appropriate approach or method may be used to calculate, estimate or approximate the correlation between x and y. In the present example, the cross-correlation coefficient may be between and including "1", which represents full correlation, and "0" which means no correlation.

[0016] The acoustic sensor 105 is configured to pick up (total) sound at or in the vicinity of a listening position and may include one or more microphones (e.g., an array of microphones) and optionally appropriate circuitry for evaluating signals provided by the microphone(s) such as, for example, at least one of amplifiers, filters, and beamforming circuits. The microphone(s) may be operated in combination with, e.g., power supplies, preamplifiers, impedance matching circuits, filters, etc.

[0017] Diagnosis block 106 may, for example, compare the correlation coefficient z with the threshold v and, if the correlation coefficient z undercuts the threshold v, the diagnosis signal d, which indicates a malfunction in the acoustic signaling system, is generated. The diagnosis block 106 may further generate the control signal c which may control, to a certain extent, at least one of the signal generator block lOland the signal processing block 102. For example, the diagnosis block 106 may, at least one of, reset at least one of the signal generator block 101 and signal processing block 102, retrigger (restart) the signal generator block 101, and adjust an equalizer setting and/or a volume setting in the signal processing block 102. The diagnosis block 106 may perform further diagnostic functions on a sporadic or regular basis. Further exemplary diagnostic functions are described below in connection with Figure 2. [0018] Referring now to Figure 2, another exemplary acoustic signaling system includes a signal source, e.g., an audio player block 201, which receives from a memory block 202 audio files to be played, initiated and controlled by a control block 203. The control block 203 receives via a control and/or data bus CAN (e.g., a CAN bus) instructions which are processed by the control block 203 in order to generate a control signal M ctr for the memory block 202, a control signal AP ctr for the audio player block 201, and other control signals as described further below.

[0019] The audio player block 201 may reproduce any appropriate audio file such as, for example, WAV files, MP3 files, AAC files, PCM files, etc. The audio files that are to be played and that are stored in the memory 202 are sent to the audio player 201 upon initiation by the control block 203. Further, the control block 203 controls the audio player 201 to receive the selected audio file and to reproduce it. When the selected audio file is to be played, the control block 203 may also adjust, by way of control signals EQ ctr, (filter) settings of an equalizer block 204 connected downstream of the audio player 201. The control block 203 may further control, by way of a control signal V ctr, a volume control block 205 which is connected downstream of the equalizer block 204 and which may attenuate or amplify signals received from the equalizer block 204. Signals output by the volume control block 205 are supplied to an audio mixing block 206 which further receives useful audio signals from a second audio source 213. In the audio mixing block 206, the two signals received are mixed (e.g., summed up) to supply a respective audio signal via an amplifier 207 to a loudspeaker 208. The second audio source 207 may be controlled by the control block 203 and may be an entertainment or navigation system of a vehicle that may provide signals such as traffic messages, route information, etc.

[0020] A correlator block 209 receives the output signal of the volume control block 205 and the output signal of the audio mixing block 206. The correlation block 209, which may perform a cross-correlation operation, issues a correlation coefficient corr coef to a diagnosis block 210. The diagnosis block 210 may further receive instructions via control and/or data bus CAN and provide a control signal C ctr to the control block 203. The diagnosis block 210 may further receive a diagnosis signal CRC diagn from the memory 202, a diagnosis signal AP diagn from the audio player block 201, a diagnosis signal EQ diagn from the equalizer block 204, and a diagnosis signal V diagn from the volume control block 205. Further, the diagnosis block 210 may receive an amplifier diagnosis signal Amp diagn from the amplifier 207, a loudspeaker diagnosis signal Lpr diagn from the loudspeaker 208. If an optional acoustic sensor for picking up (total) sound at or in the vicinity of a listening position, e.g., a microphone 211 and a preamplifier 212, is employed, a microphone diagnosis signal Mic diagn may also be supplied to the diagnosis block 210. Beside the control signal C ctr the diagnosis block 210 may issue a diagnostic trouble code DTC which indicates a malfunction of the system and provides an identification of the type of malfunction.

[0021] The diagnosis of the memory 202 may include a cyclic redundancy check (CRC) which may, for example, check whether audio files to be played are corrupted. The diagnosis of the audio player 201 may include determining the status of the audio file, e.g. as in order (OK) or not in order (NOK) at start-up, and may include a playback response check (OK, NOK) during operation of the audio player 201. Further, an equalization check may be performed which may include checking the equalizer status and operability at start-up, and checking the equalizer settings, continuously or on a regular basis, during operation of equalizer block 204. Checking the equalizer settings may include a plausibility check at start-up as well as checking the signal flow version and the audio level received from the audio equalization block 204 by comparing them against expected versions and levels. An optional check of the volume control block 205 may include a plausibility check of the volume settings at start-up and/or (continuously or on a regular basis) during operation.

[0022] The diagnosis of the amplifier 207 may include a continuous check of the power supply of the amplifier, and monitoring the output of the amplifier 207. For example, diagnosis of the loudspeaker 208 may include a direct current (DC) check at start-up and a continued alternating current (AC) check during operation to detect, e.g., a line break or a short circuit. If the optional microphone 211 in connection with the preamplifier 212 is employed, a respective diagnosis may be performed, which may include a DC microphone check once at start-up and an AC check continuously or on a regular basis during operation. [0023] The correlation coefficient Corr coef determined by the correlator block 209 may be compared with at least one threshold value in diagnosis block 210. For example, the correlation coefficient Corr coef may be verified against two threshold values, a minimum correlation threshold Corr min and a maximum correlation threshold Corr max. The correlation coefficient Corr Coef may be determined, e.g., calculated, after the respective audio file has been completely played. The two thresholds Corr min and Corr max define a valid range within which the correlation coefficient Corr coef should be during normal operation. The range may be adjustable or fixed. The diagnosis block 210 evaluates the results of each particular diagnosis process and issues the diagnostic trouble code DTC that indicates and optionally identifies a malfunction. Further, based on the results of the particular tests, the diagnosis block 210 may generate the control signal C ctr which may control, via the control block 203, the audio player block 201, the memory block 202, the equalizer block 204, and the volume control block 205.

[0024] In an exemplary acoustic signaling method a signaling tone signal is provided (procedure 301) and the signaling tone signal is processed to provide a processed signaling tone signal (procedure 302). The processed signaling tone signal is converted into signaling sound at a listening position (procedure 303). Further, a correlation coefficient is determined from a signal representative of the signaling tone signal and a signal representative of the signaling sound (procedure 304), wherein the correlation coefficient is representative of the correlation of the signaling tone signal and the signaling sound. The correlation coefficient is evaluated in order to output a diagnosis signal if the correlation coefficient is below a predetermined threshold (procedure 305), i.e., if there is little or no correlation.

[0025] One option is to use the processed signaling tone signal as a signal representative of the signaling sound. In another option, sound may be picked up at or in the vicinity of the listening position and converted into a (total) sound signal which can be used as the signal representative of the signaling sound. Further, at least one of signaling tone signal and processed signaling tone signal may be controlled dependent on the correlation coefficient. Signal processing may include combining the signaling tone signal and a useful signal and/or may include controlling volume by attenuating the signaling tone signal dependent on a volume control signal. Controlling the volume may be dependent on the total sound signal, and may further include checking initially, repeatedly or continuously at least one of converting the processed signaling tone signal into signaling sound, picking up sound, providing the signaling tone signal, and signal processing. Determining the correlation coefficient may further include performing a cross-correlation calculation. The signal representative of the processed signaling tone signal may be derived from the total sound signal or from the processed signaling tone.

[0026] Referring to Figure 4, an exemplary structure of a simple cross-correlator block includes a delay line 401 that is formed by a multiplicity of series-connected delays 402, each having a delay time τ. The delay line 401 is supplied with one input signal, e.g., signal x(t) or y(t), and includes taps between the delays 402, at the beginning of the delay line 401 and at the end of the delay line 401 to provide a multiplicity of tap signals. Each tap signal is multiplied with another input signal, e.g., signal y(t) or x(t), by way of a multiplicity of multipliers 403 to provide a multiplicity of intermediate signals which are summed up by a summer 404 to form a sum signal. The sum signal is weighted (multiplied) in a multiplier 405 with a coefficient K which may be, for example, 1/σ_χ·σ_γ. The output signal of the multiplier 405 is the correlation coefficient z.

[0027] The exemplary systems and methods described above in connection with Figures 1-4 may be used in a variety of applications such as, e.g., automotive applications in which a reliable acoustic signaling is vital. For example, the exemplary systems and methods may be employed to alert a driver of when an autonomous cruise control (ACC) system or any other safety-relevant system including an advanced driver assistance system (ADAS) has become unavailable or issues an alarm.

[0028] The description of embodiments has been presented for purposes of illustration and description. Suitable modifications and variations to the embodiments may be performed in light of the above description or may be acquired from practicing the methods. For example, unless otherwise noted, one or more of the described methods may be performed by a suitable device and/or combination of devices. The described methods and associated actions may also be performed in various orders in addition to the order described in this application, in parallel, and/or simultaneously. The described systems are exemplary in nature, and may include additional elements and/or omit elements. [0029] As used in this application, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural of said elements or steps, unless such exclusion is stated. Furthermore, references to "one embodiment" or "one example" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

[0030] While various embodiments of the invention have been described, it will be apparent to those of ordinary skilled in the art that many more embodiments and implementations are possible within the scope of the invention. In particular, the skilled person will recognize the interchangeability of various features from different embodiments. Although these techniques and systems have been disclosed in the context of certain embodiments and examples, it will be understood that these techniques and systems may be extended beyond the specifically disclosed embodiments to other embodiments and/or uses and obvious modifications thereof.

Claims

CLAIMS:

1. An acoustic signaling system comprising:

a signal source configured to provide a signaling tone signal;

a signal processing block configured to process the signaling tone signal to provide a processed signaling tone signal;

an electro-acoustic reproduction block configured to convert the processed signaling tone signal into signaling sound at a listening position;

a correlator configured to determine a correlation coefficient from a signal representative of the signaling tone signal and a signal representative of the signaling sound, the correlation coefficient being representative of the correlation of the signaling tone signal and the signaling sound; and

a diagnosis block configured to evaluate the correlation coefficient and to output a diagnosis signal if the correlation coefficient is below a predetermined threshold.

2. The system of claim 1, further comprising a sound sensor configured to pick up sound at or in the vicinity of the listening position and to provide a total sound signal.

3. The system of claim 1 or 2, wherein the diagnosis block is further configured to control at least one of signal source and signal processing block dependent on the correlation coefficient.

4. The system of any of claims 1-3, wherein the signal processing block comprises a signal mixer that is configured to combine the signaling tone signal and a useful signal.

5. The system of any of claims 1-4, wherein the signal processing block comprises a volume control configured to attenuate the signaling tone signal dependent on a volume control signal.

6. The system of claim 5, wherein volume control is dependent on the total sound signal.

7. The system of any of claims 1-6, wherein the diagnosis block is further configured to check initially, repeatedly or continuously at least one of electro-acoustic reproduction block, sound sensor, signal source and signal processing block.

8. The system of any of claims 1-7, wherein the correlator is further configured to perform a cross-correlation to determine the correlation coefficient.

9. The system of any of claims 2-8, wherein the signal representative of the processed signaling tone signal is derived from the total sound signal.

10. The system of any of claims 2-8, wherein the signal representative of the processed signaling tone signal is derived from the processed signaling tone.

11. An acoustic signaling method comprising:

providing a signaling tone signal;

processing the signaling tone signal to provide a processed signaling tone signal; converting the processed signaling tone signal into signaling sound at a listening position;

determining a correlation coefficient from a signal representative of the signaling tone signal and a signal representative of the signaling sound, the correlation coefficient being representative of the correlation of the signaling tone signal and the signaling sound; and

evaluating the correlation coefficient and to output a diagnosis signal if the correlation coefficient is below a predetermined threshold.

12. The method of claim 11, further comprising picking up sound at or in the vicinity of the listening position and providing a total sound signal.

13. The method of claim 11 or 12, further comprising controlling at least one of signaling tone signal and processed signaling tone signal dependent on the correlation coefficient.

14. The method of any of claims 11-13, wherein signal processing comprises combining the signaling tone signal and a useful signal.

15. The method of any of claims 11-14, wherein signal processing comprises controlling volume by attenuating the signaling tone signal dependent on a volume control signal.

16. The method of claim 15, wherein controlling volume is dependent on the total sound signal.

17. The method of any of claims 11-16, wherein controlling volume further comprises checking initially, repeatedly or continuously at least one of converting the processed signaling tone signal into signaling sound, picking up sound, providing the signaling tone signal, and signal processing.

18. The method of any of claims 11-17, wherein determining the correlation coefficient further comprises performing a cross-correlation.

19. The method of any of claims 12-18, wherein the signal representative of the processed signaling tone signal is derived from the total sound signal.

20. The method of any of claims 12-18, wherein the signal representative of the processed signaling tone signal is derived from the processed signaling tone.