JP4496143B2 - Noise measurement device - Google Patents

Description

  The present invention relates to a noise measuring apparatus that measures noise using a microphone array.

  As a conventional method for calibrating a sound level meter, it is known that a sound level meter is manually calibrated after a sound calibrator is attached to a microphone. Therefore, in the calibration in the noise measurement device using the microphone array, the calibration operation must be manually performed on the noise measurement device by the number of microphones while replacing the acoustic calibrators with respect to the plurality of microphones constituting the microphone array.

  However, such a manual manual calibration operation requires a worker to move back and forth between the microphone array and the noise measuring device main body, and is very troublesome.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a noise measuring apparatus in which calibration is automatically performed only by replacing the acoustic calibrator with a microphone. Is to provide.

In order to solve the above-mentioned problem, the invention according to claim 1 is a noise measuring apparatus for measuring noise using a microphone array, wherein the acoustic signal from each microphone of the microphone array is a calibration sound or an environmental sound. identification means for identifying an acoustic signal is provided with a calibration means for automatically calibrating for microphone is identified as a calibration tone by the identification means.

Further, the identification means determines that the sound is a calibration sound when an acoustic signal having a constant sound pressure is input for a predetermined time or more, and the identification means determines that the acoustic signal from any microphone of the microphone array is a calibration sound. When judged, the measurement mode is automatically switched to the calibration mode .

  According to the first aspect of the present invention, since the calibration for the microphone is automatically started only by changing the acoustic calibrator to each microphone constituting the microphone array, the manual calibration operation for the noise measuring device for each microphone is performed. This eliminates the need for calibration, reduces the labor of calibration work, and reduces man-hours.

Further, by using an acoustic signal having a constant sound pressure as the calibration sound, the noise measuring device does not require a special processing means and can be calibrated with a simple configuration.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a block diagram of the noise measuring apparatus according to the present invention, FIG. 2 is a flowchart showing the operation (calibration work) of the noise measuring apparatus, and FIG. 3 is a flowchart showing the operation (measuring work) of the noise measuring apparatus. is there.

  As shown in FIG. 1, the noise measuring apparatus according to the present invention processes a microphone array 1 in which N microphones M1, M2,..., MN are arranged, and output signals from the microphones M1, M2,. It consists of a noise measuring device main body 2. For the calibration of the noise measuring apparatus, an acoustic calibrator 3 that outputs a calibrated acoustic signal (calibration sound) of 1 kHz (frequency) · 94 dB (sound pressure) is used. In the calibration operation, the acoustic calibrator 3 is sequentially attached to the microphones M1, M2,.

  The use of an acoustic signal of 1 kHz (frequency) / 94 dB (sound pressure) as a calibration sound is generally used in the field of noise measurement, and it is generally unlikely that the environmental sound will maintain a certain level. The fact that a single frequency of 1 kHz has a magnitude of 94 dB and continues at a constant level is very low. Note that the frequency / sound pressure may be 250 Hz · 114 dB, or any frequency that is continuously output at a constant frequency and a constant sound pressure. There are also a method using a sound pattern that is unlikely to exist as an environmental sound, and a method of viewing only the level regardless of the frequency.

  The noise measuring device body 2 performs signal processing on N A / D converters 4 that convert analog output signals of the microphones M1, M2,..., MN into digital signals, and output signals of the A / D converters 4. The signal processing unit 5 and a memory 6 that stores the calibration sensitivity obtained by the signal processing unit 5 during calibration in association with the microphones M1, M2,.

  The signal processing unit 5 determines whether the acoustic signal input to the microphones M1, M2,..., MN is a calibration sound or an environmental sound. .., MN for identifying microphones M1, M2,..., MN to which the device 3 is attached, and when the determination result of the identification means 10 is an environmental sound, the noise is measured by performing a normal noise measurement on the environmental sound. When the determination result of the noise measuring means 11 for determining the level and the identification means 10 is a calibration sound, the calibration processing is automatically started based on the calibration sound and the microphones M1, M2,. It is comprised from the calibration means 12 which calculates | requires calibration sensitivity.

The operation (calibration work, measurement work) of the noise measurement apparatus according to the present invention configured as described above will be described with reference to the flowcharts shown in FIGS.
First, when performing the calibration work, as shown in FIG. 2, the acoustic calibrator 3 is attached to one microphone M1 in the microphone array 1 in step SP1. In step SP2, an acoustic signal (calibration sound) of 1 kHz (frequency) · 94 dB (sound pressure) is continuously output (for example, for 3 seconds) from the acoustic calibrator 3. In step SP3, the A / D converter 4 converts the output signals of the microphones M1, M2,..., MN into digital signals.

Next, in step SP4, the identification unit 10 determines that any of the acoustic signals digitized by the A / D converter 4 is a calibration sound. Note that a range for determining a certain level and a duration time can be set. When the identification unit 10 determines that any of the acoustic signals is a calibration sound, the noise measurement device automatically switches from the measurement mode to the calibration mode. Note that the calibration mode can be set by providing a mode change switch in the noise measuring device main body 2 and switching the mode change switch from the measurement mode to the calibration mode in advance during the calibration operation.

  Next, in step SP5, the identification unit 10 identifies the microphone M1 on which the acoustic calibrator 3 is mounted. In step SP6, the calibration means 12 calibrates the microphone M1 based on the calibration sound. When calibration for the microphone M1 is completed, the calibration sensitivity obtained by the calibration means 12 is stored in the memory 6 in association with the microphone M1 in step SP7. If the obtained sensitivity is significantly different from the previous time, there is a possibility that some kind of problem has occurred. Therefore, to cancel the calibration and call attention without storing the obtained sensitivity in the memory 6. Issue a warning. The next noise measurement is performed using the newly calibrated sensitivity.

Further, in step SP8, it is determined whether or not calibration has been completed for all the microphones M1, M2,..., MN, and if not completed, the process returns to step SP1 to replace the acoustic calibrator 3 with the next microphone M2. Then, similarly to the case of the microphone M1, the processing of step SP2 to step SP7 is performed to calibrate the microphone M2. By performing such a calibration operation for all the microphones M1, M2,..., MN, the calibration operation is completed.

Next, when performing measurement work, as shown in FIG. 3, in step SP11, the microphone array 1 captures environmental sound. In step SP12, the A / D converter 4 converts the output signal of the microphone array 1 into a digital signal. In step SP13, the identification unit 10 determines that all of the acoustic signals digitized by the A / D converter 4 are environmental sounds.

When the identification unit 10 determines that all of the acoustic signals are environmental sounds, the noise measurement device automatically switches from the calibration mode to the measurement mode. There is also a method of automatically ending the calibration mode at a fixed time after starting calibration without determining the environmental sound. Further, the noise measuring device main body 2 may be provided with a mode change switch, and the measurement mode may be set by switching the mode change switch from the calibration mode to the measurement mode in advance during measurement work. After switching to the measurement mode, the acoustic signal digitized by the A / D converter 4 passes through the identification means 10.

  Next, in step SP14, the identification means 10 identifies the microphones M1, M2,..., MN, and refers to the sensitivity to each microphone microphone M1, M2,. Noise measurement is performed by the noise measuring means 11.

  By simply changing the acoustic calibrator to each microphone that makes up the microphone array, calibration for that microphone is automatically started, so calibration work is simplified, so the use of the noise measurement device according to the present invention is expected to expand. The

Block diagram of a noise measuring device according to the present invention Flow chart showing the operation (calibration work) of the noise measurement device Flow chart showing the operation (measurement work) of the noise measurement device

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Microphone array, 2 ... Noise measurement apparatus main body, 3 ... Sound calibrator, 4 ... A / D converter, 5 ... Signal processing part, 6 ... Memory, 10 ... Identification means, 11 ... Noise measurement means, 12 ... Calibration Means, M1, M2, ..., MN ... microphones.

Claims (1)

In the noise measuring device for measuring the noise using a microphone array, and identifying means for the acoustic signal to identify whether the or environmental sound is a calibration sound from the microphones of the microphone array, an acoustic signal by the identification means Calibration means for automatically calibrating a microphone identified as a calibration sound is provided , and the identification means determines that the sound is a calibration sound when an acoustic signal having a constant sound pressure is input for a predetermined time or more, and the identification means If the acoustic signal from any of the microphones in the microphone array is determined to be a calibration sound, the noise measurement device automatically switches from the measurement mode to the calibration mode .