1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA LC 1-2007 (R2013)Test Procedure for Compatibility Of Hearing Aids and Ultrasonic Lighting Control DevicesNEMA LC 1-2007 (R2013) Test Procedure for Compatibility Of Hearing Aids and Ultrasonic Lighting Control Devices Publish
2、ed by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 www.nema.org Approved October 10, 2013 Published November 20, 2013 2013 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the U
3、niversal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. LC 1-2007 (R2013) Page ii 2013 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication
4、was considered technically sound by a consensus among persons engaged in its development at the time it was approved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA
5、) standards and guideline publications, of which the document herein is one, are developed through a voluntary standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. Although NEMA adm
6、inisters the process and establishes rules to promote fairness in the development of consensus, it does not write the documents, nor does it independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guidel
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13、the statement. LC 1-2007 (R2013) Page iii 2013 National Electrical Manufacturers Association TABLE OF CONTENTS Foreword . ii Section 1 GENERAL . 1 1.1 Scope . 1 1.2 References 1 1.3 Test Equipment . 1 1.4 Reference Ultrasonic Transducers 1 1.4.1 Frequency . 1 Section 2 TERMINOLOGY RELATED TO DETERMI
14、NING THE MAXIMUM SIGNAL LEVEL IN THE TEST SET-UP . 2 2.1 Minimum Distance . 2 2.2 Ultrasonic Transducers Output . 2 2.3 Test Distance . 2 2.4 Maximum Voltage 2 2.5 Maximum Sound Pressure Level. 2 Section 3 TEST SET-UP AND PROCEDURES 3 3.1 General 3 3.2 Initial Test Set-Up 3 3.3 Hearing Aid Noise Tes
15、t Procedure 4 Tables 1-1 Example Reference Data for Ultrasonic Transducers . 1 2-1 Maximum Sound Pressure Levels when 30 in. from a Standard Ultrasonic Occupancy Sensor . 3 LC 1-2007 (R2013) Page iv 2013 National Electrical Manufacturers Association Foreword This publication has been developed to ad
16、dress the potential for interference between hearing aids and ultrasonic lighting control devices (occupancy sensors). Some occupancy sensors may occasionally interfere with normal acoustic signal processing in some digital hearing instruments causing significant noise and distortion of the signal.
17、This publication provides a basis to evaluate the possible interactions between ultrasonic lighting control devices and hearing aids utilizing a set of test procedures. This evaluation can be used as the basis for specifying performance criteria for both hearing aids and occupancy sensors to elimina
18、te interference complaints. The Lighting Controls Section of NEMA reviews this test procedure periodically for any revisions necessary to keep up to date with the latest technological advances. Proposed revisions or comments should be submitted to: Senior Technical Director, Operations National Elec
19、trical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 Members of the NEMA Lighting Controls Section developed this Standards Publication. Section approval of this standard does not necessarily imply that all section members voted for its approval or participated in its
20、 development. At the time it was approved, the Lighting Controls Section was composed of the following members: Acuity Brands Lighting Eatons Cooper Lighting GE Lighting Hubbell Building Automation Leviton Lighting & Energy Solutions Lutron Electronics Company, Inc. OSRAM SYLVANIA Philips Lighting E
21、lectronics North America RAB Lighting Schneider Electric Universal Lighting Technologies WattStoppper LC 1-2007 (R2013) Page 1 2013 National Electrical Manufacturers Association Section 1 General 1.1 SCOPE This Standards Publication sets forth test procedures for use with a small acoustic chamber to
22、 evaluate potential interactions between hearing aids and ultrasonic lighting control devices, hereinafter referred to as occupancy sensors. The test procedures are designed to simulate and test occupancy sensors at three typical, specific frequencies (25 kHz, 32.7 kHz, and 40 kHz) and one type of h
23、earing aid. However, if there are multiple hearing aids, the test procedures are repeated as many times as necessary. 1.2 REFERENCES This document is based on the report of David F. Henry and Barak Dar, Effects of Ultrasonic Occupancy Sensors on Hearing Aids, dated February 22, 2006. 1.3 TEST EQUIPM
24、ENT Test equipment to be used includes: 2CC acoustic coupler Acoustic test chamber Milli-voltmeter, or oscilloscope Ultrasonic occupancy sensor transducers Voltmeter Wave function generator 1.4 REFERENCE ULTRASONIC TRANSDUCERS Three sets of ultrasonic transducers (transmitter and receiver) are used
25、to perform the compatibility testing. Each transducer set is tuned to one of the common ultrasonic occupancy sensors operating frequencies, i.e. 25, 32.768, or 40 kHz. The transmitter is calibrated to produce a known sound pressure level at the 12 in. (30 cm) specification distance and the receiver
26、is calibrated to produce known electric output signal levels with specified input levels. An example of transducer data is shown in Table 1-1. Table 1-1 Example Reference Data for Ultrasonic Transducers ID Frequency Transmitter Specification Voltage (VSPEC) Specification Distance DSPEC (in. cm) Soun
27、d Level Meter - SPLSPEC (dB) Receiver RSPEC (VP-P square wave) 25 25 kHz 20 VP-P square wave 12 in. (30 cm) 111 976 32 32.768 kHz 115 1200 40 40 kHz 117 1170 LC 1-2007 (R2013) Page 2 2013 National Electrical Manufacturers Association Section 2 TERMINOLOGY RELATED TO DETERMINING THE MAXIMUM SIGNAL LE
28、VEL IN THE TEST SET-UP 2.1 MINIMUM DISTANCE The minimum distance DMIN that a hearing aid will be from an ultrasonic occupancy sensor is assumed to be 30 in. (76 cm). 2.2 ULTRASONIC TRANSDUCERS OUTPUT For specification purposes, the measurement of the ultrasonic transducers outputs are made at a dist
29、ance (DSPEC) of 12 in. (30 cm) by applying 10 Vrms square wave (VSPEC) to the transmitter. 2.3 TEST DISTANCE The test distance DTEST is the distance between the ultrasonic transmitter and the hearing aid under test. 2.4 MAXIMUM VOLTAGE The voltage resulting in the maximum sound pressure level (SPL)
30、from the ultrasonic transmitter at the test distance is VMAX = VSPEC/(DMIN/DTEST). 2.5 MAXIMUM SOUND PRESSURE LEVEL The SPL that should be measured at DMIN, or 30 inches (SPLMAX), is determined using the following formula: SPLMAX = SPLSPEC 20 x log (DMIN/DSPEC) Given DMIN = 30 in. and DSPEC = 12 in.
31、, SPLMAX should equal SPLSPEC 8 db. LC 1-2007 (R2013) Page 3 2013 National Electrical Manufacturers Association Section 3 TEST SET-UP AND PROCEDURES 3.1 GENERAL The following test procedure is designed for a small acoustic test chamber designed to test hearing aids and is commonly available at a hea
32、ring aid manufacturing facility that can accommodate only a 6 in. distance between transducer and hearing aid. To simulate the maximum probable SPL that is expected to occur at 30 in. in the real world at 6 in. in a test box, the test signal VMAX should be 2 VP-P. 3.2 INITIAL TEST SET-UP 3.2.1 Conne
33、ct the ultrasonic occupancy sensor transmitter to a function generator (FG) and voltmeter. See Figure 3-1 for set-up. Set the function generator to the nominal transducer frequency, square wave, and 4 Vp-p. Measure the voltage on the milli-voltmeter connected to the ultrasonic occupancy sensor recei
34、ver. FG V V6 in .V MAXU l tr as on i cT r an s m i tte rU l tr as on i cR ec ei v erFigure 3-1 Schematic of Test Set-up 3.2.2 If a sound level meter for ultrasonic frequencies is not available, use the output voltage level of the reference ultrasonic receivers to determine the sound pressure level b
35、y verifying that sound pressure levels (SPL) from the transmitter are close to the specification values less 8 dB. See the example in Table 3-1 below. Table 3-1 Maximum Sound Pressure Levels when 30 in. from a Standard Ultrasonic Occupancy Sensor Expected Levels from 6 in. (15 cm) with 4 Vp-p Square
36、-wave to Transmitter ID Frequency Receiver SPL (dB) Company A 25 kHz 390 mVp-p 103 Company C 32.7 kHz 480 mVp-p 107 Company F 40 kHz 466 mVp-p 109 3.2.3 Connect the receiver to a milli-voltmeter (or oscilloscope). LC 1-2007 (R2013) Page 4 2013 National Electrical Manufacturers Association 3.2.4 Plac
37、e the transmitter and receiver transducers 6 in. (15 cm) apart in an acoustic test chamber. 3.2.5 Apply 2 Vp-p square wave at nominal frequency to the transmitter and verify that the output level from the receiver is the specification value (Rspec) less 8 dB (/2.5) as per example in Table 1-1. 3.3 H
38、EARING AID NOISE TEST PROCEDURE 3.3.1 Replace the receiver with a hearing aid and 2CC/real-ear coupler. Make sure the coupler does not obstruct a “line of sight” between the hearing aid microphone and the transmitter. 3.3.2 Reducing the signal level will simulate a greater distance from the ultrason
39、ic occupancy sensor. For example, reducing the signal level to 1 Vp-p will simulate a distance of 1.5 m (5 feet) from a standard ultrasonic occupancy sensor producing the maximum possible acoustic output. 3.3.3 Output of the hearing aid should be recorded with and without US signal, and the hearing
40、aid should be more informally tested by moving it through an arc of 180 in front of the transducer, both vertically and horizontally, while monitoring its output. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB
