(PP311) Verification of SmartBug Radio Receivers Using ANSI Standard 3.47

Abstract: The ANSI Standard 3.47 (ANSI S3.47) outlines the electroacoustic measurements to be made with assistive listening devices (ALDs) to allow comparison with units within and across manufacturers. The purpose of this study was to assess the electroacoustic characteristics of Smart Bug radios according to ANSI S3.47, and compare the acoustic consistency across two carrier frequencies. Twenty devices were assessed using the Simulated Head and Pinna coupling system and the Fonix 8000 hearing aid test system. Results are reported as ranges of values to illustrated the variability and support the need for manufacturers to provide product specifications according to ANSI S3.47.

Summary: Rational/Purpose
The ANSI Standard S3.47 outlines the electroacoustic measurements to be made with assistive listening devices (ALDs) to allow comparison with units within and across manufacturers. However, little research exists investigating the electroacoustic properties of assistive listening devices (ALDs). ALDs can be sold over-the-counter or may be provided at a public venue to provide accommodations for persons that are Deaf of Hard-of-Hearing (D/HoH). While these Devices can, in certain situations, be considered a reasonable accommodation at a public venue to help D/HoH listeners acquire access, it is important that these devices be considered safe to use. Additionally, the acoustical quality of these devices is vital to the listener experience. For example, an assisted listening device that has high levels of distortion or under amplification can impact access to obtaining the appropriate targeted message, which overall is counterproductive to access for D/HoH listeners. Additionally, a device that outputs levels that are too intense may be damaging to a person’s auditory system. The purpose of this study is to: 1) Determine the test/retest reliability of the ALDs when using the Simulated Head and Pinna System as a coupling method with the SmartBug headset/receiver; 2)Determine the electroacoustic measures of ten two-channel 216 Hz receivers when connected to Channel A 216-217 transmitters; 3) Determine the electroacoustic measures of the 72 Hz receivers; and 4) Determine the difference in electroacoustic measures for the wireless receiver when connected to a Listening Technologies Wide Area transmitter 216-217 Hz versus a 72-76 Hz transmitter.
Methods
Using ANSI S3.47 guidelines and recommendations, the devices were coupled to a Simulated Head and Pinna system that was coupled to the Fonix 8000 hearing aid test box. Data were collected for a subset of the S3.47 measures and included the OSPL 90, HFA OSPL 90, attack and release times, full on gain, reference test gain, measured reference test gain, the level of noise in the coupler and total harmonic distortion for 500, 800 and 1600 Hz. Descriptive statistics were applied to determine the median and ranges for each measure. Due to no known manufacturer specifications for the Smart Bug radio systems, descriptive results are reported.
Results/Conclusion
Results showed that the coupling method for the SHAP system was reliable within 2dB. The range of values across the receivers were as follows: HFA OSPL 90 (78.7 to 105.1 dB), attack (0 to 37 ms) and release times (91 to 911 ms), full on gain (-1.8 to 35.6 dB), measured reference test gain (1.01 to 27.2 dB), the level of noise in the coupler with no input (49.5 to 82.4 dB), and total harmonic distortion for 500 (0 to 11.9%), 800 a (0 to 6.2%), and 1600 Hz (0 to 4.2%). The effect of the carrier frequency showed that when using the 72-76 Hz carrier frequency, outputs were more intense than when using the 216-217 Hz carrier frequency. In conclusion, manufacturers need specifications for outputs when developing assistive listening devices.