The digital hearing aid has key features as summarized in Table

Amplification characteristics are arguably the most important features that will determine the usefulness of a hearing aid. Therefore, an approach to systematically and universally test and benchmark these devices via standardized tests are needed. Rechargeable hearing aids supplier.  Indeed, at present testing electroacoustics performance of hearing aids generally can be done to serve two purposes: (1) to verify that the instrument is functioning properly—according to the manufacturer’s specifications and (2) to verify that the instrument is functioning appropriately—according to auditory needs of the wearer. In the first case, because the hearing aids are to be used by humans, the devices need to be objectively proven that they are safe to wear, and as much as possible they need to provide relevant functions such as amplification gains that will be useful for hearing impaired. Testing in the second case, on the other hand, is done after the device is fitted to the wearer, with real-ear measurement performed to confirm that the electroacoustic characteristics during actual usage are as intended, for example, whether the gain measured in the real ear is equal to the intended gain calculated.

For device development purposes, the measurement issues concerned here are with regard to the first purpose. Within the scope, the International Electrotechnical Commission (IEC) and American National Standards Institute (ANSI) are arguably the two world-leading organizations for standardization of electroacoustic measurements in hearing aids. The most important sets of standards are the IEC-118 (IEC 60118) and ANSI-322 (ANSI S3.22) which cover most of the tests required. They are similar to a certain degree, and usually, a hearing device certified for compliance with at least one of the standards should be sufficient.

Among these standards, IEC 60118-0 measurement of electroacoustic characteristics and IEC 60118-7 measurement of the performance characteristics of hearing aids for quality inspection for delivery purposes are the two most relevant measurements for consumer protection. As the name suggests, IEC 60118-0 provides basic details about measurement characteristics and set up schemes that are involved in hearing aid measurement. The standard defines the measurement of physical performance characteristics of air conduction hearing aids based on a free-field technique and measured with an ear simulator. It describes methods of measurement for evaluating electroacoustic characteristics of hearing aids. IEC 60118-7 is closely related to t 60118-0, but this part of IEC 60118 gives recommendations specifically for the measurement of the performance characteristics of air-conduction hearing aids of a particular model for production, supply, and delivery quality assurance purposes. The manufacturer will normally assign such nominal values upon delivery, and the buyer can test and check its performance whether it conforms to the manufacturer’s claim. The standard provides information on how the hearing aids should be set up and what measurements are to be made. It is not intended to be used as a predictor for real-ear performance. IEC 60118-7 requires that the hearing aid needs to be measured in a sound-proof environment (usually in an anechoic box). The device is connected to a 2cc coupler that simulates simple ear volume. The hearing aid receives a reference signal via a calibrated speaker and outputs an amplified sound that is detected by the measurement microphone via the coupler. The result obtained is processed to provide corresponding electroacoustic data of the device. All necessary test parameters such as exact placements and angles between the devices and signal strength or characteristics are all specified in the standard.

Our research team has set up our own electroacoustic testing facility that can support electroacoustic measurements according to the requirements set by the standards called the HA-TEST (Figure 3). It consists mainly of an anechoic box with 2cc coupler, computer with the special sound card running professional sound measurement software, power amplifier, and a current supply/measurement device. To make sure about the accuracy of our test results, we compared the initial test results of a sample device with ones obtained by having the same device tested by a certified laboratory abroad. The PDN-01B had gone through the electroacoustic tests following the IEC 60118-7 standard, with the measurement results as shown in Table 3. It can be seen that the fitting rage of the PDN-01B hearing aid suits those with moderate-to-severe impairment as intended.