scope:

This standard defines various types of HADS and describes procedures for measuring their performance characteristics. These procedures are useful for comparing the performance characteristics among various HADS. This standard addresses the measurement of the output characteristics of HADS regardless of the method of transmission. Whenever the device/system is capable of transmitting signals using two or more transmission methods, this standard requires that the output of the device/system be measured using each transmission method.

For the purpose of providing consistent product descriptions and maintaining consistent expectations for product performance for each model, this standard provides:

• guidelines for the description of the physical characteristics of HADS;
• guidelines for the description of the transmission methods used in HADS; and
• procedures for measuring electroacoustic characteristics accurately and consistently.

The electroacoustic characteristics described within this standard are measured at settings described by the manufacturer. These characteristics include:

• family of response curves (50- to 90-dB SPL input in 10 dB increments)
• output sound pressure level for 90-dB SPL input
• high frequency average output sound pressure level for 90-dB SPL (HFA-OSPL90) input
• high frequency average output sound pressure level for 50-dB SPL (HFA-OSPL50) input
• frequency range
• total harmonic distortion
• noise level with no input
• input-output characteristics
• dynamic automatic gain control (AGC) characteristics
• gain control linearity
• current drain
• immunity to EMI (refer to ANSI C63.19 and IEC 60118-13)

This standard describes measurements of output characteristics when a remote microphone arrangement is used. There are potentially multiple components to HADS (e.g., FM transmitter delivering to an FM receiver connected to a neckloop transmitting to a t-coil in a hearing aid), and several employ output transducers that cannot be measured with standard couplers.

This standard does not address measurement of hearing aids or personal sound amplifiers which can be evaluated according to procedures described in ANSI/ASA S3.22. This standard also does not describe measurements of large-area assistive listening systems that are not packaged for individual coupling to the listener's ear, telephone amplifiers, and alerting devices. The document addresses devices not worn entirely on the body. The standard also excludes measurement of implants and bone conduction devices. These devices require substantially different techniques from those described in this standard because they do not deliver signals via air conduction to the individual's ear. Some hearing aids may contain conventional amplification and wireless receivers. Conventional amplification via the local microphone should be tested by ANSI/ASA S3.22, and the wireless functionality should be tested according to this standard. Further descriptions of HADS appear in Clause 3. It is not the intent of this standard to restrict the variety of HADS available nor to inhibit in any way advances in the state of the art. In addition, it is not the intent of this standard to provide measurement procedures that can be used to predict in-situ performance.