Which of the following is NOT a component that must be included in hearing aid manuals?

In the context of hearing aid manuals, it's essential to provide users with comprehensive information about the device's performance and specifications, which helps them understand how to use it effectively. The ANSI SSPL 90 curve, average full-on gain, and frequency response curve are all critical acoustic measurements that illustrate the hearing aid's performance characteristics. These metrics inform users about the hearing aid's amplification capabilities, frequency ranges, and how it performs in varying auditory environments.

On the other hand, while customer service contact information is important for user support, it is not classified as a technical specification of the hearing aid itself. Therefore, it does not fall under the mandatory components such as performance specifications that must be included in hearing aid manuals according to industry standards. This distinction highlights the focus of the standard requirements on the acoustic and technical attributes of the hearing aid rather than the logistical support aspects that customer service information covers.