i3 | December 12, 2017

Over-the-Counter Hearing Aids and CTA's New Standard

Steve Smith
A woman's face, focused on her left ear

President Trump recently signed into law a requirement that hearing aids be made available over-the-counter.

Bringing over-the-counter hearing aids to consumers is a top priority for CTA, and the successful navigation of the legislative process was an important element in CTA’s effort. The other element was the creation of a voluntary industry standard describing minimum performance criteria for these devices. That standard was published this year along with a new logo to help consumers identify products that comply with it.

ANSI/CTA-2051, Personal Sound Amplification Performance Criteria, covers a range of operating parameters for devices that assist with hearing but have not gone through the U.S. government approval process to become prescribed hearing aids. ANSI/CTA-2051 addresses a range of operating characteristics including things like frequency response, maximum acoustic output, distortion control, high-frequency gain, latency and battery life, just to name a few.

The CTA standard organizes device operating parameters into three categories. Category 1 parameters must be within a defined range, and must be tested using the methods described in the standard. Category 2 parameters do not have to be within a defined range, but they must be measured and reported using the procedures described in the standard. Category 3 parameters do not have to be within a defined range and do not have to be measured, but the existence of the device capability or feature needs to be reported.

ANSI/CTA-2051 Logo Program

A new logo program was established to help consumers recognize devices that comply with ANSI/CTA-2051. This logo indicates the device was tested using the methods described in ANSI/CTA-2051 and found to comply with all relevant performance requirements in the standard. The standard was developed by CTA’s Portable, Handheld and In-Vehicle Electronics Committee, which is working on a number of other standards related to health, fitness and wellness through its Health, Fitness and Wellness Subcommittee.

Category Parameters

Category 1 parameters include frequency response bandwidth, frequency response smoothness, maximum acoustic output, distortion control limits and self-generated noise levels. All of these parameters must be measured and fall within an acceptable range.

Category 1: CTA Performance Criteria for PSAPs

  • Frequency Response Bandwidth: Standard band: 250 Hz – 5 kHz | Wide band: 250 Hz – 10 kHz
  • Frequency Response Smoothness: No single peak in the 1/3 octave frequency response shall exceed 12 dB relative to the average levels of the 1/3 octave bands 2/3 octave above and below the peak.
  • Maximum Acoustic Output: The maximum output sound pressure level shall not exceed 120 dB SPL measured in a 2cc coupler. Note: This is equivalent to a level of roughly 115 dBA referred to the sound field.
  • Input Distortion: THD+N = 5% or less with 500 Hz tone applied to microphone at 100 dB SPL
  • Output Distortion: THD+N = 5% or less at 70 and 100 dB SPL output with 500 Hz input
  • Self-Generated Noise: No more than 32 dBA (equivalent SPL) referred to the input

Category 2 parameters include high-frequency gain, battery life, latency and RF immunity. These parameters must be measured and reported but do not have to be within a defined range.

Category 3 parameters include tone control, level dependent gain/compression, signal-to-noise ratio enhancement, noise reduction, feedback control/cancellation, device personalization, device coupling to the ear, and wireless connectivity. No measurement methods are defined for these parameters and there are no defined limits for compliance, either. The existence of these features in a device simply needs to be reported.

November/December 2017 i3 Cover Issue

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