ANSI CTA 2051-2017 pdf free download – Personal Sound Amplification Performance Criteria.
4 Criteria for Standardization
Three categories of standardization level are defined and described below. These categories identify three levels of technical performance specification differentiated by a decrease in the degree of standardized specification required for fulfilment of the feature requirements. The level of performance specification recommended by this document for each feature is independently identified for each feature within the associated sub-section. Measurement methods for evaluation of all relevant metrics characterized in the feature specific sub-sections are identified and described when appropriate. Category 1 : The description of a hearing device performance parameter which must include the value measured per the specified testing method. Category 1 requirements include a threshold or acceptable range for the parameter measured.
Category 2:The description of a hearing device performance parameter which must include the valuemeasured per the specified testing method.Category 2 requirements do not include a threshold oracceptable range for the parameter measured.
Category 3: Presence of the technological capability or feature shall be reported in the device description.The specific value/metric for measurement of this value is not within the scope of the standard.
Measurements in this standard specify the use of tones (sine waves) as a stimulus signal. lt isrecognized that many devices will include non-linear audio processing (DSP) (for example, noisesuppression, band equalization) that may cause unexpected test results when tones are used as teststimulus signals. Therefore , when performing measurements using tones as specified in Section 4.1,4.2,4.3,4.4,4.5,4.6,and 4.7,any non-linear signal processing should be disabled.
Alternatively, if using tones is not appropriate for testing a specific device, for example, due to the inabilityto disable non-linear processing, alternative test signals such as real speech and 1i/3 octave pulsednoise signals may be used. lf an alternate test signal is used, 1/3 octave analysis should be pertormedto obtain individual frequency based test results, similar to what would have been obtained if tone-basedmeasurements were performed.
As in ANSI S3.22-2014,Section 5.2.5, controls of the device under test shall be set for the widestavailable frequency response range, e.g., tone control typically set for minimum effect.
As in ANSI S3.22-2014,Section 4.1 , test signal(s) shall exceed background noise by at least 10 dB, andunwanted stimuli shall be sufficiently low so as not to affect the test results by more than 1 dB.
ln addition to the tests included in this standard, it is recommended that informal listening tests be
performed during both product development and final evaluation to ensure that there are no undesirableeffects present that are not revealed by objective testing.
Categorv 1
4.1 Frequency Response Bandwidth (Category 1)
Frequency Response Bandwidth of a sound reproduction system relates to the portion of the inputacoustic spectrum that the device can provide to a user. A consistent methodology for measurement(relative to a common reference) and assessment of the spectrum width provides the consumer a meansto compare and evaluate competing systems.
The upper and lower cut off frequencies are defined as the frequencies at which the estimated insertionresponse falls 10 dB relative to the average level of the insertion gain in the one-third octave bands from500 to 3150 Hz.
The low frequency cut off for all devices shall extend to 250 Hz or below.
Devices labeled as “Standard Band” shall have an upper cut off frequency of 5 kHz or greater.
Devices labeled as Wide Band shall have an upper cut off frequency of 10 kHz or greater.
Frequency response bandwidth shall be reported and labeled on the packaging.
Method: Frequency response is measured in a coupler according to ANSI S3.22-2014 using an 80 dBSPL input signal. The one-third-octave insertion gain response shall be calculated from the values of thepressure response measured in a 2cc coupler or an occluded ear-simulator coupler (as specified in IEC60318-4,commonly called a “711” coupler).ANSI CTA 2051 pdf download.