Test of Basic Auditory Capabilities,
Modification 4 (TBAC-4)

And the National Auditory Capabilities Database (NACD)

What prompted the development of the TBAC test battery?

In the 1970s auditory research began to turn from studies of such simple stimuli as single tones, noise bursts, and clicks, to much more complex sounds, including spectral and temporal patterns comprised of multiple tones (Watson and Kidd, 19xx). It had previously been established that the range of masked thresholds, for young adults with clinically defined normal hearing, for single tones presented in a noise background was rarely more than 2-3 dB, and the ranges for the discrimination of single tones on the basis of changes in frequency, intensity or duration was similarly quite small. Thus it was somewhat surprising to learn that the range of thresholds for tones presented within complex auditory patterns was often found to be as great as 20-30 dB (Green, Profile Analysis, 1988), and the range for the detection of changes in spectral or temporal properties of complex sounds was similarly large (Watson and Kelly, 1981). Some listeners seemed much more able than others to focus their attention on spectral or temporal details of complex sounds. This prompted a return to studies of individual differences in performance on various auditory tests (Johnson, Watson and Jensen, 1987), which had been largely neglected during the last quarter of the 20th century. The TBAC test battery was developed with the goal of establishing norms for auditory abilities beyond that of the sensitivity to pure tones. To help understand this goal, consider that vision might be tested by determining how bright a red, blue or green spot of light must be for a person to barely detect its presence. It does not seem surprising that this analog to determining the intensity required for a pure tone to be detected is NOT the standard method of testing the functioning of the visual system. Instead a person¡¯s vision is tested by asking how large letters must be on a screen before they can be correctly identified, or whether they can distinguish a short line segment from a longer one. These latter are acuity measures, and auditory acuity is a property that varies among people considered to have clinically normal hearing, just as visual acuity (and sensitivity) vary among some persons with clinically defined normal vision. When the distributions of auditory sensitivity in the population were first documented in the late 19th and early 20th century, persons who could not detect sine waves until they were raised 15-20 dB above the levels required by most young adults were defined as having abnormal sensitivity, or hearing loss. Later, the amount of sensitivity loss that was considered clinically significant, at many different frequencies across the audible spectrum, was decided by national and international committees (ISO ref.). No such definitions of abnormal auditory acuity have been established, since there have been neither generally accepted tests of acuity nor the large-scale databases needed to determine the range of performance for most young adult listeners without known auditory pathology.

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