by Frank Musiek, Ph.D., University of Arizona
In pondering about an article for Pathways I began to think about frequency and duration patterns referred to from now on in this article as FP and DP. The FP test was originally conceptualized by Marilyn Pinheiro and Paul Ptacek at Case Western Reserve University in the early 1970’s. I had the opportunity to work with both of these researchers and eventualy inherited the FP test from Dr. Pinheiro. Later, following Marilyn’s lead, I performed some large validation studies on the FP test (Musiek and Pinheiro, 1987).
Origin of Frequency Patterns
Though there were many motivations for designing a procedure such as the FP, I like to think one of the key factors was the Neff, Butler and Diamond study reviewed beautifully by Neff (1961). Their investigation was on the effect of auditory cortex ablation on hearing (processing) in cats. Though there was little effect on the animals’ intensity or frequency discrimination, there was a marked effect on recognizing patterns of sound. I believe (as best I can remember of discussions with Dr. Pinheiro) this finding was one of the key reasons for developing the FP test. Of course there were other reasons, such as developing a non-speech test and a test of temporal ordering, but I believe it was the early work of Neff, Butler and Diamond that was of considerable influence in the development of the FP. This study by Neff and colleagues is a classic one and all students of audiology should read it. I believe this early central auditory research was the impetus for clinicians and researchers to start thinking about brain effects on hearing. This study also impacted diagnostic audiology in an enduring manner.
What is in a name?
Over the years people have become confused about using the name pitch pattern vs. frequency pattern test — THEY ARE THE SAME TEST! The preferred name should be frequency patterns though I myself sometimes refer to it as pitch patterns! Another name sometimes used is the frequency or pitch pattern sequence test. It should be noted that there are other versions of the FP test out there, but the one that has the norms is the one anchored to the 1987 article —audiologists please note!
Reversals of patterns
In the early studies, Pinheiro and Ptacek (1971) noted that normal subjects would reverse a small number of patterns (HLH for LHL). Because of this Pinheiro felt that these reversed patterns should not be counted wrong since normal performed in this manner. This seemed to be a reasonable decision until around 1980 when I tested some individuals with confirmed neurologically based central auditory disorders. In one case in particular, the patient reversed an extremely high percentage of patterns and were correct on essentially all the rest of the test items. If we counted the reversals correct this individual would have a normal result and would have been misdiagnosed. Marilyn and I convened, discussed the issue and agreed that from that point on, reversals would be counted as incorrect. Despite noting this at national meetings and in publications some still raise the issue about how to treat reversals on the FP test.
As one would expect, musicians perform better on FPs (Defosse and Pinheiro, 1978). That is why it is key to always ask about musical training in taking a patient or research participant history. I would argue that more studies on musicians and pattern perception should be performed. We still do not have a full understanding of music training on FP perception and further well-grounded research is needed.
A Theory: When does the brain code a pattern?
In our 1987 study on patients with confirmed lesions of the auditory cortex performance was poor, but performance from patients with brainstem involvement was fairly good (Musiek and Pinheiro, 1987). Why did this happen? Well I would like to put forth a theory that may explain these findings. At the brainstem level the three acoustic elements are likely processed as three successive individual tones. Therefore at this lower level the patterns are not a pattern but three pure tones. It is well known that pure tones are high redundancy stimuli and therefore the brainstem, though compromised, can process these stimuli quite easily (similar to pure tone thresholds). However, probably somewhere in the sub cortex and or cortex the triplet of tones is no longer perceived as three successive tones but rather a pattern. The accurate processing of a pattern requires much more complex interaction among auditory and non-auditory parts of the brain than three tones. This may be why FPs are sensitive to cortical involvement, but not brainstem compromise. Pattern recognition requires the establishment and preservation of relationships among tones on both a temporal and frequency domains. This kind of processing is likely to take place in higher auditory and cognitive brain centers (see Pinheiro and Musiek, 1985). The brainstem job is simply to maintain the acoustic representation of three tones and forward it to the cortex.
It was logical to follow up the frequency pattern test with duration patterns. Duration discrimination as well as sequencing of three stimuli made this test practically a pure temporal processing procedure. This design, therefore, did not permit the use of a frequency cue to identify the pattern—this later on proved to be a key difference between FP and DP (see Musiek, Baran, Pinheiro, 1990). This procedure was also influenced by Neff, Butler and Diamond, in that although their cats could do frequency and intensity discrimination after ablations, they had trouble with duration just noticeable differences (jnds). This was thought to be a good reason to devise a pattern test with duration as the variable.
Humes, Coughlin and Talley (1996) showed excellent test retest reliability for both the FP and DP. This data was collected on elderly subjects.
A binaural deficit
Interestingly, in many cases but not all of unilateral brain involvement bilateral deficits are noted. The rationale for this is that both hemispheres are involved in decoding patterns (Musiek et al. 1990). Therefore if either hemisphere is involved (or the corpus callosum) bilateral deficits ensue (Musiek et al. 1987; Musiek et al. 1990). However, as alluded to this may not always be the case and we are not sure why.
Both the FP and DP tests are over 25 years old. With the availability of computer control and software programs these tests should be updated. It may be possible to invoke an adaptive procedure in the administration of these tests. This latter maneuver could possibly reduce test time. Further research on the effects of acoustic element duration and duration of the inter-stimulus interval needs to be done on a basic and clinical level. These kinds of modernization of FP and DP tests could make them better procedures and increase utilization. In other words two good tests could be made better with the contemporary software and instrumentation.
DeFosse Pinheiro M. (1978). Perception of Dichotic Pitch Patterns by Musicians and Non-Musicians. Presented at the annual meeting of the American Speech and Hearing Association, San Francisco, CA, November, 1992.
Humes, L. E., Coughlin, M., & Talley, L. (1996). Evaluation of the use of a new compact disc for auditory perceptual assessment in the elderly. Journal of the American Academy of Audiology
Musiek, F., Baran, J. & Pinheiro, M. (1990). Duration Pattern Recognition in Normal Subjects and Patients with Cerebral and Cochlear Lesions. Audiology, 29, 304-313.
Musiek, F.E. & Pinheiro, M.L. (1987). Frequency Patterns in Cochlear, Brainstem, and Cerebral Lesions. Audiology, 26, 79-88.
Neff W. (1961) Neural mechanisms of auditory discrimination. In: Rosenblith W, ed. Sensory Communication. Cambridge, MA: MIT Press, 259-277.
Pinheiro, M.L. & Musiek, F.E. (1985). Sequencing and Temporal Ordering in the Auditory System. In M.L. Pinheiro and F.E. Musiek (Eds.), Assessment of Central Auditory Dysfunction: Foundations and Clinical Correlates, (pp. 219-239). Baltimore, MD: Williams and Wilkins.
Pinheiro M, Ptacek P. (1971). Reversals in the perception of noise and tone patterns. J Acoust Soc Am 49:1778