Marilyn L. Pinheiro

Duration Pattern Recognition in Normal Subjects and Patients with Cerebral and Cochlear Lesions

Three groups of subjects were tested on a duration pattern recognition task. The groups included normal subjects, subjects with cochlear hearing loss, and subjects with lesions involving but not limited to the auditory areas of the cerebrum. Results indicated no significant difference in pattern recognition between the normal subjects and subjects with cochlear hearing loss. However, the subjects with cerebral lesions performed significantly more poorly than either the normal subjects or those with cochlear hearing loss. In comparing pattern recognition performance for the ears ipsilateral and contralateral to the lesioned hemispheres no differences were noted. Rather, when a central lesion was present, both ears generally yielded abnormal scores.

Frequency patterns in cochlear, brainstem, and cerebral lesions

Three groups of patients with different pathologies (cerebral, brainstem, and cochlear lesions) were tested and compared for performance on frequency patterns. Results indicated that the frequency pattern test was highly sensitive to cerebral lesions (83%), but not as sensitive to brainstem lesions (45%). There was very little overlap between results of subjects with cochlear hearing loss and those with cerebral lesions. The specificity of frequency patterns for detecting cerebral lesions (the number of true negative results divided by the number of cochlear subjects) was 88.2%.

Reversals in the Perception of Noise and Tone Patterns

Perception of auditory patterns based on an intensity difference was investigated in 20 experienced normal‐hearing subjects under binaural and monaural listening conditions. Patterns were made up of either three white‐noise bursts or three 1000‐Hz tone bursts which were temporally spaced. Bursts within each pattern differed only in intensity and were either loud (L) or soft (S), i.e., each pattern included one of one intensity and two of the other. The six possible patterns were SLS, LSL, LLS, SSL, LSS, and SLL. The loud bursts remained at a constant intensity and the soft bursts were attenuated by either 9, 7, 5, or 3 dB. Patterns were presented at 50 dB sensation level. Tone‐burst patterns were easier to perceive and resulted in a larger number of correct responses than noise‐burst patterns. However, there was no significant difference between tone‐burst patterns and noise‐burst patterns in the percentage of errors that were pattern reversals. Symmetrical patterns were reversed more frequently than asym...

Pattern Reversal in Auditory Perception

Perception of auditory patterns based on an intensity difference was tested in 30 normal subjects under binaural, monaural, and dichotic listening conditions. Each auditory pattern was made up of three temporally spaced white‐noise bursts involving two elements, i.e., “Soft” (S) and “Loud” (L). Patterns included SLS, LSL, LLS, SSL, LSS, and SLL. The loud element in the patterns remained at a constant intensity throughout, with the soft elements attenuated from 5 to 20 dB in different sets of patterns. Patterns were presented at 50 dB SL. Subjects needed a 10‐dB intensity difference within a pattern in order to recognize it correctly half the time, although the just noticeable difference (jnd) for white noise is about 0.5 dB. This seems to indicate that the pattern recognition task is a higher auditory function than simple discrimination of intensity differences. An unexpected finding was a large number of complete pattern reversals or mirror images which accounted for 30%–40% of errors across listening co...

Interaural Intensity Difference for Intracranial Lateralization

The interaural intensity difference (IID) for intracranial lateralization of white‐noise bursts was investigated in 17 normal subjects, in 17 subjects with high‐frequency sensorineural hearing losses, and in 17 subjects with predominantly unilateral cerebral lesions. Broad‐band‐ and low‐pass filtered‐noise bursts with durations of 76 msec and 506 msec and a fast rise time of 10 msec were used for the dichotic signals. These were presented relative to the hearing sensitivity in each ear. There were no statistically significant differences between normal and sensorineural subjects except for the filtered noise condition, which resulted in a slightly but significantly greater IID for subjects with hearing losses. In subjects with cerebral lesions, the IID for the ear contralateral to the lesion was much smaller than the IID for normal or sensorineural ears, while the IID for lateralization to the ear ipsilateral to the lesion was slightly larger than the normal IID. It was found that the model for neural int...

Effect of peripheral and central auditory lesions on auditory pattern perception

Auditory patterns composed of three successive tone bursts of either 880(Low) or 1122(High) Hz were arranged to yield six types of patterns (i.e., LLH, LHL, HLL, HHL, HLH, LHH). The tones in the patterns had a 150‐ms duration, 10‐ms rise‐fall and 200 ms interstimulus interval. A normal performance criteria for these monaurally presented patterns was established on 31 normal subjects. Pattern data were then collected on groups of subjects with documented lesions of the cochlea, brain stem, or auditory areas of the cerebrum. Results indicated that almost 90% of subjects with cochlear lesions (N = 29) performed within the normal criteria, while over 80% of the 29 subjects with cerebral lesions yielded abnormal results. Approximately one half of the 22 subjects with brain stem involvement demonstrated normal performance on the pattern task. An additional analysis revealed that a high percentage of subjects with lesions limited to one hemisphere demonstrated bilateral ear deficits for pattern identification.

Processing of temporal patterns by split brain patients

Three normal‐hearing right‐handed patients, who underwent complete section of the corpus callosum because of medically uncontrollable seizures, were tested on auditory tone patterns. The pattern stimuli were composed of three 1000‐Hz tone bursts with two different intensities (ΔI = 7 dB) or three tone bursts of two different frequencies (high = 1222 Hz, low = 880 Hz). The duration of the intensity patterns was 250 ms while the duration of the frequency patterns was 150 ms. Interstimulus interval was 200 ms for all patterns. A total of 30 intensity and 30 frequency patterns were presented through earphones at a 40‐dB sensation level to each ear of the subjects. Only one of the patients was tested preoperatively while all three were tested postoperatively. The one patient preoperatively performed at a near normal level for pattern perception whereas the three patients tested postoperatively performed at a level of chance or slightly better on both auditory pattern tests. Based on these results, it is hypoth...