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Results for “PITCH DISCRIMINATION”

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Pitch discrimination of harmonic complex signals: residue pitch or multiple component discriminations?

Two models for pitch discrimination of harmonic complex sounds are discussed, a multiple-band probability summation model using comparisons among component frequencies, and a model in which residue pitches are compared. The second model is based on Goldstein's optimum-processor pitch theory [J. Acoust. Soc. Am. 54, 1496-1516 (1973)], and is distinguished from the multiple-band model by an internal noise process. Pitch difference limens from 2I2AFC tasks show that when the test signals comprise corresponding harmonics, relative pitch difference limens are less than the smaller relative difference limens for the component frequencies, which is consistent with the multiple-band model. The absence of corresponding harmonics significantly reduces relative pitch discriminability; this effect supports the model on Goldstein's theory. It appears that residue pitch comparisons are not used for pitch discrimination between sounds with corresponding components; rather, comparisons based on residue pitch are only employed where there are no common resolved components in the signals to be discriminated.

Acoustic Stimulation↗

Cerebral correlates of hemispheric lateralization during a pitch discrimination task: an ERP study in dichotic situation.

OBJECTIVE: Electrophysiological correlates of perceptual asymmetry for dichotic pitch discrimination were investigated in 12 right-handed volunteers, whose dichotic listening performances attested the classical 'right ear advantage' in a verbal discrimination task. METHODS: Event related potentials (ERPs), elicited by dichotic and binaural pairs of tones applied in a classical oddball paradigm including right ear targets, left ear targets and binaural targets (5% occurrence each) were recorded from medial and lateral scalp locations. Latencies and baseline to peak amplitudes were measured for P1, N1, P2, N2 and P3 components. RESULTS: ERPs recorded in response to dichotic (compared with binaural) target pairs, exhibited delayed latencies for N2 and P3, correlated with prolonged RTs, probably linked to greater difficulty in identification of the target. They also displayed enhanced N1 and P2 voltages, which may reflect the simultaneous activation of two different populations of neurons in the auditory cortical areas. We observed specific lateralization effects for pitch discrimination with a left ear advantage on latency of early components. CONCLUSIONS: Together with amplitude asymmetries in the N2 component, the findings bring strong electrophysiological support to Kimura's structural model for dichotic perceptions with a right hemisphere prevalence in a pitch discrimination task.

Acoustic Stimulation↗

The results in patients implanted with the nucleus double array cochlear implant: pitch discrimination and auditory performance.

OBJECTIVE: In patients with total or surgically inaccessible cochlear obliteration, only a reduced number of active electrodes can be inserted with standard cochlear implants, resulting in below average auditory performance. Therefore, a special implant with two electrode arrays was developed on the basis of the Nucleus 22 cochlear implant, the socalled Double Array. One electrode array with 11 active electrodes is inserted into the basal turn of the cochlea, while the second array with 10 active electrodes is inserted into the second turn. The Double Array is now available on the basis of the more advanced Nucleus 24 with 11 active electrodes on each array and two reference electrodes, one at the case and the second one an additional ball electrode, which is placed under the temporalis muscle. For device description and surgical technique see Lenarz et al. (2001). This paper presents psychophysical data on pitch discrimination and auditory performance of patients implanted with a Double Array on the basis of the Nucleus 22. STUDY DESIGN: A prospective intra-individual study using a Latin square paradigm was performed in six adult patients with obliterated cochlea who received the Nucleus 22 Double Array. After appropriate fitting and loudness balancing, patients were tested either with the basal, the apical or both electrode arrays. Apart from auditory performance tests including numbers and monosyllable word tests, pitch discrimination was determined with a defined procedure. RESULTS: When activating each array alone, auditory performance was better with the basal array than with the apical array. Both arrays together showed marked improvement compared with the basal array, indicating an additional effect of the second array. Pitch discrimination was significantly better for the electrodes in the basal turn than in the second turn, indicating differences in electrical excitation of the auditory nerve fibers. Pitch discrimination was positively correlated with auditory performance data. CONCLUSION: The additional apical array leads to significant improvement in auditory performance in patients with obliterated cochleae by increasing the number of intracochlear electrodes. Despite reduced pitch discrimination, the apical array provides important information for speech recognition. For this reason the Double Array provides a profound advantage for patients with obliterated or surgically inaccessible cochleae.

Acoustic Stimulation↗

The assessment of pitch discrimination ability in young children.

This study tested the hypothesis that some tasks used in assessing pitch discrimination ability may instead by assessing children's ability to deal with relational language. Five tasks were given to 36 normal children who were equally divided into three age groups, six to six and one-half years, seven to seven and one-half years, and eight to eight and one-half years of age. Task 1 involved a training procedure to assess the children's ability to hear the differences in the pitch of two tones, which were an octave apart. A simple motor response was required. Task 2 assessed the children's ability to label these tones as high or low. Task 3 assessed their ability to compare two tones and label the second as higher or lower than the first. Task 4 examined their ability to label as high or low the position of a man on a ladder. Task 5 examined their ability to compare the positions of two men on two ladders and say whether the second man was higher or lower than the first. Results indicated that children who make pitch discriminations as demonstrated by nearly perfect scores on Task 1 often fail to demonstrate those discriminations on tasks requiring relational language. A comparison of Tasks 2 and 3 to Tasks 4 and 5 suggests that children in the age range studied are less proficient in applying high-low and higher-lower to pitch than to spatial relations.

Child↗

Harmonic partials facilitate pitch discrimination in humans: electrophysiological and behavioral evidence.

The effect of the spectral tone structure on pre-attentive and attentive pitch discrimination was investigated. The mismatch negativity (MMN) component was recorded from reading subjects to pitch changes of identical magnitude in pure tones with only one sinusoidal frequency component and in spectrally rich tones with two additional harmonic partials. In a separate condition, subjects were asked to indicate detection of pitch change by a button press. The MMN was elicited with a larger amplitude and shorter latency by change in spectrally rich tones than by change in pure tones. Furthermore, the subjects' behavioral responses were more accurate for spectrally rich tones than for sinusoidal tones. Together these data indicate that pre-attentive and attentive pitch discrimination is facilitated with spectrally rich sounds in comparison to pure sinusoidal tones.

Adolescent↗

Pitch and pitch discrimination of broadband signals with rippled power spectra.

A random-interval pulse train or wide-band noise when delayed (tau) and added back to itself (cos+) produces a stimulus with a consinusoidally varying (or trippled) power spectrum. The spacing between the peaks in the spectrum is equal to the reciprocal of the delay (1/tau). If the stimulus is delayed and added back at 180 degrees phase reversal (cos-), then a cosinusoidally varying power spectrum is generated whose spectral peaks are separated by 1/tau, but whose peaks are displaced by 1/2tau relative to the power spectrum of the cos+ stimulus generated with the same day, tau. These stimuli yield a pitch, such that the pitch of the cos+ stimulus is equal to approximately 1/tau and the pitches of the cos- stimuli are equal to approximately 0.9/tau and 1.1/tau. These pitch matching results were studied using a variety of matching stimuli and conditions. Following the identification of the pitches, a method of limits and a same-different procedure were used to study the pitch discriminability of both the cos+ and cos- stimuli. Delays (tau) ranging from 1 to 10 ms were studied covering a pitch range of 90-1100 Hz. The pitch discriminations associated with the cos+ and cos- stimuli were essentially the same for both the random-interval pulse train and the wide-band stimuli. These pitch-discrimination results are compared to those associated with a periodic pulse train. The research is also discussed in terms of discriminations of delayed sounds in reverberant environments. These are consistent with assumptions concerning the autocorrelation of the rippled stimuli within the dominant frequency region for pitch perception.

Acoustics↗

A psychophysical measure of pitch discrimination loss resulting from a frequency range constraint in European starlings (Sturnus vulgaris).

Earlier research (Hulse & Cynx, 1985) revealed that a number of species of songbirds acquired a pitch discrimination between rising and falling sequences in an arbitrarily defined training range of frequencies, but then failed to generalize the discrimination to new frequency ranges--a frequency range constraint. The two experiments here provide a psychophysical estimate of how pitch discrimination deteriorated in one species as sequences were stepped out from the training range. The gradient showing loss of discrimination was much sharper than would have been anticipated by stimulus generalization or the training procedures, and appeared unaffected by the removal of rising and falling frequency information. The frequency range constraint and its psychophysical properties have implications both for the analysis of birdsong and the study of animal cognition.

Animals↗

Place pitch discrimination and speech recognition in cochlear implant users.

The considerable variability in speech perception performance among cochlear implant patients makes it difficult to compare the effectiveness of different speech processing strategies. One result is that optimal individualized processor parameter setting is not always achieved. This paper investigates the relationship between place pitch discrimination ability and speech perception to establish whether pitch ranking could be used as an aid in better patient-specific fitting of processors. Three subjects participated in this study. Place pitch discrimination ability was measured and this information was used to design new channel to electrode allocations for each subject. Several allocations were evaluated with speech tests with consonant, vowel and sentence material. It is shown that there is correlation between the perceptual pitch distance between electrodes and speech perception performance. The results indicate that pitch ranking ability might be used both as an indicator of the speech perception potential of an implant user and in the choice of better electrode configurations.

Adult↗

Macaque monkeys discriminate pitch relationships.

This study demonstrates that non-human primates can categorize the direction of the pitch change of tones in a sequence. Two Macaca fascicularis were trained in a positive-reinforcement behavioral paradigm in which they listened to sequences of a variable number of different acoustic items. The training of discriminating pitch direction was divided into three phases with increasing task complexity. In the first two phases, subjects learned to employ a same/different rule. In phase 1, they discriminated acoustic items of different sound quality. Subjects had to respond when there was a change from repeating noise bursts to repeating click trains or vice versa. In phase II, acoustic items differed along one physical dimension only. Subjects had to respond to a change of the frequency of a repeating series of pure tones. In phase III, sequences consisted of three series of repeating tones of different frequency. Subjects were required to respond when the frequency of the tones changed in a downward direction and to refrain from responding when the frequency remained constant or increased. After several ten thousand trials, subjects categorized pitch direction well above chance level. The discrimination was performed over a 4.5-octave range of frequencies and was largely independent of the temporal and ordinal position of the downward pitch direction within the sequence. These results demonstrate that monkeys can recognize pitch relationships and thus that monkeys have the concept of ordinal relations between acoustic items.

Animals↗