Marsha G. Clarkson

Infant pitch perception: Evidence for responding to pitch categories and the missing fundamental

While numerous studies on infant perception have demonstrated the infants ability to discriminate sounds having different frequencies, little research has evaluated more sophisticated pitch perception abilities such as perceptual constancy and perception of the missing fundamental. In the present study 7-8-month-old infants demonstrated the ability to discriminate harmonic complexes from two pitch categories that differed in pitch by approximately 20% (e.g., 160 vs 200 Hz). Using a visually reinforced conditioned head-turning paradigm, a number of spectrally different tonal complexes that contained varying harmonic components but signaled the same two pitch categories were presented. After learning the basic pitch discrimination, the same infants learned to categorize spectrally different tonal complexes according to the pitches signaled by their fundamental frequencies. That is, the infants showed evidence of perceptual constancy for the pitch of harmonic complexes. Finally, infants heard tonal complexes that signaled the same pitch categories but for which the fundamental frequency was removed. Infants were still able to categorize the harmonic complexes according to their pitch categories. These results suggest that by 7 months of age infants show fairly sophisticated pitch perception abilities similar to those demonstrated by adults.

When they were very young: Almost-threes remember two years ago☆

Abstract Five children who had participated 15–19 times between 6–40 weeks of age in a study of the perception of auditory space returned to the laboratory two years later. The original experimental sequence, which entailed trials in both light and darkness, was carried out along with several additional memory probes. Five control subjects, age, and sex mates who had not previously participated, also experienced the test procedure. Behavior was videotaped and recorded by two observers, and the control and experimental groups were compared on a series of measures. Several measures provide indications that the 2-year-olds remembered what they did in the laboratory two years before; specifically, they retained memory for early action sequences. The findings are of particular interest because a transition from preverbal to verbal functioning marks this 2-year period of development.

Auditory Backward Masking Deficits in Children with Reading Disabilities.

Studies evaluating temporal auditory processing among individuals with reading and other language deficits have yielded inconsistent findings due to methodological problems () and sample differences. In the current study, seven auditory masking thresholds were measured in fifty-two 7- to 10-year-old children (26 diagnosed with reading disability [RD], 26 without reading disability). Hierarchic multiple regression analyses indicated that RD status predicted performance only in the backward-bandpass noise (p<.05) and backward notched-noise conditions (p<.05), suggesting both temporal and spectral auditory processing deficits. These results suggest that any auditory deficit associated with RD may be more complex than previously hypothesized.

Infants’ pitch perception: Masking by low- and high-frequency noises

The present research employed an operant conditioning procedure typically used with infants to test noise masking of pure tones and tonal complexes in adults and in 7-month-old infants. Adults and infants were presented with either pure tones of 160 and 200 Hz or harmonic tonal complexes with pitches equivalent to 160 and 200 Hz. The tonal complexes did not contain energy at the fundamental frequency. After learning these tasks, subjects in the tonal complex group categorized spectrally varying tonal complexes according to the pitch of the missing fundamental. Stimuli were subsequently presented in combination with either a low- or a high-frequency noise. Both age groups successfully discriminated pure tones when combined with a high-frequency noise but not when combined with a low-frequency noise in the same frequency range as the pure tone. Infants, like adults, successfully categorized harmonic tonal complexes based on the pitch of the missing fundamental when those stimuli were combined with a low-frequency noise in the range of the missing fundamental but not when combined with a high-frequency noise which covered the frequency range of the harmonics themselves. These results suggest that infants rely primarily on a central process and not peripherally generated combination tones to hear the pitch of the missing fundamental.

Infant timbre perception: Discrimination of spectral envelopes

Seven-month-old infants were trained to discriminate the timbre of tonal complexes that differed in their spectral envelopes. In a conditioned head-turning paradigm, infants initially learned to discriminate stimuli that had the same fundamental frequency, 200 Hz, but different harmonic components (Le., frequencies). After successfully completing the basic timbre discrimination, the same infants learned to discriminate less salient stimuli from which the fundamental frequency had been removed. These results suggest that young infants can analyze the spectra of tonal complexes and discriminate differences in one of the most important cues for timbre perception in adults, the spectral envelope.

The effects of sound duration on newborns' head orientation ☆

Two experiments assessed the importance of sound duration for eliciting head orientation responses from newborn infants. In Experiment 1, thirty infants turned with equal frequency toward 20-s continuous rattle sounds and 20-s trains of rattle segments. The duration of the rattle segments--14 and 100 ms (2/s), or 500 ms (1/s)--did not influence the likelihood of turning. Response latencies and durations proved quite similar for all stimuli. In Experiment 2, twenty-four infants heard continuous rattle sounds of four different durations: 1, 5, 10, and 20 s. They turned reliably to all stimulus durations; furthermore, the magnitude and temporal characteristics of head orientation responses did not differ for the four stimulus durations. These results suggest that the newborns head orientation response may reflect a motor program that is initiated by auditory input and then executed in a similar fashion regardless of further stimulation.

STIMULUS-PRESENTATION PROBABILITY INFLUENCES NEWBORNS' HEAD ORIENTATION TO SOUND^

Although newborn infants are capable of turning their heads toward laterally-presented sounds, the incidence of such responding varies across studies. Previous work suggests that as the probability of a laterally-presented sound increases head-turning performance improves. To test this “lateral-stimulus-presentation probability” hypothesis, we presented 30 alert newborns with a rattle sound from a lateral source on either 1/4, 2/4, or 3/4 of all sound trials. On remaining sound trials the rattle came from a loudspeaker located above the infants head. For 12 infants all lateral trials were presented consecutively; these trials were spaced across the session for the other infants. The likelihood of correct head turning increased linearly as the lateral-stimulus-presentation probability increased. The distribution of lateral trials did not influence the incidence of correct head turning.

Infants’ perception of the pitch of rippled noise

Previous research has revealed qualitative parallels between infants’ and adults’ perception of the pitch of the missing fundamental, yet it is unclear whether infants’ performance is quantitatively the same as adults’. To begin to quantify some aspects of infants’ pitch processing, 7‐month‐old infants’ detection of an iterated rippled noise (IRN) was tested in a conditional head‐turn procedure. A 500‐ms Gaussian noise was repeated at a rate of 1/s, and infants learned to turn their heads when an IRN (with a delay of 2 ms, no attenuation applied to the delayed signal, and 16 iterations) was presented for 6 s. The parameters of the IRN represented a delay that is in the middle of the ‘‘best’’ pitch range for adults; an attenuation that produces the strongest pitch for adults; and a number of iterations that provides a very clear pitch for adults. Throughout testing the overall stimulus level roved from 63 to 67 dBA (over a background of 28 dBA). All infants reliably detected the introduction of the ripple ...

Relationships between timing in reading and language ability and auditory temporal masking.

Broad timing difficulties may play a role in reading problems, but its role and a potential relationship with auditory temporal processing are unclear. The present study explored relationships between variables that might identify timing as a possible link between reading and auditory temporal masking. Tone identification thresholds were measured for 75 adults for backward masking and comodulation masking release (CMR) stimuli. Adults also completed a battery of nonverbal IQ, naming speed, motor speed, language, and reading measures. Backward masking stimuli consisted of a 20‐ms, 1‐kHz tone immediately preceding a 300‐ms, 600–1400 Hz bandpass noise masker. A notched‐noise condition included a spectral notch between 800 and 1200 Hz. CMR stimuli consisted of a reference condition in which a 1‐kHz tone was temporally centered in a 20‐Hz wide narrow‐band modulated noise masker alone and one with eight flanking bands of modulated noise in adjacent frequency regions present. CMR was measured as the improvement ...

Relationship between reading and language ability and auditory temporal processing measured with the precedence effect

Processing of timing information by the auditory system contributes to numerous abilities, including spatial hearing and higher‐order language and reading skills. However, relationships among these abilities are poorly understood. The present study was aimed at investigating potential common mechanisms that involve timing. Auditory timing was measured by click stimuli presented via two loudspeakers at a rate of 1.5/sec. Fourteen‐ms clicks were presented from one (single‐source condition) or two (dual‐source condition) loudspeakers. In the latter condition, the onset of one loudspeaker was delayed relative to the other by 5, 10, 20, 50, 100, 200, or 400 ms. Seventy‐five naive adults (mean age 21.23 years) listened to the auditory stimuli and were asked to identify the source of the leading sound. Additionally, all participants completed a battery of language and reading measures. Results on the auditory task revealed that performance was significantly above chance on single‐source trials, dropped at short ...