Punita Singh - Academia.edu (original) (raw)

Papers by Punita Singh

The Journal of the Acoustical Society of America, 1989

The dual nature of pitch (“spectral”/“virtual”) and its relation to such timbral percepts as “sha... more The dual nature of pitch (“spectral”/“virtual”) and its relation to such timbral percepts as “sharpness” and “roughness” is explored in a set of experiments designed to ascertain perceptual cues facilitating discrimination tasks with complex tones having flat spectral envelopes. Three types of complexes are employed: (1) harmonic “residue” tones comprising four harmonics, (2) ten-component harmonic and inharmonic complexes with all components shifted from some reference frequency, and (3) ten-component complexes with a single component shifted from its harmonic frequency. Using two-tone sequences as stimuli, listeners are asked to judge if the second tone is (1) the same, (2) higher in pitch, (3) lower in pitch, (4) different in “something else,” (5) different in “something else” and higher, or (6) diffferent in “something else” and lower in pitch than the first (“something else” is taken to be synonymous with “timbre”). For residue tones, data indicate that changes in spectral locu...

Journal of the Acoustical Society of America, Nov 1, 1989

Journal of the Acoustical Society of America, Apr 1, 1991

Journal of the Acoustical Society of America, Apr 1, 1985

Journal of the Acoustical Society of America, Nov 1, 2013

Rhythms on the tabla, a north Indian percussion instrument, are generated by producing sounds on ... more Rhythms on the tabla, a north Indian percussion instrument, are generated by producing sounds on one or two drums separately or simultaneously to produce simple or compound “bols.” At high speeds, auditory stream segregation based on spectral properties of adjacent bols can create parallel perceptual layers that can be leveraged strategically by percussionists. This observed phenomenon was studied experimentally by constructing sequences of bols in which adjacent sounds shared different spectral regions. For example, the bols “ghe” and “tin,” which have very different spectra, were placed on either side of the compound bol “dhin,” which contains both “ghe” and “tin.” At a moderate tempo, the sequence is typically heard as a gallop rhythm. However, at quicker tempi, streaming occurs and components of the compound bol “dhin” group perceptually with their neighboring counterparts, to create parallel layers of pairs of “ghe,” “ghe” and “tin,” “tin”, instead of the galloping triple. Listeners identified when streaming took place as a function of the specific bols and tempi used. Spectral analyses of the bols indicated that perceptual segregation was indeed based on proximity of spectral loci. At high speeds, spectral differences are perceptually highlighted and facilitate the formation of auditory streams.

Journal of the Acoustical Society of America, Apr 1, 1993

Spectral factors such as differences in harmonic content are powerful cues in the organization of... more Spectral factors such as differences in harmonic content are powerful cues in the organization of tonal sequences. Temporal factors such as rise time, however, have been shown to be poor cues [W. M. Hartmann and D. Johnson, Mus. Perc. 9(2), 155–184 (1991)]. The relative salience of these factors was investigated further using complex tones sequenced in a repeating ABA-‘‘gallop’’ format, under conditions in which tones A and B had the same, or different harmonic content and/or temporal envelope shape. The F0 difference between A and B was initially 0 Hz, but increased over the course of a trial, until terminated by a listener, indicating perceptual segregation of the input sequence into sub-sequences comprising A and B tones, respectively. The F0 difference required to reach this segregation threshold provided a measure of the efficacy of stimulus features of A and B as cues for sequential organization. Sequences combining differences in spectral content and temporal envelope shape required the smallest F0 change for segregation. Sequences of tones with the same harmonic structure and temporal envelope required the largest F0 changes, while the other conditions fell in the middle of this range. Results will be discussed in terms of implications for sequential organization as well as for the perception of timbre. [Work supported by NSERC, Canada.]

Proceedings of Meetings on Acoustics, 2013

The use of 'chikari' strings on instruments such as the sitar and sarod manifests principles of A... more The use of 'chikari' strings on instruments such as the sitar and sarod manifests principles of Auditory Scene Analysis in creating a harmonic reference, melodic contrast and rhythmic accompaniment. Unlike the principal 'baj' strings on which the main melody is played, or resonant 'tarb' strings that reinforce volume, the 'chikari' strings are sounded at strategic points in performance to provide a drone, add texture, outline chords, mark rhythmic positions and keep tempo. Listening and transcription experiments conducted with recordings of interleaved notes played on 'chikari' and 'baj' strings validate how differences in their timbre and tuning help to keep them perceptually apart while forming more coherent patterns based on timbre similarity and pitch proximity. Such grouping and segregation can affect the perception of temporal order, maintain the illusion of melodic continuity and in some cases of virtual polyphony. These observations add to the growing body of evidence supporting the role of timbre as a structural dimension of music and illustrate how a single instrument can bring about orchestral effects via the strategic use of devices such as 'chikari' strings.

Journal of the Acoustical Society of America, Oct 1, 1997

Spectral factors such as differences in harmonic content are powerful cues in the perceptual orga... more Spectral factors such as differences in harmonic content are powerful cues in the perceptual organization of tone sequences. Temporal features such as rise time, however, have been shown to be poor cues ͓W. M. Hartmann and D. Johnson, Mus. Perc. 9, 155-184 ͑1991͔͒. The relative influence of these timbral features on perceptual segregation was investigated. Complex tones were sequenced in a repeating ABA-''gallop'' format, under four conditions in which tones A and B had the same or different timbres as defined by differences in numbers of harmonics and temporal-envelope features. A sequence started with A and B tones at the same F0. The F0 difference between A and B then increased over the course of a trial, until a listener terminated the trial indicating perceptual segregation into sub-sequences comprising A and B tones, respectively. The F0 difference required to reach this crossover point of segregation provided a measure of the efficacy of stimulus features of A and B as cues for perceptual organization. Sequences combining differences in harmonic structure and temporal envelope required the smallest F0 change for segregation. Sequences of tones with the same harmonic structure and temporal envelope required larger changes in F0, while the other conditions fell in the middle of this range. The F0-tracking method used in this study facilitates measurement of the relative contribution of different stimulus features to stream segregation. It also holds potential as a tool using the point of segregation as a measure of the magnitude of timbre differences brought about by different physical features of sounds.

Journal of the Acoustical Society of America, Apr 1, 1992

Journal of the Acoustical Society of America, Nov 1, 1992

Harmonic complex tones comprising components in different spectral regions may differ considerabl... more Harmonic complex tones comprising components in different spectral regions may differ considerably in timbre. While the pitch of ‘‘residue’’ tones of this type has been studied extensively, their timbral properties have received little attention. Discrimination of F0 for such tones is typically poorer than for complex tones with ‘‘corresponding’’ harmonics [A. Faulkner, J. Acoust. Soc. Am. 78, 1993–2004 (1985)]. The F0 DLs may be higher because timbre differences impair pitch discrimination. The present experiment explores effects of changes in spectral locus and F0 of harmonic complex tones on both pitch and timbre. Six normally hearing listeners indicated if the second tone of a two-tone sequence was: (1) same, (2) higher in pitch, (3) lower in pitch, (4) same in pitch but different in ‘‘something else,’’ (5) higher in pitch and different in ‘‘something else,’’ or (6) lower in pitch and different in ‘‘something else’’ than the first. (‘‘Something else’’ is assumed to represent timbre.) The tones varied in spectral loci of four equal-amplitude harmonics m, m+1, m+2, and m+3 (m=1,2,3,4,5,6) and ranged in F0 from 200 to 200±2n Hz (n=0,1,2,4,8,16,32). Results show that changes in F0 primarily affect pitch, and changes in spectral locus primarily affect timbre. However, a change in spectral locus can also influence pitch. The direction of locus change was reported as the direction of pitch change, despite no change in F0 or changes in F0 in the opposite direction for ΔF0≤0−2%. This implies that listeners may be attending to the ‘‘spectral pitch’’ of components, or to changes in a timbral attribute like ‘‘sharpness,’’ which are construed as changes in overall pitch in the absence of strong F0 cues. For ΔF0≥2%, the direction of reported pitch change accorded with the direction of F0 change, but the locus change continued to be reported as a timbre change. Rather than spectral-pitch matching of corresponding components, a context-dependent spectral evaluation process is thus implied in discernment of changes in pitch and timbre. Relative magnitudes of change in derived features of the spectrum such as harmonic number and F0, and absolute features such as spectral frequencies are compared. What is called ‘‘spectral pitch,’’ contributes to the overall pitch, but also appears to be an important dimension of the multidimensional percept, timbre.

Journal of the Acoustical Society of America, Oct 1, 1992

Perceptual judgments of the presence or absence of tones embedded in modulated noise maskers were... more Perceptual judgments of the presence or absence of tones embedded in modulated noise maskers were obtained using a six-point rating scale (1=clearly absent, 6=clearly present). The maskers comprised four simultaneous noise bands centered at 500, 1000, 1500, and 2000 Hz, with bandwidths of all bands either 12.5, 25, 50, or 100 Hz. The bands were derived either from the same noise source by filtering and transposition, or from different sources, and were subsequently multiplied by same or different (phase shifted) modulators. A sine tone at the center frequency of one of the noise bands was used as the signal. A single noise interval was preceded by a cue tone that was either present or absent in the noise at a fixed S/N≊−13 dB SPL. The cue and noise intervals were both 400 ms long, and separated by 1 s of silence. Rating scores from ten normally hearing listeners were generally higher for tones embedded in maskers with common envelopes, indicating less masking and improved perceptual clarity of the tones. Common origin of noise source did not lead to improved audibility of the tones. There was no significant effect of tone frequency. However, bandwidth affected judgments significantly. For the 12.5- and 25-Hz bandwidths, the difference between modulation conditions was reduced, while false alarm rate increased substantially. These narrow-band noises apparently sounded tonal even in the absence of the signal, thereby receiving higher ratings. For the 50- and 100-Hz-wide maskers, the effect of modulation pattern was enhanced, and there were fewer false alarms. Similarity of amplitude envelopes within a masker has been invoked as a simultaneous grouping cue facilitating segregation of a concurrent signal. It seems that sequential grouping factors such as similarity of perceptual attributes (e.g., pitch or timbre) of the cue and masker also play a role in signal detection. [Work supported by NSERC.]

The Journal of the Acoustical Society of America, 1985

Rapidly occurring sequences comprising sounds that differ along some dimension can often be perce... more Rapidly occurring sequences comprising sounds that differ along some dimension can often be perceptually grouped into subsequences or “streams.” A study demonstrating the use of differences in timbre to provide a basis for stream segregation used four-tone sequences of the type: TxPx TyPx TxPy TyPy, where T and P refer to the timbre and pitch attributes of the complex tones. Forty-nine such sequences were constructed, with the first pair of tones having same pitch Px, but different timbres, and the second pair having pitch Py, and similarly differing timbres. The absolute position of the spectrum was varied to provide timbral “distances” between sounds, and relative spacing between harmonics varied to provide differences in pitch. Six listeners indicated their perceived grouping of the patterns, as being based on pitch, on timbral segregation, or ambiguous groupings not dominated by either cue. Results indicate that differences in spectra affecting either the timbre of the tones, or...

The Journal of the Acoustical Society of America, 1993

The Journal of the Acoustical Society of America, 1992

The Journal of the Acoustical Society of America, 1991

The nature of pitch as a dual attribute comprising both “place” and “period” aspects was dramatic... more The nature of pitch as a dual attribute comprising both “place” and “period” aspects was dramatically illustrated by Licklider [J. Acoust. Soc. Am. 26, 945 (1954)] in his famous masking demonstration. Listener confusions in judgments of pitch in subsequent experiments could be attributed to conflicting “place” and “period” information. Although the concept of pitch duality has been updated by pitch theorists, one aspect that has been consistently overlooked is the relation between “place” or “spectral” pitch and timbre. For example, the direction of a perceived pitch change is often confused with an ordinal aspect of timbre, like “brightness” and “sharpness.” The connection between “place” pitch and timbre will be discussed and demonstrated with examples from the literature and from our own experiments. [Work supported by USAFOSR and NIH.]

The Journal of the Acoustical Society of America, 1997

Perception & Psychophysics, 1990

Journal of the Acoustical Society of America, Nov 1, 1988

within a block of trials. On each trial, the listener heard two sounds (e.g., tone complexes). Th... more within a block of trials. On each trial, the listener heard two sounds (e.g., tone complexes). The values of the variable parameter (e.g., tone frequencies) were drawn from two normal distributions differing only in mean. The listener's task was to identify the sound having the higher mean value of the variable parameter. Discrimination performance was found to be largely independent of the particular physical dimensions along which the sounds varied. Rather, performance appeared to depend primarily on information content of the sounds. Information content was defined in terms of a stimulus equivocation factor that was derived from the data. Based on this model, transmitted information was estimated to be between 1.0-3.0 bits. [Work supported by AFOSR. ] SS17. Comodulation masking release with listening-condition uncertainty.