Effect of frequency, timbre, experience, and feedback on musical tuning skills

Experienced and Inexperienced Listeners' Perception of Vocal Strain

OBJECTIVE

The ability to perceive strain or tension in a voice is critical for both speech-language pathologists and singing teachers. Research on voice quality has focused primarily on the perception of breathiness or roughness. The perception of vocal strain has not been extensively researched and is poorly understood.

METHODS/DESIGN

This study employs a group and a within-subject design. Synthetic female sung stimuli were created that varied in source slope and vocal tract transfer function. Two groups of listeners, inexperienced listeners and experienced vocal pedagogues, listened to the stimuli and rated the perceived strain using a visual analog scale Synthetic female stimuli were constructed on the vowel /ɑ/ at 2 pitches, A3 and F5, using glottal source slopes that drop in amplitude at constant rates varying from - 6 dB/octave to - 18 dB/octave. All stimuli were filtered using three vocal tract transfer functions, one derived from a lyric/coloratura soprano, one derived from a mezzo-soprano, and a third that has resonance frequencies mid-way between the two. Listeners heard the stimuli over headphones and rated them on a scale from "no strain" to "very strained" using a visual-analog scale.

RESULTS

Spectral source slope was strongly related to the perception of strain in both groups of listeners. Experienced listeners' perception of strain was also related to formant pattern, while inexperienced listeners' perception of strain was also related to pitch.

CONCLUSION

This study has shown that spectral source slope can be a powerful cue to the perception of strain. However, inexperienced and experienced listeners also differ from each other in how strain is perceived across speaking and singing pitches. These differences may be based on both experience and the goals of the listener.

Drop-off Detection with the Long Cane: Effects of Different Cane Techniques on Performance

This study compared the drop-off detection performance with the two-point touch and constant contact cane techniques using a repeated-measures design with a convenience sample of 15 cane users with visual impairments. The constant contact technique was superior to the two-point touch technique in the drop-off detection rate and the 50% detection threshold. The findings may help an orientation and mobility instructor select an appropriate technique for a particular client or training situation.

Can Inexperienced Listeners Hear Who Is Flat? The Role of Timbre and Vibrato

OBJECTIVES/HYPOTHESIS

Research has shown that the distribution of spectral energy and the presence of vibrato in a complex tone can affect pitch perception. This study sought to answer the questions: "Does timbre affect the perception of difference in pitch in complex synthetic stimuli modeled after singing voices?" "Does vibrato affect the perception of difference in pitch in complex synthetic stimuli modeled after singing voices?" and "Does the direction of timbre difference affect the perception of pitch difference?"

STUDY DESIGN

This is a repeated-measures factorial design.

METHODS

The experiment consisted of three experimental blocks at the pitches A3, G4, and F5, each with a vibrato and no-vibrato subblock. For each block, two reference stimuli (mezzo-soprano and soprano) and six test stimuli (mezzo-soprano at frequencies of -1%, -2%, and -3%, soprano at frequencies of -1%, -2%, and -3%) were synthesized on the vowel /ɑ/. Each reference stimulus was paired with itself, with the other reference stimulus, and with all the test stimuli. Vibrato stimuli had a rate of 5.6 Hz and a frequency vibrato extent of ±50 cents. Listeners indicated the degree to which stimuli differed in pitch.

RESULTS

Differences in timbre and vibrato were significant main effects on the perception of pitch difference. The direction of timbre difference was a consistent significant effect on the perception of pitch difference for the pitch G4; however, this was not a consistent effect at the pitches A3 and F5.

CONCLUSION

Numerous factors can affect the perception of pitch including timbre and presence of vibrato.

The Effect of Timbre, Pitch, and Vibrato on Vocal Pitch-Matching Accuracy

OBJECTIVE/HYPOTHESIS

This study seeks to examine how target stimulus timbre, vibrato, pitch, and singer classification affect pitch-matching accuracy.

STUDY DESIGN

This is a repeated-measures factorial design.

METHODS

Source signals were synthesized with a source slope of -12 dB/octave with and without vibrato at each of the pitches, C4, B4, and F5. These source signals were filtered using five formant patterns (A-E) constituting a total of 30 stimuli (5 formant patterns × 3 pitches × 2 vibrato conditions). Twelve sopranos and 11 mezzo-sopranos with at least 3 years of individual voice training were recruited from the University Of Tennessee, Knoxville, School of Music and the Knoxville Opera Company. Each singer attempted to match the pitch of all 30 stimuli presented twice in a random order.

RESULTS

Results indicated that there was no significant effect of formant pattern on pitch-matching accuracy. With increasing pitch from C4 to F5, pitch-matching accuracy increased in midpoint of the vowel condition but not in prephonatory set condition. Mezzo-sopranos moved toward being in tune from prephonatory to midpoint of the vowel. However, sopranos at C4 sang closer to being in tune at prephonatory but lowered the pitch at the midpoint of the vowel. Presence or absence of vibrato did not affect the pitch-matching accuracy. However, the interesting finding of the study was that singers attempted to match the timbre of stimuli with vibrato.

CONCLUSIONS

The results of this study show that pitch matching is a complex process affected by many parameters.

Pitch and timbre interfere when both are parametrically varied

Pitch and timbre perception are both based on the frequency content of sound, but previous perceptual experiments have disagreed about whether these two dimensions are processed independently from each other. We tested the interaction of pitch and timbre variations using sequential comparisons of sound pairs. Listeners judged whether two sequential sounds were identical along the dimension of either pitch or timbre, while the perceptual distances along both dimensions were parametrically manipulated. Pitch and timbre variations perceptually interfered with each other and the degree of interference was modulated by the magnitude of changes along the un-attended dimension. These results show that pitch and timbre are not orthogonal to each other when both are assessed with parametrically controlled variations.

Interaction Effects of the Amount of Practice, Preferred Cane Technique, and Type of Cane Technique Used on Drop-off Detection Performance

This study examined the interaction effects of the amount of practice and the cane technique used in drop-off detection with a sample of 32 adults who were blind. The advantage of the constant contact technique over the two-point touch technique was significantly greater for the less experienced cane users than for the more experienced ones.

Pitch ranking of complex tones by normally hearing subjects and cochlear implant users

The ability of 10 normally hearing (NH) adults and eight cochlear implant (CI) users to pitch-rank pairs of complex tones was assessed. The acoustically presented stimuli differed in fundamental frequency (F0) by either one or six semitones (F0 range: 98 to 740 Hz). The NH group obtained significantly higher mean scores for both experiments: (NH: one semitone - 81.2%, six semitones - 89.0%; CI: one semitone - 49.0%, six semitones - 60.2%; p<0.001). Prior musical experience was found to be associated with higher pitch-ranking scores for the NH subjects. Those with musical experience ratings <3 obtained significantly lower scores for both interval sizes (p<0.001) than those with higher ratings. Nevertheless, the scores obtained by the musically inexperienced, NH adults were significantly higher than those obtained by the CI group for both the one-semitone (p=0.022) and six-semitone (p=0.018) intervals. These results suggest that the pitch information CI users obtain from their implant systems is less accurate than that obtained by NH listeners when listening to the same complex sounds. Furthermore, the relatively poor pitch-ranking ability of at least some CI users may be associated with a more-limited experience of music in general.

The relationship between vocal pitch-matching skills and pitch discrimination skills in untrained accurate and inaccurate singers

Few studies have compared the relationship between pitch discrimination accuracy and the accuracy of fundamental frequency (F(o)) control. This study investigated the relationship between vocal pitch-matching skills, which is one method of testing F(o) control, and pitch discrimination skills in untrained accurate and inaccurate singers, and the effect of timbre on their pitch discrimination accuracy. Data showed that accurate singers had more precise discrimination and pitch-matching abilities compared with their inaccurate counterparts. Pitch discrimination was differentially affected by the timbre (eg, spectral differences) of comparison tones. In addition, results showed a significant relationship between pitch discrimination abilities and pitch-matching accuracy. The results suggest that accurate F(o) control is at least partially dependent on pitch discrimination abilities, which are important for accurate singing.

Influence of tonal context and timbral variation on perception of pitch

In this study, spectral timbre's effect on pitch perception is examined in varying contexts. In two experiments, subjects detected pitch deviations of tones differing in brightness in an isolated context in which they compared two tones, in a tone-series context in which they judged whether the last tone of a simple sequence was in or out of tune, and in a melodic context in which they determined whether the last note of familiar melodies was in or out of tune. Timbre influenced pitch judgments in all the conditions, but increasing tonal context allowed the subjects to extract pitch information more accurately. This appears to be due to two factors: (1) The presence of extra tones creates a stronger reference point from which to judge pitch, and (2) the melodies' tonal structure gives more cues that facilitate pitch extraction, even in the face of conflicting spectral information.

Pulse rate matching by cochlear implant patients: effects of loudness randomization and electrode position

OBJECTIVE

To assess the accuracy with which cochlear implant patients are able to match two stimuli on the basis of pulse rate pitch.

DESIGN

Patients were required to adjust the pulse rate of a comparison stimulus to match that of a fixed reference stimulus. The comparison and the reference stimuli differed in loudness or were presented to different electrodes.

RESULTS

Patients were able to match stimuli on the basis of pulse rate, with varying degrees of accuracy. Deviations from the target and the amount of variability were greater when stimuli were presented to different electrodes. The results also provide evidence regarding level-dependent pitch shifts.

CONCLUSIONS

Because of methodological limitations, conclusions regarding pitch equivalence are limited. However, patients vary significantly in their ability to utilize temporal information.

Effects of harmonics on relative pitch discrimination in a musical context

The contribution of different harmonics to pitch salience in a musical context was examined by requiring subjects to discriminate a small (1/4 semitone) pitch change in one note of a melody that repeated in transposition. In Experiment 1, performance was superior when more harmonics were present (first five vs. fundamental alone) and when the second harmonic (of tones consisting of the first two harmonics) was in tune compared with when it was out of tune. In Experiment 2, the effects of harmonics 6 and 8, which stand in octave-equivalent simple ratios to the fundamental (2:3 and 1:2, respectively) were compared with harmonics 5 and 7, which stand in more complex ratios (4:5 and 4:7, respectively). When the harmonics fused into a single percept (tones consisting of harmonics 1, 2, and one of 5, 6, 7, or 8), performance was higher when harmonics 6 or 8 were present than when harmonics 5 or 7 were present. When the harmonics did not fuse into a single percept (tones consisting of the fundamental and one of 5, 6, 7, or 8), there was no effect of ratio simplicity.

Tuning of diatonic scales by violinists, pianists, and nonmusicians

The present study shows that playing a particular musical instrument influences tuning preference. Violinists (n = 7), pianists (n = 7), and nonmusicians (n = 10) were required to adjust three notes (E, A, and B) in computer-generated, eight-tone ascending and descending diatonic scales of C major. The results indicated that (1) violinists set the three tones closer to Pythagorean intonation than do pianists (p < .01), (2) pianists fit closet to equal-tempered intonation (p < .01), and (3) nonmusicians do not show any preference for a specific intonation model. These findings are consistent with the view that tuning preference is determined by musical experience more than by characteristics of the auditory system. The relevance of these results to theories of cultural conditioning and assessment of tonal perception is discussed.

The influence of spectral composition of complex tones and of musical experience on the perceptibility of virtual pitch

A matching paradigm was used to evaluate the influence of the spectral characteristics number, relative height, and density of harmonics on the perceptibility of the missing fundamental. Fifty-eight musicians and 58 nonmusicians were instructed to adjust mistuned sinusoids to the subjectively perceived fundamental pitches of corresponding overtone spectra. Analyses of variance were used to compare the average of absolute and relative deviations of the tunings from the highest common divisors of the complex tones. The results indicate that musical experience is the most influential single factor determining the assessment of fundamental pitch. Nevertheless, all spectral parameters significantly affect tuning performance. Systematic relative deviations (stretching/compression effects) were observed for all considered variables. An increase of the optimum subjective distance between an overtone spectrum and its corresponding fundamental was characteristic of musicians and unambiguous spectra, whereas the compression effect was typical of nonmusicians and complex tones containing spectral gaps.

Pitch interactions in the perception of isolated musical triads

In previous work done in our laboratory, we have investigated the perceived pitch class of isolated musical triads. We have found that as the amount of musical training increased, listeners perceptions progress, from very confused percepts of pitch class, to analytic percepts corresponding to the pitch class of the highest note in the triad, and finally to synthetic percepts corresponding to the root note for the more harmonic triad types. In the present work, we used a pitch matching technique to determine the actual pitch, rather than merely the pitch class, perceived when listeners analytically "hear out" a particular note in a major triad. There was a strong tendency for the pitch of the analytically perceived note to be displaced by as much as 60 cents in the direction of the other notes in the triad. The magnitude of this effect decreased as musical training increased, and it was also affected by the relative salience of the individual triad notes. These results have implications for the mechanism of triad perception, and for claims regarding the harmonic equivalence of triad inversions.