DOI: 10.7272/q6w957fv
title: Musical consonance-dissonance task in normal hearing and cochlear implant users

description: Hypothesis: This proposed harmonic consonance-dissonance music perception
 task is expected to reveal a monotonic relationship between harmonic
 consonance and pleasantness ratings by NH listeners. Additionally, CI
 recipients will be able to distinguish between the most consonant and most
 dissonant music samples, although with less contrast between each
 condition than the NH cohort and with lower overall ratings of sound
 quality. Finally, we hypothesize that listeners with extensive music
 training would show more pronounced differences in pleasantness ratings
 across the four tiers of consonance to dissonance.  Background:
 Harmonic consonance and dissonance play crucial roles in how music is
 perceived, affecting its perceived quality and pleasantness. However,
 tools to evaluate these musical aspects, especially for CI users, are
 scarce, leading to significant knowledge gaps. This study aimed to refine
 previous methods by emphasizing the variability and typically lower scores
 among CI users, aligning these findings more closely with their reported
 experiences and existing literature. Methods: A total of 34 participants
 (21 NH and 13 CI) completed the 30-minute music task, which involved
 listening to music samples with various levels of harmonic
 consonance-dissonance and then rating the samples on a 5-point
 “pleasantness” scale. Participants also provided details about their
 musical training and listening habits.  Results: Data analysis
 revealed significant differences in how NH and CI users perceive
 consonance and dissonance, particularly when dissonance is pronounced
 enough to be discernible over the spectral resolution limitations of CIs.
 A correlation between formal musical training and better performance on
 the task was observed in both NH and CI groups, suggesting a heightened
 sensitivity to harmonic dissonance among trained listeners. Conclusions:
 The findings challenge prior assumptions about the limited music
 perception capabilities of CI users and propose the potential for a
 shorter, refined version of this test for clinical use or further
 research. This task could aid in optimizing CI configurations for enhanced
 music enjoyment.
description: <strong>Subjects</strong> A group
 of 21 NH listeners, including 13 women and 8 men, with an average age of
 33.5 ± 14.0 (mean ± one standard deviation, range: 24 to 71 years)
 participated in the study (Table 1). Prior to participation, NH subjects
 completed a hearing screening which consisted of responding to pure-tone
 stimuli presented at 25 dB HL at octave intervals from 250 – 8000 Hz in
 each ear. A separate group of 13 CI recipients, including 6 women and 7
 men, were aged 57.4 ± 10.1 years (range: 42 to 77 years) and were
 previously implanted with MED-EL devices. Twelve were unilaterally
 implanted and one was bilaterally implanted, yielding 14 CI ears tested.
 The CI cohort had a distribution of electrode array insertion depths
 ranging from 450 to 673 degrees, with an average of 564 ± 59 deg. Ten ears
 had received a Flex28 (28 mm) array and four ears a FlexSoft (31.5 mm)
 array. All participants completed a music history
 questionnaire outlining the duration, setting, and age of starting music
 training, as well as specific instruments played. Participants were also
 asked how frequently they currently listen to music during an average week
 and what musical genre(s) they prefer.  Among the NH
 cohort, 15 out of 21 subjects reported formal music training; those who
 received music training began at age 8.3 years (± 2.0 years) and lasted
 8.2 years (± 3.2 years). The primary musical instrument studied by each
 subject with musical training was as follows: piano (7), guitar (3),
 violin (2), flute (2), and trombone (1). Five subjects reported currently
 practicing a musical instrument. None reported being self-taught
 musicians. Within the NH cohort, all but one subject reported listening to
 music in their day-to-day life, and there was a wide variability in the
 number of hours per week spent listening to music (18.5 ± 20.2 hours;
 range: 0 to 72 hours/week). When subjects were asked to name their
 favorite genre of music, there was a roughly even mix of respondents
 choosing Hip-Hop, Pop/Rock, Soul/R&B, and Jazz. 
 In the CI cohort, 9 of the 13 subjects reported formal music
 training; those with music training began at age 9.4 years on average (±
 3.2 years) and lasted 11.3 years (± 13.2 years). One subject without
 formal training did report being a self-taught musician, with 10 years of
 practice. The primary instruments included: voice (3), piano (2), violin
 (2), clarinet (1), guitar (1), and bass fiddle (1). Four of the ten are
 still practicing an instrument currently. All but two of the CI recipients
 reported listening to music on a weekly basis, for an average of 14.6 ±
 11.3 hours per week. The CI group’s genre preferences were divided between
 predominantly Folk, Pop/Rock, and Classical.  The
 Institutional Review Board at the University of California, San Francisco
 (UCSF) approved this study and informed consent was obtained from all
 participants. Subjects were recruited from flyers on UCSF campus, from a
 database of potential research volunteers maintained by our lab, and by
 word of mouth. <strong>Musical
 Stimuli</strong> This music sound quality task
 evaluates two aspects of music perception: 1) overall pleasantness of
 synthetic piano music samples and 2) the change in a listener’s rating of
 pleasantness across different levels, or tiers, of harmonic consonance.
 The task was described at length previously in Caldwell et al. (2016),
 which consisted of 3 levels, termed Tier A (most consonant), Tier B, and
 Tier C (most dissonant). For this study, we expanded on the Caldwell et
 al. study to include a fourth level, Tier D, which was more dissonant than
 the previous Tier C.  For this test, we utilized 12
 distinct melodies (2 for practice and 10 for the main test) and paired
 each melody with 4 possible versions of accompanying chord structure,
 resulting in 48 music samples in all. With few exceptions, the notes of
 the melodies were in the treble clef and ranged from F4 - F5 (349 - 698
 Hz) and the chord accompaniments were in the bass clef and ranged from A2
 - E4 (110 - 330 Hz), with harmonics present through around 8000 Hz.
   It may be helpful for the reader to review the
 composition of a single melody with the four versions of chord
 accompaniments in different formats; therefore, these melodies are
 presented in musical score format (Figure 1), spectrogram format (Figure
 2), as well as in an audio file that is available online (Supplementary
 Digital Content 1). For each melody, the accompanying chord structures
 employ varying levels of harmonic dissonance, as follows: 
 Tier A: Consonant major triad with no dissonant notes
 Tier B: One dissonant note (flattened minor 7th replacing the
 consonant 5th in the chord) Tier C: Two dissonant notes
 (flattened minor 6th and 7th replacing the consonant 3rd and
 5th) Tier D: Two dissonant notes (flattened minor 2nd
 and major 2nd replacing the consonant 3rd and 5th)
 Tiers A, B, and C are identical to that which was used in
 previously published work (Caldwell et al., 2016). Tier D was composed
 based on previous studies of varying levels of dissonance (Blood et al.,
 1999), and the degree of pleasantness would then be confirmed through our
 NH listener group. Each music sample was 8 bars in
 length and approximately 14.8 seconds in duration, and were presented at
 the same 130 beats per minute tempo. The intensity of the musical samples
 were normalized to reduce perceived variance in volume across the sample.
 Musical stimuli were generated by GarageBand (Apple Inc., Cupertino, CA,
 USA), utilizing a synthetic piano. <strong>Data
 Collection </strong> The present task was
 administered using an online survey tool (Qualtrics LLC, Seattle, WA,
 USA). At the beginning of the task, listeners were given a practice music
 clip and were asked to adjust the volume of their computer output until
 they achieved a comfortable listening level. For each trial, both practice
 and main test, a listener was presented with a music clip and asked,
 “Ignoring all other aspects of the music, how PLEASANT was the sound?” The
 listener responded by selecting one of the following five options: not at
 all pleasant, slightly pleasant, moderately pleasant, very pleasant, and
 extremely pleasant. Users completed a practice section consisting of 8
 music samples. This subset represented 2 distinct melodies, with all 4
 versions of each melody, so that users could hear the full range of
 consonance-dissonance prior to beginning the test. The remaining 40 music
 samples (10 melodies, 4 versions of each) were used for the final
 assessment. At the end of the task, the respondents were offered a text
 box for providing comments on their experience.  The NH
 cohort listened in the binaural condition with supra-aural headphones. The
 CI cohort streamed the audio from a single test laptop via a MED-EL
 AudioLink to their CI sound processor. All scene classifiers, noise
 reduction algorithms, and microphone directionality features were
 disabled. CI volume was set to 90-100% and sensitivity fixed at 75%. If
 the subject used a hearing device on the contralateral ear then it was
 removed for testing. If there was residual acoustic hearing in the
 contralateral ear, then a foam earplug was inserted.
 For other investigators who may use this test metric for their
 own purposes, the authors recommend taking the frequency range of any
 hearing devices (e.g., hearing aids, CIs, etc.) into consideration. The
 fundamental frequencies of the notes in melodies designed for this
 assessment range from 110 to 700 Hz, while the harmonic content generated
 by the synthetic piano music samples tapered off around 8000 Hz. These
 frequencies are all within the standard frequency allocation table of
 MED-EL CIs (70-8500 Hz), and are mostly within the frequency ranges of
 Cochlear Americas (188-7938 Hz) and Advanced Bionics (250-10,000 Hz) CI
 devices. <strong>Data and Statistical
 Analyses </strong> To assess the impact of
 demographic variables and experiential factors on performance in the
 consonance-dissonance music task, we examined the mean Tier A (most
 consonant) differences among the specified groups. Additionally, we
 analyzed the difference in sound quality ratings from Tier A through Tier
 D (inclusive of all tiers), referred to here as the ‘slope’, which serves
 as a proxy for sensitivity to harmonic dissonance, albeit limited by the
 participants’ overall assessment of pleasantness of musical consonance and
 dissonance. These analyses incorporated variables such as age, musical
 training, and listening habits. We then analyzed the
 differences in performance on the consonance-dissonance music task across
 groups and conditions of interest. For input to the statistical software
 (JASP, Version 0.18.3; Amsterdam, Netherlands) and in all following
 graphs, the five potential responses from listeners were assigned the
 following numerical values: 0 (not at all pleasant), 25 (slightly
 pleasant), 50 (moderately pleasant), 75 (very pleasant), and 100
 (extremely pleasant). To create linear regressions from responses across
 consonance-dissonance tiers, the four tiers were assigned values as
 follows: 100 (Tier A), 66.7 (Tier B), 33.3 (Tier C), and 0 (Tier
 D).  A mixed analysis of variance (ANOVA) was conducted
 on pleasantness ratings of music clips to determine whether the
 within-subject factor of consonance-dissonance tier (Tiers: A, B, C, D)
 affected perception. One between-subject factor (Cohort: NH, CI), was
 included in the model. Mauchly’s test indicated that the assumption of
 sphericity was violated (χ2(5) = 37.1, p &lt; 0.001) and a
 Greenhouse-Geisser correction was applied to the degrees of freedom (ε =
 0.560). Tukey’s test for Honestly Significance Difference (HSD) explored
 all pairwise comparisons, with adjustments made to the p-value for a
 family of 28.  All demographic and CI factors were
 inspected for normal distribution with the Shapiro-Wilk test, and the
 group means tested for differences with either a student’s t-test (if
 parametric) or Mann-Whitney U test (if non-parametric). Correlations of
 these factors with test outcomes were explored with either Pearson’s (for
 parametric) or Spearman’s (for non-parametric) tests.
description: # Harmonic Consonance-Dissonance Study #### **Description of the Data
 File** Top row is headers Each subsequent row is the data from a single
 subject. NH: Normal hearing group CI: Cochlear implant group ID: Subject
 identification code 0A, 1A, 2A, etc.: The number references the melody
 (numbered 0-9) and the letter references the harmonic
 consonance-dissonance tier (A-D). The score listed is from 0-100.  These
 scores represent the following sound quality ratings: (0) "Not at all
 pleasant", (25) "Slightly pleasant", (50) "Moderately
 Pleasant", (75) "Very Pleasant", (100) "Extremely
 Pleasant". YrsMusicalTraining: Years of formal musical training
 reported by subject on a questionnaire. HrsPerWeekListeningToMusic: Hours
 per week of time spent listening to music reported by subject on a
 questionnaire. Duration Of Sev-Prof HL Prior to CI Activation (yrs):
 Duration of severe-to-profound hearing loss prior to cochlear implantation
 activation, in years, a correlate of neural survival in the cochlea
 Angular Insertion Depth (Deg): How deeply inserted the cochlear implant is
 into the cochlea, measured in angular degrees Mismatch E1 (semitones): How
 far the anatomical characteristic frequency of the most apical electrode
 is from the center frequency of the first channel of their cochlear
 implant program E1-4 Error, Average, Signed: The average pitch-place
 mismatch for electrodes 1-4 #### **Music Files & Musical Scores** 12
 melodies (numbered 0-11), 4 tiers of each melody (A, B, C, D) Melodies #10
 and #11 were used for practice only Melodies #0-9 were used for test items