Development and validation of the University of Washington Clinical Assessment of Music Perception test.

OBJECTIVES: Assessment of cochlear implant outcomes centers around speech discrimination. Despite dramatic improvements in speech perception, music perception remains a challenge for most cochlear implant users. No standardized test exists to quantify music perception in a clinically practical manner. This study presents the University of Washington Clinical Assessment of Music Perception (CAMP) test as a reliable and valid music perception test for English-speaking, adult cochlear implant users. DESIGN: Forty-two cochlear implant subjects were recruited from the University of Washington Medical Center cochlear implant program and referred by two implant manufacturers. Ten normal-hearing volunteers were drawn from the University of Washington Medical Center and associated campuses. A computer-driven, self-administered test was developed to examine three specific aspects of music perception: pitch direction discrimination, melody recognition, and timbre recognition. The pitch subtest used an adaptive procedure to determine just-noticeable differences for complex tone pitch direction discrimination within the range of 1 to 12 semitones. The melody and timbre subtests assessed recognition of 12 commonly known melodies played with complex tones in an isochronous manner and eight musical instruments playing an identical five-note sequence, respectively. Testing was repeated for cochlear implant subjects to evaluate test-retest reliability. Normal-hearing volunteers were also tested to demonstrate differences in performance in the two populations. RESULTS: For cochlear implant subjects, pitch direction discrimination just-noticeable differences ranged from 1 to 8.0 semitones (Mean = 3.0, SD = 2.3). Melody and timbre recognition ranged from 0 to 94.4% correct (mean = 25.1, SD = 22.2) and 20.8 to 87.5% (mean = 45.3, SD = 16.2), respectively. Each subtest significantly correlated at least moderately with both Consonant-Nucleus-Consonant (CNC) word recognition scores and spondee recognition thresholds in steady state noise and two-talker babble. Intraclass coefficients demonstrating test-retest correlations for pitch, melody, and timbre were 0.85, 0.92, and 0.69, respectively. Normal-hearing volunteers had a mean pitch direction discrimination threshold of 1.0 semitone, the smallest interval tested, and mean melody and timbre recognition scores of 87.5 and 94.2%, respectively. CONCLUSIONS: The CAMP test discriminates a wide range of music perceptual ability in cochlear implant users. Moderate correlations were seen between music test results and both Consonant-Nucleus-Consonant word recognition scores and spondee recognition thresholds in background noise. Test-retest reliability was moderate to strong. The CAMP test provides a reliable and valid metric for a clinically practical, standardized evaluation of music perception in adult cochlear implant users.

Clinical assessment of music perception in cochlear implant listeners.

OBJECTIVE: Cochlear implants (CI) have provided tremendous benefit for speech recognition in quiet for patients with severe and profound hearing impairment, but implant users still have great difficulty perceiving music. The purpose of this study was to develop a test to quantify music perception by CI listeners in a clinically practical manner that could be standardized for administration at any implant center. STUDY DESIGN: Prospective convenience sample. SETTING: Hearing research center at an academic hospital. PATIENTS: Eight CI listeners, including 5 men and 3 women with implant experience ranging from 0.5 to 6 years, participated in this study. They represented a variety of implant devices and strategies. INTERVENTION: Administration of the Clinical Assessment of Music Perception test in a standardized sound field. MAIN OUTCOME MEASURES: Music perception was assessed using a computerized test comprising pitch direction discrimination, melody identification, and timbre identification. The pitch subtest used a 2-alternative forced-choice adaptive procedure to determine a threshold interval for discrimination of complex pitch direction change. The melody and timbre subtests assessed recognition of 12 isochronous melodies and 8 musical instruments, respectively. RESULTS: Testing demonstrated a broad range of perceptual accuracy on all 3 subtests. Test duration averaged less than 45 minutes. CONCLUSION: Clinical Assessment of Music Perception is an efficient computerized test that may be used to measure 3 different aspects of music perception in CI users in a standardized and clinically practical manner.

Discrimination of Schroeder-phase harmonic complexes by normal-hearing and cochlear-implant listeners.

The temporal fine structure (TFS) of sound contributes significantly to the perception of music and speech in noise. The evaluation of new strategies to improve TFS delivery in cochlear implants (CIs) relies upon the assessment of fine structure encoding. Most modern CI sound processing schemes do not encode within-channel TFS per se, but some TFS information is delivered through temporal envelope cues across multiple channels. Positive and negative Schroeder-phase harmonic complexes differ primarily in acoustic TFS and provide a potential test of TFS discrimination ability in CI users for current and future processing strategies. The ability to discriminate Schroeder-phase stimuli was evaluated in 24 CI users and 7 normal-hearing listeners at four fundamental frequencies: 50, 100, 200, and 400 Hz. The dependent variables were percent correct at each fundamental frequency, average score across all fundamental frequencies, and a maximum-likelihood-predicted threshold fundamental frequency for 75% correct. CI listeners scored better than chance for all fundamental frequencies tested. The 50-Hz, average, and predicted threshold scores correlated significantly with consonant-nucleus-consonant word scores. The 200-Hz score correlated with a measure of speech perception in speech-shaped noise. Pitch-direction sensitivity is predicted jointly by the 400-Hz Schroeder score and a spectral ripple discrimination task. The results demonstrate that the Schroeder test is a potentially useful measure of clinically relevant temporal processing abilities in CI users.