Psychoacoustic abilities associated with music perception in cochlear implant users

Abstract

Objectives: This study was designed to determine what acoustic elements are associated with musical perception ability in cochlear implant (CI) users and to understand how acoustic elements, which are important to good speech perception, contribute to music perception in CI users. It was hypothesized that the variability in the performance of music and speech perception may be related to differences in the sensitivity to specific acoustic features such as spectral changes or temporal modulations, or both.

Design: A battery of hearing tasks was administered to 42 CI listeners. The Clinical Assessment of Music Perception was used, which evaluates complex-tone pitch-direction discrimination, melody recognition, and timbre recognition. To investigate spectral and temporal processing, spectral-ripple discrimination and Schroeder-phase discrimination abilities were evaluated. Speech perception ability in quiet and noise was also evaluated. Relationships between Clinical Assessment of Music Perception subtest scores, spectral-ripple discrimination thresholds, Schroeder-phase discrimination scores, and speech recognition scores were assessed.

Results: Spectral-ripple discrimination was shown to correlate with all three aspects of music perception studied. Schroeder-phase discrimination was generally not predictive of music perception outcomes. Music perception ability was significantly correlated with speech perception ability. Nearly half of the variance in melody and timbre recognition was predicted jointly by spectral-ripple and pitch-direction discrimination thresholds. Similar results were observed on speech recognition as well.

Conclusions: This study suggests that spectral-ripple discrimination is significantly associated with music perception in CI users. A previous report showed that spectral-ripple discrimination is significantly correlated with speech recognition in quiet and in noise. This study also showed that speech recognition and music perception are also related to one another. Spectral-ripple discrimination ability seems to reflect a wide range of hearing abilities in CI users. The results suggest that materially improving spectral resolution could provide significant benefits in music and speech perception outcomes in CI users.

Figure 1

Relationship between spectral-ripple discrimination and pitch-direction discrimination. Linear regression is represented by the solid line.

Figure 2

Relationship between spectral-ripple thresholds and melody scores (left panel) and timbre scores (right panel). Linear regressions are represented by the solid lines.

Figure 3

Left panel shows the multiple regressions for melody recognition using spectral-ripple thresholds and mean pitch-direction thresholds (r = 0.72, adjusted R² = 0.49, p < 0.0001; whereas, independently, R² = 0.42, p < 0.0001 and R² = 0.34, p < 0.0001 for spectral-ripple and mean pitch-direction discrimination thresholds, respectively). Right panel shows the multiple regressions for timbre recognition using spectral-ripple thresholds and mean pitch-direction thresholds (r = 0.70, adjusted R²=0.47, p < 0.0001; whereas, independently, R² = 0.32, p < 0.0001 and R² = 0.41, p < 0.0001 for spectral-ripple and mean pitch-direction discrimination thresholds, respectively). Linear regressions between the true and predicted scores are represented by the solid lines.

Figure 4

Relationship between mean pitch thresholds and CNC scores (left panel), SRTs in two-talker babble (middle panel), and SRTs in steady-state noise (right panel). Linear regressions are represented by the solid lines.

Figure 5

Relationship between CNC scores and melody recognition scores (left panel) and timbre recognition scores (right panel). Linear regressions are represented by the solid lines.

Figure 6

Relationship between SRTs and melody scores (left panel) and timbre scores (right panel). Linear regressions are represented by the solid lines.

Figure 7

Sound processor output for spectral-ripple densities of 0.5, 1.0, 2.0, and 4.0 ripples/octave with standard ripple (filled circles) and inverted ripple (open circles). Electrode 16 represents for the highest channel.