Search

Purpose: The purpose of this study was to investigate musical timbre perception in cochlear-implant (CI) listeners using a multidimensional scaling technique to derive a timbre space. Methods: Sixteen stimuli that synthesized western musical instruments were used (McAdams, Winsberg, Donnadieu, De Soete, & Krimphoff, 1995). Eight CI listeners and 15 normal-hearing (NH) listeners participated. Each listener made judgments of dissimilarity between stimulus pairs. Acoustical analyses that characterized the temporal and spectral characteristics of each stimulus were performed to examine the psychophysical nature of each perceptual dimension. Results: For NH listeners, the timbre space was best represented in three dimensions, one correlated with the temporal envelope (log-attack time) of the stimuli, one correlated with the spectral envelope (spectral centroid), and one correlated with the spectral fine structure (spectral irregularity) of the stimuli. The timbre space from CI listeners, however, was best represented by two dimensions, one correlated with temporal envelope features and the other weakly correlated with spectral envelope features of the stimuli. Conclusions: Temporal envelope was a dominant cue for timbre perception in CI listeners. Compared to NH listeners, CI listeners showed reduced reliance on both spectral envelope and spectral fine structure cues for timbre perception.

Purpose: To estimate real-environment iPod listening levels for listeners in 4 environments to gain insight into whether average listeners receive dosages exceeding occupational noise exposure guidelines as a result of their listening habits. Method: The earbud outputs of iPods were connected directly into the inputs of a digital recorder to make recordings of listening levels. These recordings were used to estimate listening levels using reference recordings made in a real ear. Recordings were made in 4 environments with a wide range of background noises: (a) a library, (b) a student center, (c) busy streets, and (d) the subway. Results: None of the 64 listeners were estimated to exceed allowable occupational dosages, with a maximum dose of 7.57% based on Occupational Safety and Health Administration (OSHA; 1998) methods and 10.83% based on National Institute for Occupational Safety and Health (NIOSH; 1998) methods. Conclusions: All of the listeners surveyed were exposed to dosages well below OSHA and NIOSH occupational regulations. Although this does not guarantee individual safety, the results do not support the widespread concern regarding the safety of common iPod usage. However, measurements made in this study agree with the finding that iPod output can exceed safe levels and further support recommendations to monitor and limit listening volume and listening duration.

Purpose: The purpose of this study was to investigate musical timbre perception in cochlear-implant (CI) listeners using a multidimensional scaling technique to derive a timbre space. Methods: Sixteen stimuli that synthesized western musical instruments were used (McAdams, Winsberg, Donnadieu, De Soete, & Krimphoff, 1995). Eight CI listeners and 15 normal-hearing (NH) listeners participated. Each listener made judgments of dissimilarity between stimulus pairs. Acoustical analyses that characterized the temporal and spectral characteristics of each stimulus were performed to examine the psychophysical nature of each perceptual dimension. Results: For NH listeners, the timbre space was best represented in three dimensions, one correlated with the temporal envelope (log-attack time) of the stimuli, one correlated with the spectral envelope (spectral centroid), and one correlated with the spectral fine structure (spectral irregularity) of the stimuli. The timbre space from CI listeners, however, was best represented by two dimensions, one correlated with temporal envelope features and the other weakly correlated with spectral envelope features of the stimuli. Conclusions: Temporal envelope was a dominant cue for timbre perception in CI listeners. Compared to NH listeners, CI listeners showed reduced reliance on both spectral envelope and spectral fine structure cues for timbre perception. Key Words: cochlear implant, timbre, music, Cochlear implants (CIs) were originally designed to aid speech recognition for severely hard-of-hearing individuals. Recently implanted CI patients can achieve average sentence recognition scores above 80% correct in quiet (see [...]

Purpose: To estimate real-environment iPod listening levels for listeners in 4 environments to gain insight into whether average listeners receive dosages exceeding occupational noise exposure guidelines as a result of their listening habits. Method: The earbud outputs of iPods were connected directly into the inputs of a digital recorder to make recordings of listening levels. These recordings were used to estimate listening levels using reference recordings made in a real ear. Recordings were made in 4 environments with a wide range of background noises: (a) a library, (b) a student center, (c) busy streets, and (d) the subway. Results: None of the 64 listeners were estimated to exceed allowable occupational dosages, with a maximum dose of 7.57% based on Occupational Safety and Health Administration (OSHA; 1998) methods and 10.83% based on National Institute for Occupational Safety and Health (NIOSH; 1998) methods. Conclusions: All of the listeners surveyed were exposed to dosages well below-OSHA and NIOSH occupational regulations. Although this does not guarantee individual safety, the results do not support the widespread concern regarding the safety of common iPod usage. However, measurements made in this study agree with the finding that iPod output can exceed safe levels and further support recommendations to monitor and limit listening volume and listening duration. KEY WORDS: noise, portable music device, iPod, OSHA, A number of studies have demonstrated that the maximum output levels produced by many portable listening devices, including tapes, CDs, and MP3 players, can exceed Occupational Safety and Health Administration [...]