In This Section
Journal of the AES
2010 October - Volume 58 Number 10
A theory for modeling sound sources as a combination of a source and filter parts is useful in timbre analysis and synthesis. In this model the sound is represented as a sparse sum of sine waves, each of which is characterized by a slowly varying amplitude and frequency. Two methods are considered for deriving the parameters of the model: slow variation (SV) and filter bank (FB). The FB method better follows the global spectral envelope, while the SV method better follows local amplitude–frequency dependencies. Real and synthetic sounds are analyzed in detail.
In the typical stereophonic listening environment, a listener is usually not sitting in the relatively small sweet spot of good localization. This deficiency can be overcome with a system that senses the location of the listener in real time and adaptively adjusts the loudspeaker signals. A theoretical analysis using a binaural model shows that stereophonic localization and image stability can be improved.
While the auditory system can sense vibration to about 20 Hz, tactile sensitivity extends that range to about 0.4 Hz. A proposed method for full-range reproduction includes haptic reproduction. Playback is achieved through headphones and a calibrated motion platform. The absolute magnitude and frequency response of the tactile portion must be considered with the same attention that is devoted to sound in order to produce a compelling experience. Even though the initial evaluation of the system suggested that the haptic portion might not be important, when it was turned off, something was clearly missing. Reproduction lacked presence.
Improving the Response of Loudspeaker Line Arrays by a Staggered Arrangement of High-Frequency Waveguides
Staggering a linear array of waveguides, as compared to a straight topology, offers an additional degree of freedom in optimizing the design for sound reinforcement applications. A comparison of staggered and straight arrangements reveals significant differences. Staggered arrays can have decreased sidelobes and reduced fluctuations in off-axis response. Smaller staggering intervals lead to wider horizontal coverage area. Within expected errors, the experimental data is consistent with simulation results with regard to such parameters as vertical directivity and frequency response smoothness.
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Perceptual models and computational predictions based on metrics are increasingly used to evaluate sound quality. An alternative might be to measure listeners’ brain waves to get a more objective view of their responses to different qualities of sound. Applications of these technologies in hearing aid design, room acoustics, and automotive audio were discussed in papers presented at the AES 38th International Conference.
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