In This Section
Journal of the AES
2009 July/August - Volume 57 Number 7/8
The utility of loudspeaker driver models is enhanced when a lumped parameter representation is supplemented with the parameters of a surface vibration representation. While the lumped model has a one-dimensional representation of input and output, the surface model considers multiple points on the surface as each contributes to the sound pressures of the receiving point. This article explores how to measure and parameterize the distributed points on the surface of various elements using a measurement grid of about 100 points.
Combining Methods for Multichannel Room Impulse Response Generation and Objective and Subjective Performance Evaluation
There are many methods for deriving multichannel room impulse responses (RIR) when reference RIRs are provided. Previous articles focused on a method for synthesizing the early part of the process, dominated by discrete reflections, and a method for synthesizing the late part of the process, dominated by statistical diffuse reverberation. In order to take advantage of their respective benefits, these two approaches can be combined with a simple windowing technique with a variable transition point. Objective and subjective evaluations confirm the validity of the RIR synthesis methods and the method of combination.
High- and low-order all-pass networks have been used extensively in a wide variety of audio applications, such as reverberators, because they change the phase and temporal structure without changing the frequency content. Each frequency region experiences an independent delay. In this paper the authors explore how these properties can be used to create unusual special effects. The perceived timbre is changed even though the frequency content remains unchanged. By cascading a large number of such filters, a chirplike sound can be created, which can be equalized and mixed with the original. This is yet another form of sound synthesis.
Multichannel Fast-Acting Dynamic Range Compression Hinders Performance by Young, Normal-Hearing Listeners in a Two-Talker Separation Task
Because of the well-known benefits of dynamic range compression, sound engineers routinely use this tool as a normal part of their professional activities. Hearing aid designers also use compression. However, compression can impede perception of independent sound sources in a complex aural environment. When normal young listeners were given the task of recognizing keywords from two simultaneous talkers, their performance worsened when compression was applied to the mixed signal. Even when performance remained unchanged, the cognitive load, as measured using a secondary task, increased significantly. The results indicate that excessive compression can lead to increased listening effort.
Standards and Information Documents
AES Standards Committee News
Web site; timing and synchronization; loudspeaker polar radiation measurements; microphone measurement and characterization; audio connectors; grounding and EMC practices
Digital Television (DTV) audio has been the subject of many misunderstandings over the years, particularly concerning encoding standards, surround sound, and metadata for loudness control. In a workshop at the 125th Convention last year in San Francisco, a panel of experts chaired by Jim Kutzner of PBS chewed over these “DTV myths” and engaged in some selective myth-busting to clear up misconceptions.
126th Convention Report, Munich
126th Convention Exhibitors
127th Convention Preview, New York
127th Convention Exhibit Previews