AES Journal

Journal of the AES

2005 July/August - Volume 53 Number 7/8


High-Efficiency Low-Bl Loudspeakers (PDF-342KB)  
Ronald M. Aarts    579
As a critical design parameter of loudspeakers, especially at low frequencies, the force factor (Bl) determines the efficiency, impedance, sound level, temporal response, weight, and cost. High-Bl drivers have good efficiency but require large magnet systems. An alternative approach, which yields much lower cost and weight while preserving efficiency, uses low-Bl drivers. Prototype drivers with moving magnets and stationary coils were evaluated in a limited frequency range where efficiency is highest. This approach is suited to small portable loudspeakers.  

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Discrimination of Group Delay in Clicklike Signals Presented via Headphones and Loudspeakers (PDF-478KB)  
Sheila Flanagan, Brian C. J. Moore, and Michael A. Stone    593
The threshold for detecting a frequency-dependent group delay in a clicklike sound was found to be independent of the center frequency of the delay (1-4 kHz) and was about 2 ms for presentation via headphones, or via loudspeakers in a nonreverberant room, for both binaural and monaural listening. In a reverberant room, thresholds increased, especially at low frequencies. These results suggest that the nonlinear phase response of loudspeakers is unlikely to have any audible effect in typical rooms.  

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A Simple Hybrid Approach to the Time-Scale Modification of Speech (PDF-280KB)  
Don Knox, Nicholas Bailey, and Iain Stewart    612
Time-domain methods for stretching speech usually produce stuttering and roughness artifacts from mismatches at signal segment boundaries, especially with time-stretch ratios greater than 1.3. By combining time-domain and analysis-synthesis methods, a simple hybrid approach greatly reduced such artifacts at ratios greater than 1.6. Formal listening tests demonstrate an improvement in speech quality without incurring the complexity burden of full analysis-synthesis methods. The hybrid algorithm counters spectral mismatch and transient repetition.  

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Directivity of Artificial and Human Speech (PDF-390KB)  
Teemu Halkorsaari, Markus Vaalgamaa, and Matti Karjalainen    620
Having an artificial mouth with the same radiating characteristics of real speakers provides a useful working tool for telecommunications research. Responses to three mouth simulators were compared to that of a group of test subjects in order to evaluate their similarity. More than 10 dB of difference was discovered in the two cases. The main contributors to the human radiating characteristics are mouth aperture size and effects of the upper body.  

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Comments on "Low-DC-Resistance, Low-Frequency Loudspeaker Enclosures"  
Alex de Koster (PDF-78KB)    632
Author's Reply  
Carlo Zuccatti    632
Correction to "Low-DC-Resistance, Low-Frequency Loudspeaker Enclosures"  
Carlo Zuccatti (PDF-78KB)    632
AES Standards Committee News (PDF-101KB)    633
High-resolution multichannel digital interface (HRMAI); digital measurements; digital interfacing; file transfer; transfer technologies; microphones; listening tests  
118th Convention Report, Barcelona (PDF-2.4MB)    642
   Exhibitors (PDF-300KB)    658
   Program (PDF-650KB)    661
119th Convention Preview, New York (PDF-630KB)    714
   Exhibit Previews (PDF-1.3MB)    716
High-Density Optical-Disk Formats (PDF-515KB)    749
High-Resolution Audio in an Age of Universal Playback (PDF-102KB)    754
Reviews of Acoustical Patents (PDF-362KB)    636
News of the Sections (PDF-252KB)    756
Sound Track (PDF-86KB)    762
Upcoming Meetings (PDF-97KB)    763
Available Literature (PDF-97KB)    763
Membership Information (PDF-200KB)    765
Advertiser Internet Directory (PDF-209KB)    767
In Memoriam (PDF-124KB)    775
Sections Contacts Directory (PDF-122KB)    777
AES Conventions and Conferences (PDF-112KB)    784
Order Form for AES 118th Convention Papers (PDF-101KB)    
Cover & Sustaining Members List (PDF-66KB)    
AES Officers, Committees, Offices & Journal Staff (PDF-117KB)    
AES - Audio Engineering Society