In This Section
Journal of the AES
2014 June - Volume 62 Number 6
Multimodal Information Management: Evaluation of Auditory and Haptic Cues for NextGen Communication Displays
Auditory communication displays within the Next Generation Air Transport System (currently under development in the United States) will likely require an improvements in the user interface for selecting amongst multiple incoming messages. Interface design can impact both user performance and preference. Two design factors were evaluated: physical pressure-sensitive switches versus flatpanel "virtual switches," and auditory feedback from switch contact. Performance with stimuli using physical switches was 1.2 s faster than virtual switches (2.0 s vs. 3.2 s); auditory feedback provided a 0.6 s performance advantage (2.3 s vs. 2.9 s). The subjective results show a significant preference and superior performance for physical pressure-sensitive switches having audio feedback, compared to touch-panel virtual switches. The correlation between objective measures of performance and subjective ratings of preference and performance was shown to be high. Overall, the results indicate that any replacement of physical controls by virtual touch screens must be considered carefully, and should include audio feedback.
There is extensive research on listening-room compensation algorithms to remove the unwanted degradations of speech quality. Objective measures for quality assessment are required in order to evaluate such algorithms. They exist in two classes: reverberation-cancellation algorithms that equalize the room impulse response of the acoustic channel, and reverberation-suppression algorithms that remove the reverberant part of the speech signal by calculating the spectral weight for time-frequency coefficients. This paper focuses on evaluating the former. Algorithms are analyzed regarding their capability to assess reverberation, coloration, spectral distortion, perceived distance, and overall quality of the signals. An evaluation of the sound quality of the dereverberated signals is derived from subjective listening tests and then compared to objective measures.
Injecting auxiliary data into a digitized audio stream has been used in watermarking technology that is intended to create copy protection and rights tracking. This application requires robustness and defense against attacks. There are however nonsecure applications that use auxiliary data to enrich the program content, and bit rate is far more important than robustness. The proposed application, using uncompressed PCM audio signals, applies the Quantization Index Modulation technique on the (Integer) Modified Discrete Cosine Transform (MDCT) coefficients of the signal. To achieve inaudibility of the injected information, a psychoacoustic model is used at the embedding stage to exploit the properties of the human auditory system.
In order to avoid the requirement of D-to-A converters when connecting a digital signal to a loudspeaker, researchers have examined numerous types of direct digital-to-sound transducers. This investigation considers an array of transducers fed directly by amplified streams that were obtained from a thermometer unary encoding scheme with a fixed or randomized bit-to-transducer assignment. Even though this research was limited by simulation assumptions and artificially devised transducer dimension, it considers the importance of using real sources rather than idealized point sources. The transducer types, sampling rate, and bit-to-transducer assignment influence the resulting acoustic field. Randomized bit assignment produced a significant reduction in distortion.
Standards and Information Documents
AES Standards Committee News
MADI digital audio interface; XLR polarity; audio applications of networks; loudspeaker modeling and measurement; microphone measurement and characterization; measurement and equalization of sound systems in rooms
50th Conference Report, Murfreesboro
55th Conference Preview, Helsinki
55th Conference Preliminary Program
Acoustic enhancement systems enable a space to sound different without substantially modifying the physical structure or internal acoustic treatment. Ben Kok explained the principles in a recent tutorial, along with discussion of practical issues in a subsequent workshop.
Spaces for live performances are part of the art, enriching timbres, embellishing direction and space, and enveloping the audience. These spaces are all different from each other, but designed to meet certain acoustical criteria related to the kinds of performances for which they are intended: opera, orchestral classics of different periods, and so on. Creating a strongly reflective, diffuse, sound field that conveys the unamplified sounds from live performers to the farthest seats in concert halls without corrupting the temporal details in the performance is a fine balancing act. This is the domain of traditional acoustics. This is Sabine’s “place.” But things change.
57th Conference, Hollywood, Call for Papers