Audio Playback Research Articles

The Design and Evaluation of an Economically Constructed Anechoic Chamber

This paper reports on a study of the design of an economic anechoic chamber so that a controlled environment would be readily available for acoustic experiments such as 3-D audio playback through a spherical loudspeaker array. It describes measurements performed to evaluate the room's acoustical performance against ISO 3745 and some ITU-R BS.1116-1 recommendations. Two custom omnidirectional sound sources were developed for the mid and high frequency range to perform some of these measurements. The data from these measurements indicate that the room has a noise rating of NR15; the carpeted floor absorbs at least 50% of incident sound energy above 400 Hz, and the room exhibits free-field conditions in all directions tested up to 2 m from the centre of the room between 400 Hz and 20 kHz. Hence, this paper presents a model of how an economic anechoic chamber could be designed for high-resolution spatial audio applications (such as audio reproduction using high order ambisonics), and how such a room's acoustic performance can be assessed.

Podcasting by synchronising PowerPoint and voice: What are the pedagogical benefits?

The purpose of this study was to investigate the efficacy of audio–visual synchrony in podcasting and its possible pedagogical benefits. ‘Synchrony’ in this study refers to the simultaneous playback of audio and video data streams, so that the transitions between presentation slides occur at “lecturer chosen” points in the audio commentary. Manufacturers of lecture recording software (e.g. ProfCast) would have us believe that the synchrony of image and audio should improve the learning experience. We have yet to see in the literature any empirical evidence to support this hypothesis. In our study, 90 participants in two groups undertook two electronic lectures (e-lectures) on two separate topics, the subject matter of neither was familiar to them beforehand. Each group experienced one “synchronous” presentation (e-lecture) of one of the topics, and one “separate” presentation (i.e. PowerPoint and audio files separately presented) of the other topic. Each group therefore experienced both “synchronous” and “separate” delivery and they were then given an MCQ test that assessed five levels of Bloom’s taxonomy. Results show no differences in innate ability between the two groups but the evidence supported our primary hypothesis in that statistically significantly higher test scores were seen when participants viewed a synchronous e-lecture; these scores were accounted for by subjects’ performance at three of the five levels of Bloom’s taxonomy. Qualitative ‘attitude’ survey results also displayed participant preference towards the synchronous over the asynchronous mode of delivery, and in spite of general acceptance of the proposed benefits of electronic proceedings, a majority preference towards traditional rather than electronic lectures. Despite this conservatism, this paper explores in more detail the potential benefits of podcasting via synchronous PowerPoint and voice.

Audio enhancement of biomechanical impact data.

Analysis and interpretation of impact data from a force transducer or accelerometer can be augmented and enhanced using audio playback. Trends and differences which may be difficult to identify using data imagery can be elucidated and reinforced by converting digital data from a force plate to an audio signal, which can then be played through a high‐quality speaker system. The audio stream can be processed using standard acoustical methods such as tempo and pitch shifting, which can emphasize frequencies and tone bursts for improved signal characterization. We apply audio enhancement to data from two separate biomechanical studies: (1) a drop landing experiment for the investigation of gender differences in impact upon landing and (2) an experiment for the investigation of impact differences between cleated and noncleated shoes on artificial turf. The continuous wavelet transform (CWT) is used to process data from a force plate in both studies. Results are compared using the semblance analysis approach described by Cooper and Cowan [“Comparing time series using wavelet‐based semblance analysis,” Computers Geosciences 34, 95–102 (2008)]. Interpretation of results is enhanced using speaker‐driven audio output synthesized from the CWT and semblance analysis.

Audio cassette emulator with cryptographic media distribution control

A device of the same general physical size and shape as a standard audio cassette tape, but which accepts digital information from any of a variety of sources—including for example: Internet transmission, a digital computer, or memory cards (especially digital memory cards)—and plays this digital information through any, for example, standard audio tape cassette player. The device operates by converting the digital representation of the sound into magnetic signals which are presented to the read/write head of the cassette player equipment. The device allows the user of the cassette player to regulate the audio playback using conventional equipment controls such as: START, STOP, REWIND, FAST REWIND, FORWARD, FAST FORWARD, etc. The device has the same general physical dimensions of a standard audio cassette; at least one digital processor; and a slot into which electronic media such as, for example, memory cards, smart cards having a processor and a memory embodied thereon and other memory media may be inserted. Numerous sensors detect changes in at least one of the tape equipment mechanisms in the audio cassette emulator. Various cryptographic techniques are described for protecting the unauthorized distribution of audio information.

Process and apparatus for selecting or designing products having content-free sound outputs

A process and apparatus for selecting or designing a product, such as a muffler, having a complex, content-free sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject ( 21 ) while the subject listens to an initial content-free sound output, repeating the sensing step for a new content-free sound output, comparing the physiological responses, and selecting the sound output for use in selecting or designing the product which output produces the physiological response that is the least stressful or most pleasing to the subject. The apparatus includes an audio playback device ( 15 ), a sound recording ( 16 ) of the initial sound, a sound recording ( 16 ) of the new sound, and physiological monitoring apparatus ( 17 ) suitable for attachment to and monitoring of the physiological responses of the test subject ( 21 ) to the playback of the sound recordings.

Stereo audio headset interface and method that is compatible with mono headsets

A stereo headset interface that is compatible with mono for an audio playback device. A load in series between an audio output from a stereo headset driver and a ground of a mono headset plug prevents the audio output from being grounded when a mono headset plug is inserted into the stereo headset jack of the playback device. A second load in series between a second audio output and the mono headset plug balances the first and second audio outputs from the stereo headset driver.

Multimodal Trajectory Playback for Teaching Shape Information and Trajectories to Visually Impaired Computer Users

There are difficulties in presenting nontextual or dynamic information to blind or visually impaired users through computers. This article examines the potential of haptic and auditory trajectory playback as a method of teaching shapes and gestures to visually impaired people. Two studies are described which test the success of teaching simple shapes. The first study examines haptic trajectory playback alone, played through a force-feedback device, and compares performance of visually impaired users with sighted users. It demonstrates that the task is significantly harder for visually impaired users. The second study builds on these results, combining force-feedback with audio to teach visually impaired users to recreate shapes. The results suggest that users performed significantly better when presented with multimodal haptic and audio playback of the shape, rather than haptic only. Finally, an initial test of these ideas in an application context is described, with sighted participants describing drawings to visually impaired participants through touch and sound. This study demonstrates in what situations trajectory playback can prove a useful role in a collaborative setting.

Active playback of acoustic quadraphonic sound events

The reproduction in a given confined space - such as a cinema hall or a smaller room - of a sound event previously recorded in a completely different acoustical environment is an interesting and still open acoustical problem. A new method for hi-fi audio playback based on the general solution of the acoustic inverse problem is here pourposed. A feed-forward control based on overdetermination of conditions at active contours - i.e. loudspeakers - in order to obtain an optimal stable solution via least square approach is here proposed. This is easily possible even for complex configurations thanks to acoustic quadraphony, the application of sound intensimetry to audio technology developed in the last years within the IST-2-511316-IP European project denominated IP-RACINE. After a short explanation of the model theory, the experimental application to the simplest case of 1-D confined field is presented and some obtained results are shown.

Introducing Computational Fluid Dynamics Simulation into Olfactory Display

An olfactory display is a device that delivers various odors to the user's nose. It can be used to add special effects to movies and games by releasing odors relevant to the scenes shown on the screen. In order to provide high-presence olfactory stimuli to the users, the display must be able to generate realistic odors with appropriate concentrations in a timely manner together with visual and audio playback. In this paper, we propose to use computational fluid dynamics (CFD) simulations in conjunction with an olfactory display. Odor molecules released from their source are transported mainly by turbulent flow, and their behavior can be extremely complicated even in a simple indoor environment. In the proposed system, a CFD solver is employed to calculate the airflow field and the odor dispersal in the given environment. An odor blender is used to generate the odor with the concentration determined from the calculated odor distribution. Experimental results on presenting odor stimuli synchronously with movie clips show the effectiveness of the proposed system. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 65–72, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21087

Method and device for generating information relating to the relative position of a set of at least three acoustic transducers

The invention relates to a method and device for generating data about the mutual position of at least three acoustic transducers. The aim of the invention is to make it possible to continuously measure and calculate the mutual position of at least three acoustic transducers, particularly the rotation and the position of a human head wearing headphones within a room without using any additional transmitter element on the head, headphone, or body of the listener, during audio playback. This aim is achieved by connecting the acoustic transducers to a digitally operated system which comprises an output path emitting audio signals to first and second acoustic transducers, an input path receiving audio signals from the third acoustic transducer, an audio signal source that is connected to the output path, an ultrasound generator that is connected to the output path, and an information generator which indicates a position and is connected to the input path.

Delivery and transmission of dolby digital AC-3 over television broadcast

Methods and apparatus for broadcasting high quality audio “studio direct” with the same digital information employed in the studio by the video producer with AC-3 digital audio signals for broadcast to integrated receiver decoders (IRD). The methods and apparatus permit proper handling of AC-3 data by switching signals to encoders in response to detection of the encoded signals representing compression of the data. Control over individual data bits such as copyright bits is maintained by determining the bit status, comparing it to a preferred status, changing the status if it does not comply with the preferred status, and reevaluating cyclical redundancy check value in each data packet to avoid disruption in the data transmission. In addition, the system includes an uplink device which automatically checks, logs and reports errors in Dolby Digital AC-3 signals by a monitor which employs a processor, a digital audio card and an SMPTE timecode reader. As an option, an ethernet interface may be provided to permit AC-3 transmission to expedite storage and transmission of the audio data by media such as compact disks. The monitor employs a state machine that finds AC-3 packets, locks into the packets and detects discontinuities or loss of signal. The monitor then computes and checks the cyclical redundancy check value of the AC-3 packet found. In addition, the system enables the device to play AC-3 signals such as Dolby Digital out in sync with video signals, regardless of the storage media for the files. A sound card having an input for receiving house reference AES clock pulses enables the AES clock of the playback signal to be locked to the frequency of a production house master as a time code reader or an editor's contact closure match video and audio signals playback.

薬袋のユニバーサルデザイン

A medication envelope functions not only as a drug container but also as a means of providing basic information on the usage and dosage of a drug. We made a prototype medication envelope based on Universal Design (UD) with which administration instructions can be obtained through the senses of sight, hearing and touch. In addition to conventional printed information, the UD medication envelope is equipped with an audio playback device to provide prerecorded spoken instructions on administration. It also has Braille labels so that administration instructions may be checked using the sense of touch.We performed a questionnaire survey of the usefulness of the UD medication envelope after it had been used by visually impaired patients, elderly patients as well as the families of patients, caregivers, nurses, and other individuals assisting patients in taking their drugs in the home health care setting. The results showed that the use of the UD medication envelope enabled the majority of patients to understand administration instructions better, which reduced mistakes in administration. They suggest that the UD medication envelope would help ensure that patients take drugs properly, thereby strengthening safety management, and would be useful in today's society in which there are large numbers or elderly and other types of patient having special needs with regard to understanding administration instructions.

A high-quality digital audio delivery bluetooth platform

The recent growth of home networking applications has raised the requirement for cable-free audio streaming. In this work, the "BlueDAT" digital audio platform is presented, which employs the Bluetooth wireless technology for real-time, CD-like quality, stereo reproduction. It is shown that, despite the strict throughput limitations imposed by the Bluetooth protocol, the BlueDAT application setup can efficiently accommodate cable-free, high-quality audio streaming and playback over one or two receivers for home environments, through the employment of a set of novel mechanisms for the automatic adaptation of both the transmission rate and the audio coding bitrate

Audio recording playback device

A desktop sound producing device for playing audio recordings from pre-recorded media having a plurality of individual selections recorded thereon. The device has a pyramid shaped housing having four side walls extending upward from a bottom wall to an apex forming a cavity therein. A playback mechanism is positioned within the cavity, and includes a means for storing pre-recorded media, and a processing means capable of providing an audio output signal from the pre-recorded median and amplifying the audio output signal for reproduction of the pre-recorded media through a speaker. The processing means can include an optical scanning system for reading pre-recorded media located on a compact disk. A control panel extends outwardly from one of the walls and includes a plurality of depressable keys electrically coupled to the processing means, wherein at least one of the keys is available for playing a single selection from the pre-recorded media. The control panel further includes and at least one said key coupled to a memory means for replaying a selected selection from the pre-recorded media.

Differential audio amplification system

A universal host-powered multimedia speaker system derives its power from a host multimedia computer system chassis, rather than from a conventional dedicated speaker system power supply. The speaker system includes a pair of amplifiers with differential connections for receiving the audio signal and with differential output connections to the speaker to provide it with differential amplification. Differential input amplification amplifies the difference between the signals applied to the amplifiers and thereby rejects the common-mode noise, which including ground circuit electrical noise. Differential output amplification refers to a pair of amplifiers that generate output signals that are 180 degrees out of phase with each other. The differential output amplification provides rejection of power supply electrical noise components. This differential input/differential output host computer-powered speaker system provides low noise, high quality audio playback for multimedia speaker systems deriving power from the host multi-media computer system.

Maintaining motivation using audio review

Rates of initial health behavior change have not consistently translated into similar rates of behavioral maintenance. Of those who achieve short‐term change, most successfully treated individuals revert back to their old high‐risk behaviors soon after treatment. While motivation for change remains a salient issue throughout the behavior change process, maintenance interventions have neglected to focus on the variability of motivation directly. This article proposes that an audio playback procedure that captures motivational decision‐making themes at their highest, most emotionally laden point and replays that material at later dates, may be an effective way to maintain motivation. Highlighted is the role of motivation in maintaining behavior change, the previous literature on audio and video feedback, and the roles of memory systems, cognitive dysfunction, recall bias, cognitive dissonance, change talk, emotional reprocessing and contextual learning on motivation. Special attention will be paid to addictive disorders because of the literature base in this area.

Audio cassette emulator

A device of the same general physical size and shape as a standard audio cassette tape, but which accepts digital information from any of a variety of sources—including for example: Internet transmission, a digital computer, or memory cards (especially digital memory cards)—and plays this digital information through any, for example, standard audio tape cassette player. The device operates by converting the digital representation of the sound into magnetic signals which are presented to the read/write head of the cassette player equipment. The device allows the user of the cassette player to regulate the audio playback using conventional equipment controls such as: START, STOP, REWIND, FAST REWIND, FORWARD, FAST FORWARD, etc. In one exemplary implementation, the device has the same general physical dimensions of a standard audio cassette; at least one digital processor; and a slot into which electronic media such as, for example, memory cards, smart cards having a processor and a memory embodied thereon and other memory media may be inserted. Converter circuitry converts data stored in digital memory to an analog signal which is magnetically coupled to the read head of the equipment. Numerous sensors detect changes in at least one of the tape equipment mechanisms in the audio cassette emulator.

Method and apparatus for providing multimedia playback

During a fast forward search of a multimedia presentation, the audio portion of the multimedia presentation is pitch-adjusted and played back in order to assist the user in determining where within the multimedia presentation the playback currently is located. In another embodiment, the audio playback portion of the multimedia presentation can be buffered such that only intermittent portions of the audio are played back in such a manner that is audible to an end user in determining where in the multimedia presentation the playback routine is located. Another embodiment accommodates a multimedia presentation being reversed will have its audio portion buffered and played back in forward in order to assist the user in determining where in the multimedia presentation the rewind currently is. In addition, an individual word detect can be performed during the rewind whereby each word is individually detected and played forward after its detection.

Robustness of spatial average equalization: A statistical reverberation model approach

Traditionally, multiple listener room equalization is performed to improve sound quality at all listeners, during audio playback, in a multiple listener environment (e.g., movie theaters, automobiles, etc.). A typical way of doing multiple listener equalization is through spatial averaging, where the room responses are averaged spatially between positions and an inverse equalization filter is found from the spatially averaged result. However, the equalization performance, will be affected if there is a mismatch between the position of the microphones (which are used for measuring the room responses for designing the equalization filter) and the actual center of listener head position (during playback). In this paper, we will present results on the effects of microphone-listener mismatch on spatial average equalization performance. The results indicate that, for the analyzed rectangular configuration, the region of effective equalization depends on (i) the distance of a listener from the source, (ii) the amount of mismatch between the responses, and (iii) the frequency of the audio signal. We also present some convergence analysis to interpret the results.

A scalable spherical microphone array for spatial sound capture

With recent popular consumer acceptance of surround-sound audio, there is the need to develop new technologies that will allow for more accurate sound-field recording commensurate with or exceeding current multichannel audio playback systems. Real-world playback systems can have widely varying geometries and number of channels due to space and aesthetic requirements. Thus, there is a need to have a general recording scheme that allows for computationally simple modifications of the signals to optimize the playback for any geometry and number of playback speakers. One would also like to have a recording system that is scalable for future advances in spatial audio playback technology. A spherical microphone array has been proposed as a solution to these requirements. A spherical array has the desired property of enabling a beam pattern that is steering direction invariant with a relatively simple beamformer structure. The spherical array topology enables scalability and an elegant and mathematically straightforward beamformer design for efficient sampling and processing of the acoustic field. This talk will describe how the spherical array beamformer decomposes the sound field into compact multichannel representations that allow computationally efficient transformations to uniquely tailor the playback signals to any specific playback geometry.