Fundamentals of Binaural Technology
TL;DR: In this paper, the fundamental ideas of the binaural recording technique are discussed and a model is given that describes the sound transmission from a source in a free field, through the external ear to the eardrum.
About: This article is published in Applied Acoustics.The article was published on 1992-01-01 and is currently open access. It has received 428 citations till now. The article focuses on the topics: Binaural recording & Dummy head recording.
Citations
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21 Oct 2001
TL;DR: A public-domain database of high-spatial-resolution head-related transfer functions measured at the UC Davis CIPIC Interface Laboratory and the methods used to collect the data are described.
Abstract: This paper describes a public-domain database of high-spatial-resolution head-related transfer functions measured at the UC Davis CIPIC Interface Laboratory and the methods used to collect the data.. Release 1.0 (see http://interface.cipic.ucdavis.edu) includes head-related impulse responses for 45 subjects at 25 different azimuths and 50 different elevations (1250 directions) at approximately 5/spl deg/ angular increments. In addition, the database contains anthropometric measurements for each subject. Statistics of anthropometric parameters and correlations between anthropometry and some temporal and spectral features of the HRTFs are reported.
1,017 citations
Book•
01 Jan 1994TL;DR: In this article, technology and applications for the rendering of virtual acoustic spaces are reviewed, including applications to computer workstations, communication systems, aeronautics and space, and sonic arts.
Abstract: Technology and applications for the rendering of virtual acoustic spaces are reviewed. Chapter 1 deals with acoustics and psychoacoustics. Chapters 2 and 3 cover cues to spatial hearing and review psychoacoustic literature. Chapter 4 covers signal processing and systems overviews of 3-D sound systems. Chapter 5 covers applications to computer workstations, communication systems, aeronautics and space, and sonic arts. Chapter 6 lists resources. This TM is a reprint of the 1994 book from Academic Press.
960 citations
Journal Article•
TL;DR: In this paper, head-related transfer functions (HRTFs) were measured on 40 human subjects for 97 directions of sound incidence, covering the entire sphere Individual HRTF data for the median, horizontal, and frontal planes are presented in the frequency domain Measurements were made synchronously at both ears, thus making the time representations, that is, the headrelated impulse responses, valid also when interaural time differences are considered.
Abstract: Head-related transfer functions (HRTFs) were measured on 40 human subjects for 97 directions of sound incidence, covering the entire sphere Individual HRTF data for the median, horizontal, and frontal planes are presented in the frequency domain Measurements were made synchronously at both ears, thus making the time representations, that is, the head-related impulse responses (HRIRs), valid also when interaural time differences are considered The measurements were made at the entrance to the blocked ear canal Sound at this point contains full spatial information, and the interindividual variation is lower than at the open ear canal
332 citations
Book•
30 Apr 1998
TL;DR: Thesis (Ph. D.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1997.
Abstract: Thesis (Ph. D.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1997.
239 citations
TL;DR: It is shown that simple geometrical approximations and models of the head and torso explain these low-frequency features and the corresponding elevations cues and the existence of elevation-dependent features at low frequencies.
Abstract: Monaural spectral features due to pinna diffraction are the primary cues for elevation. Because these features appear above 3 kHz where the wavelength becomes comparable to pinna size, it is generally believed that accurate elevation estimation requires wideband sources. However, psychoacoustic tests show that subjects can estimate elevation for low-frequency sources. In the experiments reported, random noise bursts low-pass filtered to 3 kHz were processed with individualized head-related transfer functions (HRTFs), and six subjects were asked to report the elevation angle around four cones of confusion. The accuracy in estimating elevation was degraded when compared to a baseline test with wideband stimuli. The reduction in performance was a function of azimuth and was highest in the median plane. However, when the source was located away from the median plane, subjects were able to estimate elevation, often with surprisingly good accuracy. Analysis of the HRTFs reveals the existence of elevation-dependent features at low frequencies. The physical origin of the low-frequency features is attributed primarily to head diffraction and torso reflections. It is shown that simple geometrical approximations and models of the head and torso explain these low-frequency features and the corresponding elevations cues.
219 citations
References
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TL;DR: The new method combines the advantages of the ray‐tracing process, namely, the relatively slow increase of computation time with the length of the impulse response, with the accuracy inherent to the image‐source model, which is even sufficient to calculate the Fourier transform.
Abstract: A new method for the calculation of room acoustical impulse responses is described, which is based on two well‐known computer algorithms, the ray‐tracing and the image‐source models. With the new method, the procedure of sieving the ‘‘visible’’ image sources out of the enormous quantity of possible sources is carried out by examination of the histories of sound particles. From the obtained list of visible image sources, the impulse response of the enclosure is easily constructed. The new method combines the advantages of the ray‐tracing process, namely, the relatively slow increase of computation time with the length of the impulse response, with the accuracy inherent to the image‐source model, which is even sufficient to calculate the Fourier transform, i.e., the steady‐state transmission function of the room, or to convolve the impulse response with sound signals.
288 citations
TL;DR: With an impulse response technique the transfer functions from the free sound field to the ear‐canal entrance were measured on 20 subjects for sound incidence and the eardrum impedance was computed from this transfer function and completes the poor knowledge of the eARDrum impedance in the frequency range from 2 to 15 kHz.
Abstract: With an impulse response technique the transfer functions from the free sound field to the ear‐canal entrance were measured on 20 subjects for sound incidence from ten directions of the symmetry plane and 20 directions of the horizontal plane. Separate for each direction amplitude and phase of these transfer functions were averaged using a technic, which yields mean values still containing fine structures of single measurements. Additionally the transfer function of the ear canal was measured on three subjects. The eardrum impedance was then computed from this transfer function and completes the poor knowledge of the eardrum impedance in the frequency range from 2 to 15 kHz.
269 citations
TL;DR: The results indicate the types of horizontal and vertical spatial information that are available from sound level cues over various ranges of frequency and, within a small subject population, indicate the nature of intersubject variability.
Abstract: Changes in sound pressures measured in the ear canal are reported for broadband sound sources positioned at various locations about the subject. These location-dependent pressures are one source of acoustical cues for sound localization by human listeners. Sound source locations were tested with horizontal and vertical resolution of 10 degrees. Sound levels were measured with miniature microphones placed inside the two ear canals. Although the measured amplitude spectra varied with the position of the microphone in the ear canal, it is shown that the directional sensitivity at any particular frequency of the broadband stimulus is independent of microphone position anywhere within the ear canal. At any given frequency, the distribution of sound pressures as a function of sound source location formed a characteristic spatial pattern comprising one or two discrete areas from which sound sources produced maximum levels in the ear canal. The locations of these discrete areas varied in horizontal and vertical location according to sound frequency. For example, around 8 kHz, two areas of maximum sensitivity typically were found that were located laterally and were separated from each other vertically, whereas, around 12 kHz, two such areas were found located on the horizontal plane and separated horizontally. The spatial patterns of sound levels were remarkably similar among different subjects, although some frequency scaling was required to accommodate for differences in the subjects' physical sizes. Interaural differences in sound-pressure level (ILDs) at frequencies below about 8 kHz tended to increase monotonically with increasing distance of the sound source from the frontal midline and tended to be relatively constant as a function of vertical source location. At higher frequencies, however, ILDs varied both with the horizontal and with the vertical location of the sound source. At some frequencies, asymmetries between the left and right ears in a given subject resulted in substantial ILDs even for midline sound sources. These results indicate the types of horizontal and vertical spatial information that are available from sound level cues over various ranges of frequency and, within a small subject population, indicate the nature of intersubject variability.
241 citations
TL;DR: The ODEON room acoustics program is intended to be a base for research in objective and subjective room acoustic research, and a useful tool for consultants, in which an initial ray tracing is carried out to determine potential reflection sequences.
186 citations
TL;DR: A series of experiments carried out to further elucidate the role of spectral cues in locating sounds in the median sagittal plane (MSP) revealed a notch in the frequency response curves which migrated toward the lower frequencies as the sound source was moved from above to below the aural axis.
Abstract: A series of experiments was carried out to further elucidate the role of spectral cues in locating sounds in the median sagittal plane (MSP). Broadband noise bursts, generated at ±30°, ±15°, and O° re aural axis, were recorded via microphones placed in the external ear canals of 8 Ss. When these recorded sounds were played back dichotically through headphones, they were perceived as originating from the loudspeakers, not the headphones. In fact, Ss could identify that loudspeaker which originally generated the sound nearly as accurately as they could when listening under free‐field conditions. Analysis of the spectra of these recorded sounds revealed a notch in the frequency response curves which migrated toward the lower frequencies as the sound source was moved from above to below the aural axis. This feature of the spectrum may well be important for accuracy in locating sounds emanating from the frontal segment of the MSP. Four Ss were given additional tests to find out whether they could locate sounds...
182 citations