Henrik Møller

Bio: Henrik Møller is an academic researcher from Aalborg University. The author has contributed to research in topics: Binaural recording & Loudness. The author has an hindex of 28, co-authored 172 publications receiving 3731 citations.

Fundamentals of binaural technology

Abstract: This article reviews the fundamental ideas of the binaural recording technique. A model is given that describes the sound transmission from a source in a free field, through the external ear to the eardrum. It is shown that sound pressures recorded at any point in the ear canals—possibly even a few millimeters outside and even with a blocked ear canal—can be used for binaural recordings, since they include the full spatial information given to the ear. The sound transmission from a headphone is also described. It is shown how the correct total transmission in a binaural system can be guaranteed by means of an electronic equalizing filter between the recording head and the headphone. The advantage of an open headphone is stated. It is shown that a certain degree of loudspeaker compatibility can be achieved, if the equalizer is divided into a recording side and a playback side. A method for true reproduction of binaural signals through loudspeakers is also described. A number of topical and prospected applications of binaural technology are mentioned. Some of these utilize computer synthesis of binaural signals, a technique which is also described.

Head-Related Transfer Functions of Human Subjects

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

Binaural Technique: Do We Need Individual Recordings?

Abstract: The localization performance was studied when subjects listened 1) to a real sound field and 2) to binaural recordings of the same sound field, made a) in their own ears and b) in the ears of other subjects. The binaural recordings were made at the blocked ear canal entrance, and the reproduction was carried out with individually equalized headphones. Eight subjects participated in the experiments, which took place in a standard listening room. Each stimulus (female speech) was emitted from one of 19 loudspeakers, and the subjects were to indicate the perceived sound source. When compared to real life, the localization performance was preserved with individual recordings. Nonindividual recordings resulted in an increased number of errors for the sound sources in the median plane, where movements were seen not only to nearby directions, but also to directions further away, such as confusion between sound sources in front and behind. The number of distance errors increased only slightly with nonindividual recordings. Earlier suggestions that individuals might localize better with recordings from other individuals found no support.

Low-frequency noise from large wind turbines.

Abstract: As wind turbines get larger, worries have emerged that the turbine noise would move down in frequency and that the low-frequency noise would cause annoyance for the neighbors. The noise emission from 48 wind turbines with nominal electric power up to 3.6 MW is analyzed and discussed. The relative amount of low-frequency noise is higher for large turbines (2.3–3.6 MW) than for small turbines (≤ 2 MW), and the difference is statistically significant. The difference can also be expressed as a downward shift of the spectrum of approximately one-third of an octave. A further shift of similar size is suggested for future turbines in the 10-MW range. Due to the air absorption, the higher low-frequency content becomes even more pronounced, when sound pressure levels in relevant neighbor distances are considered. Even when A-weighted levels are considered, a substantial part of the noise is at low frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors.

The CIPIC HRTF database

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.

3-D sound for virtual reality and multimedia

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.

The arrangement of the three cone classes in the living human eye

Abstract: Human colour vision depends on three classes of receptor, the short- (S), medium- (M), and long- (L) wavelength-sensitive cones. These cone classes are interleaved in a single mosaic so that, at each point in the retina, only a single class of cone samples the retinal image. As a consequence, observers with normal trichromatic colour vision are necessarily colour blind on a local spatial scale1. The limits this places on vision depend on the relative numbers and arrangement of cones. Although the topography of human S cones is known2,3, the human L- and M-cone submosaics have resisted analysis. Adaptive optics, a technique used to overcome blur in ground-based telescopes4, can also overcome blur in the eye, allowing the sharpest images ever taken of the living retina5. Here we combine adaptive optics and retinal densitometry6 to obtain what are, to our knowledge, the first images of the arrangement of S, M and L cones in the living human eye. The proportion of L to M cones is strikingly different in two male subjects, each of whom has normal colour vision. The mosaics of both subjects have large patches in which either M or L cones are missing. This arrangement reduces the eye's ability to recover colour variations of high spatial frequency in the environment but may improve the recovery of luminance variations of high spatial frequency.

Fundamentals of binaural technology

Abstract: This article reviews the fundamental ideas of the binaural recording technique. A model is given that describes the sound transmission from a source in a free field, through the external ear to the eardrum. It is shown that sound pressures recorded at any point in the ear canals—possibly even a few millimeters outside and even with a blocked ear canal—can be used for binaural recordings, since they include the full spatial information given to the ear. The sound transmission from a headphone is also described. It is shown how the correct total transmission in a binaural system can be guaranteed by means of an electronic equalizing filter between the recording head and the headphone. The advantage of an open headphone is stated. It is shown that a certain degree of loudspeaker compatibility can be achieved, if the equalizer is divided into a recording side and a playback side. A method for true reproduction of binaural signals through loudspeakers is also described. A number of topical and prospected applications of binaural technology are mentioned. Some of these utilize computer synthesis of binaural signals, a technique which is also described.