Sound transmission to and within the human ear canal

Hammershøi, Dorte; Møller, Henrik

doi:10.1121/1.415856

Cited by 123 publications

(87 citation statements)

References 12 publications

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“…The ear canal can be modeled as a transmission line (acoustical waveguide) as presented, e.g., in [6] and later discussed, e.g., in [2].…”

Section: Ear Canal Modeling and Estimation Of Pressure At Eardrummentioning

confidence: 99%

Estimating pressure and volume velocity in the ear canal for insert headphones

Hiipakka

2011

2011 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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It is difficult to measure or estimate accurately the pressure or the volume velocity at the eardrums of human subjects. A method that enables us to determine both the pressure and the volume velocity evoked by an insert earphone in the ear canal is developed. The method can be used to accurately estimate pressure frequency response at the eardrum. A pair of headphones with in-ear microphones is modeled as a Norton equivalent electroacoustic volume velocity source. A custom-made new miniature particle velocity sensor is used in the modeling of the velocity source. Measurements made with the particle velocity sensor and those made with miniature microphones show that the presented estimation method is accurate up to 12 kHz. The method can be applied to binaural reproduction as well as to audiological measurements.

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“…The ear canal can be modeled as a transmission line (acoustical waveguide) as presented, e.g., in [6] and later discussed, e.g., in [2].…”

Section: Ear Canal Modeling and Estimation Of Pressure At Eardrummentioning

confidence: 99%

Estimating pressure and volume velocity in the ear canal for insert headphones

Hiipakka

2011

2011 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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“…With proper equalization these measurements can re-create the sound spectrum at the tympanum (Kulkarni and Colburn 1998). The HRTFs measured at the tympanum can be separated into 2 terms: one that varies with direction of incidence, and another term that contains the nondirectional transfer function of the ear canal (e.g., Hammershøi and Møller 1996). The directional part of the HRTF can be measured at a distance of a few millimeters from the entrance of the blocked ear canal.…”

Section: Generation Of the Virtual Auditory Environmentmentioning

confidence: 99%

Spatial Tuning to Virtual Sounds in the Inferior Colliculus of the Guinea Pig

Sterbing

Hartung

Hoffmann

2003

Journal of Neurophysiology

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. How do neurons in the inferior colliculus (IC) encode the spatial location of sound? We have addressed this question using a virtual auditory environment. For this purpose, the individual head-related transfer functions (HRTFs) of 18 guinea pigs were measured under free-field conditions for 122 locations covering the upper hemisphere. From 257 neurons, 94% responded to the short (50-ms) white noise stimulus at 70 dB sound pressure level (SPL). Out of these neurons, 80% were spatially tuned with a receptive field that is smaller than a hemifield (at 70 dB). The remainder responded omnidirectionally or showed fractured receptive fields. The majority of the neurons preferred directions in the contralateral hemisphere. However, preference for front or rear positions and high elevations occurred frequently. For stimulation at 70 dB SPL, the average diameter of the receptive fields, based on half-maximal response, was less than a quarter of the upper hemisphere. Neurons that preferred frontal directions responded weakly or showed no response to posterior directions and vice versa. Hence, front/back discrimination is present at the single-neuron level in the IC. When nonindividual HRTFs were used to create the stimuli, the spatial receptive fields of most neurons became larger, split into several parts, changed position, or the response became omnidirectional. Variation of absolute sound intensity had little effect on the preferred directions of the neurons over a range of 20 to 40 dB above threshold. With increasing intensity, most receptive fields remained constant or expanded. Furthermore, we tested the influence of binaural decorrelation and stimulus bandwidth on spatial tuning. The vast majority of neurons with a low characteristic frequency (Ͻ2.5 kHz) lost spatial tuning under stimulation with binaurally uncorrelated noise, whereas high-frequency units were mostly unaffected. Most neurons that showed spatial tuning under broadband stimulation (white noise and 1 octave wide noise) turned omnidirectional when stimulated with 1/3 octave wide noise. I N T R O D U C T I O NExternal sounds are diffracted and partly shadowed by the head and body and then are further modified as they enter the external ear. Thus spectral modifications, which are specific with respect to the directions of the sound sources relative to the listener's head, are imposed on the incoming sound signals on their way to the eardrums. It is possible to measure these head-related transfer functions (HRTFs) by recording signals in the ear canal after presentation of sounds at different locations (for review, see Blauert 1996). Presenting sounds convolved with the HRTFs through earphones can result in percepts that are indistinguishable from the original external sounds. Thus these virtual acoustic space signals contain all information necessary for localization: interaural information [interaural level difference (ILD) and interaural time difference (ITD)] as well as monaural spectral cues.Because the external ear can be described as a linear time...

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“…As the radiation impedance (Z r ) does not include the part of the sound incidence direction in Eq. (13), we found that the transmission characteristics of the ear canal are not affected by the sound incidence direction [5].…”

Section: Resultsmentioning

confidence: 63%

Transmission characteristics of ear canal of artificial head

Sugiyama

Nishimoto

Machiko

2005

Acoust. Sci. & Tech.

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IntroductionThe head related transfer function (HRTF) expresses how the acoustical characteristics change with the sound source position. HRTF is defined as the ratio of the sound pressure at the eardrum to that of the free field at the center of the head [1].If the HRTF is shown as a function on the effect of the pinna, the ear canal, and the body including head and torso, each effect can be discussed separately. If the pinna of an artificial head is removed and/or if the ear canal is blocked, HRTFs can be divided into three parts corresponding to the pinna, the ear canal and the body [2].In this paper, we discuss the impact of the ear canal and how it changes with the sound incidence direction. Measured values are compared with values calculated for a 2-sphere model in which the head and torso are approximated by spheres.

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Sound transmission to and within the human ear canal

Cited by 123 publications

References 12 publications

Estimating pressure and volume velocity in the ear canal for insert headphones

Estimating pressure and volume velocity in the ear canal for insert headphones

Spatial Tuning to Virtual Sounds in the Inferior Colliculus of the Guinea Pig

Transmission characteristics of ear canal of artificial head

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