Visualization of sound field using Optical Wave Microphone coupled with computerized tomography

AbstractThe light diffraction technique, which we call the “Optical Wave Microphone (OWM)” technique, is an effective sensing method to detect the sound and is flexible for practical uses as it involves only a simple optical lens system. This technique is also very useful to detect the sound wave without disturbing the sound field. Moreover, OWM can be used for sound field visualization by computerized tomography (CT) because the ultrasmall modulation by the sound field is integrated along the laser beam path. The characteristics of the coplanar DBD (Dielectric Barrier Discharge) operated in air is investigated. Applied voltage, current and the electrical discharge sound of coplanar DBD are measured, and examined the relationship between the micro discharge and the acoustic properties. We expect that understanding of acoustic properties gives more details of electric discharges. These are the first experiments to verify the feasibility of the OWM-CT method for the visualization of the sound field of DBD discharge.

Download Full-text

Visualization of sound field with uniform phase distribution using laser beam microphone coupled with computerized tomography method

Acoustical Science and Technology ◽

10.1250/ast.29.295 ◽

2008 ◽

Vol 29 (4) ◽

pp. 295-299 ◽

Cited By ~ 15

Author(s):

Tatsuya Sakoda ◽

Yoshito Sonoda

Keyword(s):

Laser Beam ◽

Computerized Tomography ◽

Phase Distribution ◽

Sound Field ◽

Tomography Method

Download Full-text

Investigation of Electric Discharge Sound in Atmospheric Pressure Plasma

Journal of Advanced Oxidation Technologies ◽

10.1515/jaots-2010-0106 ◽

2010 ◽

Vol 13 (1) ◽

Cited By ~ 2

Author(s):

Toshiyuki Nakamiya ◽

Fumiaki Mitsugi ◽

Shota Suyama ◽

Tomoaki Ikegami ◽

Yoshito Sonoda ◽

...

Keyword(s):

Electric Discharge ◽

Sound Field ◽

Atmospheric Pressure Plasma ◽

Dominant Frequency ◽

Medical Diagnostics ◽

Acoustic Properties ◽

Diffraction Effect ◽

Electric Discharges ◽

Optical Wave ◽

Fundamental Relationship

AbstractThe characteristics of the Coplanar DBD (Dielectric Barrier Discharge) operated in air, argon or helium are investigated. Applied voltage, current and the electrical discharge sound of Coplanar DBD discharge are measured, and examined the fundamental relationship between the micro discharge and the acoustic properties. We expect that the understanding of acoustic properties gives more details of electric discharges and also develops new applications in the field of medical diagnostics, environment system, etc. We apply the new method to examine the electric discharge sound using Fraunhofer diffraction effect of visible laser beam. This new system is called the optical wave microphone by us and is very useful for the detection of sound wave without disturbing the sound field. The Fast Fourier Transform (FFT) is applied to discriminate the acoustic sound of the Coplanar DBD discharge and the dominant frequency components.

Download Full-text

Decay of Temporary Threshold Shift in Noise

Journal of Speech and Hearing Research ◽

10.1044/jshr.1602.267 ◽

1973 ◽

Vol 16 (2) ◽

pp. 267-270 ◽

Cited By ~ 5

Author(s):

John H. Mills ◽

Seija A. Talo ◽

Gloria S. Gordon

Keyword(s):

Sound Field ◽

Threshold Shift ◽

Temporary Threshold Shift ◽

Octave Band ◽

Band Noise ◽

Lower Asymptote

Groups of monaural chinchillas trained in behavioral audiometry were exposed in a diffuse sound field to an octave-band noise centered at 4.0 k Hz. The growth of temporary threshold shift (TTS) at 5.7 k Hz from zero to an asymptote (TTS ∞ ) required about 24 hours, and the growth of TTS at 5.7 k Hz from an asymptote to a higher asymptote, about 12–24 hours. TTS ∞ can be described by the equation TTS ∞ = 1.6(SPL-A) where A = 47. These results are consistent with those previously reported in this journal by Carder and Miller and Mills and Talo. Whereas the decay of TTS ∞ to zero required about three days, the decay of TTS ∞ to a lower TTS ∞ required about three to seven days. The decay of TTS ∞ in noise, therefore, appears to require slightly more time than the decay of TTS ∞ in the quiet. However, for a given level of noise, the magnitude of TTS ∞ is the same regardless of whether the TTS asymptote is approached from zero, from a lower asymptote, or from a higher asymptote.

Download Full-text

Modified Earpieces and CROS for High Frequency Hearing Losses

Journal of Speech and Hearing Research ◽

10.1044/jshr.1101.204 ◽

1968 ◽

Vol 11 (1) ◽

pp. 204-218 ◽

Cited By ~ 9

Author(s):

Elizabeth Dodds ◽

Earl Harford

Keyword(s):

Hearing Loss ◽

Hearing Aids ◽

High Frequency ◽

Hearing Aid ◽

Sound Field ◽

Intensity Level ◽

Test Results ◽

High Frequency Hearing Loss ◽

Increased Sensitivity ◽

Difficult Cases

Persons with a high frequency hearing loss are difficult cases for whom to find suitable amplification. We have experienced some success with this problem in our Hearing Clinics using a specially designed earmold with a hearing aid. Thirty-five cases with high frequency hearing losses were selected from our clinical files for analysis of test results using standard, vented, and open earpieces. A statistical analysis of test results revealed that PB scores in sound field, using an average conversational intensity level (70 dB SPL), were enhanced when utilizing any one of the three earmolds. This result was due undoubtedly to increased sensitivity provided by the hearing aid. Only the open earmold used with a CROS hearing aid resulted in a significant improvement in discrimination when compared with the group’s unaided PB score under earphones or when comparing inter-earmold scores. These findings suggest that the inclusion of the open earmold with a CROS aid in the audiologist’s armamentarium should increase his flexibility in selecting hearing aids for persons with a high frequency hearing loss.

Download Full-text