Some thoughts on the perception of ultrasonics by man

Abstract

After a short specification of the ultrasonic transmitter device by which the test frequencies of 20,40,60 and 100 kHz could be emitted by means of a transmitter fixed to the forehead of the subject with constant pressure, the mean perception threshold for ultrasonics is described, which had been recorded by using the wide-band noise of the audiometer MA 30. Both curves do not differ considerably so that ultrasonic investigations can be carried out in the presence of working noise without producing wrong measurement results. A comparison of perception between ultrasonic frequencies and audio frequencies in the hearing range showed that ultrasonics produce, independent of the stimulation frequency, the same sensory impression as a sound at a frequency of about 12 or 13 kHz. Applying this method to hard of hearing subjects with noise induced hearing damages and deaf subjects had the following results: 1. Subjects with noise induced hearing damages very early have a raised perception threshold for ultrasonics. There was no correlation between the extent of the auditory threshold (the shift of the threshold) and the perception threshold of ultrasonics. 2. Deaf people almost without exception are not able to perceive ultrasonics. 3. With hard of hearing of the inner ear of different genesis ultrasonic perception is varying. There was no particular raise of the ultrasonic perception threshold with hereditary hard of hearing of the inner ear. 4. On the basis of the results the question is discussed in which section of the auditory system ultrasonic perception occurs. In the opinion of the authors the origin of perception might be in the organ of Corti itself. An unambiguous proof, however, could not be found so far. At present the procedure of investigation does not yet allow an application in practical diagnostics of ear specialists.

Peripheral perception mechanism of ultrasonic hearing

“…According to previous reports, the maximum audible frequency for the human ear is approximately 24 kHz via air conduction (Wegel, 1932), and the frequency range above this is regarded as the ultrasonic range. However, when ultrasound at a frequency of lower than 120 kHz is delivered via bone conduction, it can create an auditory sensation (Gavreau, 1948;Pumphrey, 1950;Dieroff and Ertel, 1975). This phenomenon has been reported for half a century, and has been the focus of numerous reports (Gavreau, 1948;Pumphrey, 1950;Haeff and Knox, 1963;Dieroff and Ertel, 1975).…”

“…According to these previous reports, the reason for such ultrasound being perceptible only by bone conduction may be that it is not transmitted to the cochlea via the middle ear due to poor impedance (Pumphrey, 1950;Corso, 1963). Other reports have also raised the possibility of perceiving an audible sound that is generated by a nonlinear process in bone conduction (Haeff and Knox, 1963;Dieroff and Ertel, 1975). If this mysterious phenomenon depended solely on the impedance of the middle ear or nonlinearity, the perceptual characteristics of bone-conducted ultrasound (BCU) would not be particularly different from those of air-conducted audible sound (ACAS).…”

“…However, when ultrasound at a frequency of lower than 120 kHz is delivered via bone conduction, it can create an auditory sensation (Gavreau, 1948;Pumphrey, 1950;Dieroff and Ertel, 1975). This phenomenon has been reported for half a century, and has been the focus of numerous reports (Gavreau, 1948;Pumphrey, 1950;Haeff and Knox, 1963;Dieroff and Ertel, 1975). According to these previous reports, the reason for such ultrasound being perceptible only by bone conduction may be that it is not transmitted to the cochlea via the middle ear due to poor impedance (Pumphrey, 1950;Corso, 1963).…”

Einfluss einer kurzfristigen Schallbelastung auf das Verhalten transitorisch evozierter otoakustischer Emissionen

“…Zwischen der TTS und dem permanenten Hörschaden wurde bisher noch kein direkter Zusammenhang gefunden [24][25][26], Auch ist die Bedeutung der perstimulatorischen Adaptation als kom plexer Schutzmechanismus gegen Lärmeinwirkung bis her ungenügend berücksichtigt worden [27][28][29][30], obwohl die Adaptation als ein sehr stabiles Phänomen gilt [31 ].…”

“…So konnte experimentell nachgewie sen werden, dass eine Unterbrechung der efferenten Ner venfasern des olivokochleären Bündels und eine nachfol gende Schallbelastung zu signifikant grösseren permanen ten Hörschäden und TTS führt als bei intaktem Fasersy stem [31,32] 3. Die Erholung der TTS ist verlangsamt und unabhän gig von ihrem Ausmass [24][25][26].…”