The harp seal, Pagophilus groenlandicus (Erxleben, 1777). X. The air audiogram

1971 ◽  
Vol 49 (3) ◽  
pp. 385-390 ◽  
Author(s):  
J. M. Terhune ◽  
K. Ronald
Keyword(s):  
Middle Ear ◽  
Acoustic Impedance ◽  
Pure Tone ◽  
Free Field ◽  
External Auditory Meatus ◽  
Harp Seal ◽  
Impedance Mismatch ◽  
Pagophilus Groenlandicus

A free-field air audiogram from 1 to 32 kHz was obtained for a Pagophilus groenlandicus trained to respond to pure tone signals. The lowest threshold was at 4 kHz at a level of 29 db//0.0002 dynes/cm2. The air audiogram was generally flat. The critical ratios at 2 and 4 kHz were 10%. The lumen of the external auditory meatus is probably acoustically blocked. The outer and (or) middle ear structures and their acoustic impedance mismatch with the air are believed responsible for the comparatively irregular and slightly insensitive hearing of the seal in air.

The harp seal, Pagophilus groenlandicus (Erxleben, 1777). III. The underwater audiogram

1972 ◽  
Vol 50 (5) ◽  
pp. 565-569 ◽  
Author(s):  
J. M. Terhune ◽  
K. Ronald
Keyword(s):  
Ambient Noise ◽  
Free Field ◽  
Phoca Vitulina ◽  
Harp Seal ◽  
Pagophilus Groenlandicus ◽  
Increased Sensitivity

A free-field underwater audiogram from 0.76 to 100 kHz was obtained for Pagophilus groenlandicus. Areas of increased sensitivity occurred at 2 and 22.9 kHz. The lowest threshold was −32.9 db/μbar at 15.0 kHz. Above 64 kHz the threshold increases at a rate of 40 db/octave. The audiogram was similar to that of the Phoca vitulina. The effects of ambient noise on the audiogram are discussed.

Acoustic Impedance Measurements in Cleft-Palate Children

1975 ◽  
Vol 40 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Fred H. Bess ◽  
H. Donell Lewis ◽  
David J. Cieliczka
Keyword(s):  
Hearing Loss ◽  
Cleft Palate ◽  
Middle Ear ◽  
Acoustic Impedance ◽  
Pure Tone ◽  
Cleft Lip ◽  
Impedance Measurements ◽  
High Incidence ◽  
Middle Ear Disease

Clinical acoustic impedance findings in a group of 40 children with cleft lip or palate and a group of 20 noncleft children are presented. The cleft subjects exhibited a high incidence of hearing loss and aural pathology. The data suggest that impedance measurements lend pertinent supportive information to routine pure-tone audiometric testing in the detection and management of middle-ear disease in the cleft-palate population.

scholarly journals Equal-loudness levels measured with the method of constant stimuli Equal-loudness level contours for pure tone under free-field listening conditions (II).

1997 ◽  
Vol 18 (6) ◽  
pp. 337-340 ◽  
Author(s):  
Hisashi Takeshima ◽  
Yôiti Suzuki ◽  
Masazumi Kumagai ◽  
Toshio Sone ◽  
Takeshi Fujimori ◽  
...  
Keyword(s):  
Pure Tone ◽  
Free Field ◽  
Loudness Level ◽  
Method Of Constant Stimuli

Air Conduction Thresholds and Secretory Otitis Media: A Conventional and Extra-High Frequency Audiometric Comparison

1989 ◽  
Vol 98 (10) ◽  
pp. 767-771 ◽  
Author(s):  
Iain W. S. Mair ◽  
Oddbjørn Fjermedal ◽  
Einar Laukli
Keyword(s):  
Otitis Media ◽  
Middle Ear ◽  
High Frequency ◽  
Pure Tone ◽  
Low Frequency ◽  
Secretory Otitis Media ◽  
Middle Ear Fluid ◽  
Ventilation Tubes ◽  
Air Conduction

A comparison has been made of air conduction threshold changes up to 1 year after myringotomy, aspiration of middle ear fluid, and insertion of ventilation tubes in ten patients with bilateral and 12 with unilateral secretory otitis media (SOM). Pure tone air conduction thresholds have been analyzed in three frequency groups: Low frequency (LF; 0.25, 0.5, and 1 kHz), high frequency (HF; 2,4, and 8 kHz), and extra-high frequency (EHF; 10, 12, 14, and 16 kHz). In the LF and HF ranges, significant improvement came during the first 24 hours after intubation, while in the EHF range, threshold lowering occurred gradually over the following 2 months. Possible explanations for these findings are discussed.

scholarly journals Estimation of harp seal (Pagophilus groenlandicus) pup production in the North Atlantic completed: results from surveys in the Greenland Sea in 2002

2006 ◽  
Vol 63 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Tore Haug ◽  
Garry B. Stenson ◽  
Peter J. Corkeron ◽  
Kjell T. Nilssen
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Temporal Distribution ◽  
Harp Seal ◽  
Greenland Sea ◽  
The North ◽  
Pagophilus Groenlandicus ◽  
Pack Ice ◽  
Photographic Survey ◽  
Strip Transect

Abstract From 14 March to 6 April 2002 aerial surveys were carried out in the Greenland Sea pack ice (referred to as the “West Ice”), to assess the pup production of the Greenland Sea population of harp seals, Pagophilus groenlandicus. One fixed-wing twin-engined aircraft was used for reconnaissance flights and photographic strip transect surveys of the whelping patches once they had been located and identified. A helicopter assisted in the reconnaissance flights, and was used subsequently to fly visual strip transect surveys over the whelping patches. The helicopter was also used to collect data for estimating the distribution of births over time. Three harp seal breeding patches (A, B, and C) were located and surveyed either visually or photographically. Results from the staging flights suggest that the majority of harp seal females in the Greenland Sea whelped between 16 and 21 March. The calculated temporal distribution of births were used to correct the estimates obtained for Patch B. No correction was considered necessary for Patch A. No staging was performed in Patch C; the estimate obtained for this patch may, therefore, be slightly negatively biased. The total estimate of pup production, including the visual survey of Patch A, both visual and photographic surveys of Patch B, and photographic survey of Patch C, was 98 500 (s.e. = 16 800), giving a coefficient of variation of 17.9% for the survey. Adding the obtained Greenland Sea pup production estimate to recent estimates obtained using similar methods in the Northwest Atlantic (in 1999) and in the Barents Sea/White Sea (in 2002), it appears that the entire North Atlantic harp seal pup production, as determined at the turn of the century, is at least 1.4 million animals per year.

Tympanometry Revealing Middle Ear Pathology

1976 ◽  
Vol 85 (2_suppl) ◽  
pp. 209-215 ◽  
Author(s):  
Ulf Renvall ◽  
Jörgen Holmquist
Keyword(s):  
Middle Ear ◽  
Pure Tone ◽  
Screening Method ◽  
Initial Study ◽  
Predisposing Factor ◽  
Pilot Studies ◽  
Impedance Audiometry ◽  
Middle Ear Pressure ◽  
Stapedius Reflex ◽  
Temporal Bones

In order to evaluate the usefulness of impedance audiometry as a screening method for school children, two different pilot studies were performed. The results indicated that impedance audiometry (tympanometry and stapedius reflex test) was more efficient than otoscopy and pure tone screening in the detection of ears with secretory otitis media (SOM). In order to gain some more experience, an extended study of 800 7-year-olds was performed. The results from this investigation showed 6.5% pathological values with pure tone screening, 13.5% pathological values with tympanometry and 32% elevated or nonelicitable stapedius reflexes. Analysis of our observations indicates that the stapedius reflex may be too sensitive a test to be used as a screening method. Tympanometry, however, is recommended as a complement to pure tone screening in screening of children. A 6–12 months follow-up was also performed on 357 ears in which an initial study had shown a middle ear pressure of ≤ −100 mm H2O. At the repeated test 20% had pathological pure tone screening, 40% had a middle ear pressure of ≤ −100 mm H2O, 57% had elevated or nonelicitable stapedius reflexes, and 14% had middle ear effusion. The high frequency of persisting abnormal middle ear pressure and effusion in these 357 ears suggests that a middle ear pressure of ≤ −100 mm H2O can be a predisposing factor for SOM. In an experimental study on human temporal bones it was demonstrated that the tympanogram preserves its original appearance when the water level is low in the middle ear, while a higher level gives rise to a pathological tympanogram. It is also demonstrated that there is a discrepancy between the tympanometrically, indirectly recorded middle ear pressure and the middle ear pressure as measured manometrically, directly from the middle ear.

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