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Title of Thesis

Herbert Tledemann
Institute/University/Department Details
University of Karachi/ Department of Physics
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
hearing, ear, ear system, anoa bubalis (water buffalo), resonance curves, frequency, diplacusis binauralis, basilar membrane, membrane tectoria, acoustic trauma

Different theories of hearing that have been proposed until now are not in a position to explain satisfactorily the physical properties and the operation of the ear. The purpose, the interaction of the different parts, and the performance of the many parts of the inner ear are rather obscure. This investigation has therefore, been carried out to establish (i) an interaction of all parts of the ear, and (ii) to obtain the accurate dimensions of the inner ear. This is necessary to develop a complete picture of the system. If this is done then the physical performance of the ear can be explained more explicitly.

Experiments described herein have been carried out on the inner ear system of anoa bubalis (water buffalo) as found in Pakistan. The inner ear of this animal is rather similar to that of man.

On the basis of experiments performed, a new theory has been developed and may be described as a cybernetic model.

The theory as presented is found to answer satisfactorily the following points: (i) Logic of design of all parts of the ear system, (ii) their function and performance, (iii) shape of resonance curves observed by Bekesy, (iv) frequency selectivity of ear, (v) area of maximum stimulus, (vi) sensitivity to frequency shift, (vii) similarities in audiograms of related persons, (viii) differences in tuning of the two ears (diplacusis binauralis), (ix) intensity sensitivity of ear as function of frequency, (x) influence of age on upper frequency limit, (xi) influence of age on sensitivity of ear, (xii) effects of a localized lesion of the basilar membrane, (xiii) sufficiency of deflections to cause a sensation, (xiv) masking, (xv) width of Critical band of masking, (xvi) width of band of beats, (xviii) acoustic trauma including width of damaged band, transverse location of damage, longitudinal location of damage, and (xix) comparison to vestibular apparatus.

New technique has been developed to permit the investigations.

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2960.1 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
87.85 KB
2 1 Introduction 3
956.69 KB
  1.1 Construction of the Ear System and its Working 4
  1.2 Present Status of the Current Theories and Problems arising out of them 19
3 2 Experimental Procedure 40
308.63 KB
  2.1 General 40
  2.2 Part A preparation of the Sample 41
  2.3 Part B Physical Measurements 55
4 3 Results of Observations 57
271.06 KB
5 4 Discussion and Comparison of a New Approach to the Theory of Hearing with Older Ones and the Results 67
974.88 KB
  4.1 Shape of Resonance Curves Observed by Bekesy 80
  4.2 Frequency selectivity of the Ear 81
  4.3 Area of Maximum Stimulus 83
  4.4 Sensitivity to Frequency Shift 83
  4.5 Similarities in Audiograms of Related Persons 86
  4.6 Differences in Tuning of the two Ears ( Diplacusis Binauralis ) 87
  4.7 Intensity Sensitivity of Ear as Function of Frequency 88
  4.8 Influence of Age on the upper frequency limit 90
  4.9 Influence of Age on the Sensitivity of the Ear 90
  4.10 Effects of a Localized Lesion of the Basilar Membrane 91
  4.11 Proof that the Amplitudes of the Membrane Tectoria are sufficient to cause a sensation 92
  4.12 Masking, Critical Band of Masking and of Beats 98
  4.13 Stepwise Auditory Sensations (Quantization ) 104
  4.14 Acoustic Trauma 105
  4.15 Stimulation of Transducers by Flow of Lymph 111
  4.16 Comparison to Vestibular Apparatus 111
6 5 Conclusions 112
49.77 KB
7 6 Acknowledgements 114
28.92 KB
8 7 References 116
604.88 KB