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ISLAMIC MEDICAL EDUCATION RESOURCES 04

0012-HEARING (SAMU) AND EQUILIBRIUM, (ISTIWA)

Lecture to 2nd year students on 1st December 2000-11-29 by Professor Omar Hasan Kasule Sr.

A. CONCEPTS

HUMAN HEARING

The Qur'an has used the word sam'u in the verb and normative forms to refer to human hearing (p 379-380 2:93, 2:104, 2:181, 2:285, 3:186, 3:193, 4:46, 4:140, 5:7, 5:41-42, 5:83, 5:108, 7:204, 8:20, 9:6, 9:47, 10:31, 10:67, 11:24, 12:31, 16:65, 17:47, 19:98, 20:13, 20:108, 21:2, 22:73, 24:12, 24:16, 25:12, 26:25, 28:55, 28:71, 30:23, 32:12, 36:25, 39:18, 41:20, 41:26, 63:4, 64:16, 68:51,76:2). Humans perhaps start in utero. Neonates probably hear and understand; it is recommended to pronounce adhan in their ear at birth (KS 71). Dead humans do not hear (27:80, 30:52, 35:22, MB#674) except in special circumstances. The prophet addressed the dead polytheists at Badr and said that they heard him (KS p. 114: Bukhari K64 B8 & B12; Muslim K51 H76 & H77; Nisai K21 B116, Tayalisi H403) and said that they heard him. Ordinary humans cannot hear the dead but the Prophet is reported to have heard noises from the grave.

 

HEARING AND INTELLECT, sama’u & ‘aql

The sense of hearing is related to the intellect, communication, and self-protection. The Qur'an in many verses has mentioned hearing with intellect at the same time (p 380-381 2:7, 2:171, 16:25, 6:46, 7:195, 10:42, 16:78, 17:36, 22:46, 23:78, 25:44, 32:9, 45:23, 46:26, 50:37, 67:10, 67:23). The relation between hearing and intellect should not be difficult to appreciate. Humans have the most developed intellectual and communication functions. Human communication uses words to describe very complex and sophisticated abstract concepts. Thus humans must hear words to be able to communicate ideas and concepts. This is in addition to hearing other aural sensory inputs from the environment. In comparison to vision, the sensory input from hearing is of a higher quality because it is human language. Ability to hear and process language places humans far and above other animals and enables them to build social relations and a civilisation in which there is inter-generation transmission of knowledge and experiences.

 

MISUSE OF HEARING, ta'atil al samau

The Qur'an has dealt at length with metaphorical deafness (6:25, 17:46, 18:57, 31:7). Humans can deliberately refuse to listen to the truth or Allah may close their ears to the truth because of the evil in their hearts, ta'atil al samau (p. 381 2:7, 6:36, 7:100, 7:179, 7:198, 8:23, 10:42, 18:101, 21:45, 27:80, 30:52, 31:7, 32:26, 35:14, 35:22, 41:4, 43:40, 45:8, 45:23, 47:16). Deliberate refusal to listen has been likened to the Qur'an to putting wax in the ears (17:46).

 

HEARING AND DISOBEDIENCE

In Qur'anic terminology listening or hearing are very akin to obedience and compliance. Refusal to hear is associated with rejection and disobedience (p. 379 2:93, 2:104, 2:285, 4:46, 5:7, 39:18, 64:16).

 

NON-HUMAN HEARING

Hearing is not confined to humans. Allah hears (p. 678 3:181, 20:46, 26:15, 43:80, 58:1). Angels have the ability to hear and have undertaken communication with prophets. The jinn can hear (15:18, 46:29-30, 72:1, 72:9, 72:13). Other members of the animal and plant kingdoms also have varying abilities to hear and react to sound. Inanimate objects do not hear. Idols that have been worshipped by humans in many societies and in all ages are not living and cannot hear (19:42, 26:72, 35:14).

 

B. ANATOMICAL AND PHYSIOLOGICAL ASPECTS

THE EAR

The Qur'an mentioned the ear as an organ of hearing (p. 278 2:19, 6:25, 7:179, 7:195, 17:46, 18:11, 18:57, 22:46, 22:46, 31:7, 41:5, 69:12, 71:7). Most verses about hearing are about deliberate human refusal to use the ears to hear words of wisdom.

 

TYPES OF SOUNDS

Some sounds are pleasant to the ears such as singing, ghina, and recitation of the Qur'an in a good voice. The Prophet (PBUH) used to like listening to the Qur'an (KS 439: Bukhari K65 S4 B9; Bukhari K66 B32 & B33 &B35; Abu Daud K20 B13). He ordered his companions to decorate the Qur'an using the voice, tazyiin al Qur'an bi al saut (KS 444: Nisai K11 B83; Tayalisi H738). Some sounds are unpleasant such as shouting, and the sound of the donkey, saut al himaar (31:19). It is desirable to hear loud sounds such as in adhan (KS 70: Bukhari K10 B5; Bukhari K7 B52; Abu Daud K2 B31; Nisai K7 B14; Ibn Majah K3 B3; Muwatta K5 H5). In some cases soft sounds such as the response to adhan are preferable (KS 71: Bukhari K10 B7 &B8; Bukhari K65 S17 B11; Muslim K4 H10-13; Abu Daud K2 B36-38; Tirmidhi K2 B40 & B42 & B43; Nisai K7 B33-38; Ibn Majah K3 B4; Darimi K3 B9 & B10; Muwatta K3 H2; Tayalisi H2214). The recitation of Qur'an in some salats is aloud and is soft in others.

 

SOURCES OF SOUND

There are several sources of sound in the environment: thunder, rain, wind, sea waves, waterfalls, movements of plants and animals, human activity, human voice, and man-made sounds. It is a sign of Allah's power that a human sound in whatever language it may be will be recognized as human by all other humans.

 

SOPHISTICATED AUDITORY SYSTEM

The ear is protected deep in the skull. Air vibrations move the tympanic membrane that moves the ossicles that in turn move the fluid of the inner ear. Hearing receptors in the semicircular canals move with the movement of the fluid and this results in sending sensory messages to the auditory cortex. Receptors in the inner ear can detect gravity, acceleration, and sound waves. The eustachian tube allows equalisation of pressure between the atmosphere and the middle ear.

 

PHYSICS OF HEARING

Human hearing depends on sound waves that strike the eardrum and cause mechanical movements that are eventually transformed into electro-chemical impulses. The speed of conduction of sound varies by the density of the medium: air, water, and solids and this affects human hearing. The characteristics of sound can be described by its speed, loudness, and pitch. The speed varies by the medium of conduction. The speed of sound at the sea level is 344 meters per second. It increases with temperature and altitude. The speed is higher in water and solid mediums. The loudness is related to the amplitude. The pitch is related to frequency

 

BI-AURAL HEARING

It is a blessing of Allah that humans have two ears such that the hearing of one is slightly different from that of the other. This enables judgement of distance from the source of sound. It also helps in appreciation multi-dimensional stereo sound.

 

C. LIMITATIONS OF HUMAN HEARING

PHYSICAL LIMITATIONS

Human hearing is not the most sensitive in the animal kingdom. Humans have a narrow range of frequencies that they can hear. Very loud or very soft sounds cannot be heard. Human ability to discriminate mixed sounds is limited. When noise is constant it becomes part of the background and is ignored.

 

METAPHORICAL LIMITATIONS

Human hearing is also limited in a metaphorical sense due to moral deficiency (p 381 2:7, 6:46, 7:179, 8:21, 11:20, 18:101, 23:24, 28:36, 35:14, 35:22, 45:23, 52:38).

 

LOSS OF ABILITY TO HEAR SOME HUMAN SOUNDS

Newly born babies are able to hear and learn all the sounds found in all human languages. They could theoretically speaking be able to learn many languages and speak them with native fluency. As they grow they concentrate on those sounds spoken by their parents or other persons in the immediate social environment and they gradually lose the potential for the remaining sounds. Thus an adult who learns a new language will always speak it with an 'accent' because the repertoire of sounds available to the adult is limited.

 

WISDOM OF HEARING LIMITATIONS

The hikmat behind limited human hearing is to protect the sensory perception and the cerebral cortex from over stimulation with a lot of extraneous environmental stimuli.

 

D. THE SENSE OF GEO-BALANCE

THE CONCEPT OF BALANCE

The sense of geo-balance relates to the Qur'anic concept of balance, Istiwa (43:13). There are two types of balance, static and dynamic.

 

STATIC BALANCE

Humans are able to stand on two legs and achieve balance by use of their musculo-skeletal system.

 

DYNAMIC BALANCE

Humans are able to maintain their balance when walking or running. This requires very careful coordination that involves the sensory and locomotor systems

BALANCE and HUMAN CIVILIZATION

The sense of balance is needed for the bi-pedal upright posture that is unique to humans. Human civilisation as we know it would not have succeeded without this upright posture. Humans are the only animals that can stand upright for prolonged periods of time and are also able to walk upright without falling or making any special conscious efforts to stay upright. Human ability to move on the lower limb frees the upper limb for manipulation and making tools.

 

NEURO-MUSCULAR CONTROL

Static balance requires less neuro-muscular coordination than dynamic balance when walking, running, or working with tools and machines.

 

D. PATHOLOGY

DEAFNESS

The Qur'an has described both physical deafness, samam, and metaphorical deafness; the distinction between the two forms is not major because the end-result is the same, non-communication of vital messages of truth.

 

The Qur’an described physical deafness, samam (p. 716-717 19:42). It however gave more space to description of moral deafness which is associated with disobedience and is considered a form of misuse or under-use of the hearing faculty, ta’atil al sam’u (p 716-717 2:7, 2:18, 2:171, 5:71, 6:25, 6:39, 7:179, 7:195, 7:198, 8:21-23, 10:42, 11:20, 11:24, 11:108, 17:97, 18:101, 19:42, 21:45, 22:46, 25:44, 25:73, 26:72, 27:80, 30:52, 31:7, 35:14, 41:5, 43:40, 45:8, 45:23, 47:23).

 

DISEASES OF THE EAR

Acute otitis media is bacterial in children. When it becomes chronic it turns into cholesteatoma. Otosclerosis is a familial condition that is an abnormal bone deposition in the oval window of the middle ear causing immobilisation and impaired hearing. Other ear diseases are aural polyps, labrynthitis, and carcinoma of the external ear (rare).

 

HYPER-ACUSIS

The human ear is normally not sensitive to a wide range of sounds in the environment. If it were more sensitive, humans would suffer from information overload that the brain could not process. Those suffering from the condition of hyperacusis that is pathological increase of hearing acuity best appreciate this bounty of Allah

Professor Omar Hasan Kasule, Sr. December 2000