Phonosensitivity and listening tests (Feldman, Bordeaux 1981)

Communication presented at the Congress of the Association Française d’Audio-Psycho-Phonologie*,* Bordeaux, 22 November 1981*, by* Dr David Feldman (8 rue du Général Koenig, 33600 Pessac).

Phonosensitivity and listening tests. Why does the traditional listening test — limited to air conduction and to verbal reactions — miss the essential? Presentation of a multi-modal phonosensitivity test elaborated under the patronage of the AFAPP.

The importance and limits of listening tests

Listening tests are of capital importance in the various domains of acoustic therapy, for they are the fundamental instrument in the diagnostic process and the principal guide for the establishment of therapeutic approaches.

The objective of a listening test is to measure and interpret the reactivity of the organism to a sonic stimulus injected through the ear. The stimulus may be of a pure, linguistic or musical nature, of variable duration and generated at an equally variable intensity. The divergences between the acoustic and significative nature of the stimulus and the externalised reactions (classically verbal or graphic) of the subject are subsequently interpreted as being of organic, functional or psychological origin.

The test indicates the existence of a pathological process in the auditory sensory modality and — by identifying roughly the nature of the process — helps to plan clinical treatment. The periodic application of the test allows interpretation of the progress and efficacy of the clinical approaches.

The limitations of traditional tests

The importance of the listening test is therefore indisputable. It is precisely the central role of the listening test that imposes rather strict conditions on its organisation and content. A number of limitations appear from the start:

Traditional listening tests confine themselves to injecting the sound exclusively through the auditory pathway, and preferentially by air conduction.
The stimuli are very often limited to the pure tone, to global linguistic discourse or to global musical discourse.
The externalised reactions of the subject are characteristically restricted to verbal and graphic modalities.

Now, we know that the entire surface of the body is dotted with sensory terminations sensitive to vibratory and sonic stimuli. While admitting the special adaptation of the ear to the task of sound reception, it is nonetheless true that the whole body is, in a sense, phonosensitive.

The phonosensitivity of the whole body

The depolarisation of phonosensitive neurons at the surface of the body implies the possibility of a bodily reaction to sound in the circuit of autonomic reflexes — of which the brain becomes conscious only afterwards. The message that reaches consciousness is already complex, for it contains the sonic element and the sensations of the reflex action on the great neuro-physiological functions. That is to say that the original sonic stimulus has been filtered by a whole series of complementary, almost simultaneous interoceptive messages.

In turn, the interoceptive process and the alterations produced on the great functions release quantities of neuro-transmitters whose effect on the electro-chemical activity of the brain affects auditory reception and the interpretation of the sonic message. By experimentally blocking the phonosensitivity of the nervous pathways beyond the ear, the sound received by the auditory pathway appears to provoke these involuntary responses whose proprioception has a direct effect on cortical activity.

It is necessary to insist on the “non-intellectualisable” nature of these reactions, born in interoception, for their action on the verbal and graphic expression of the subject is extremely subtle. By contrast, their action is directly measurable by means of myography, cardiography, galvanometry and associated techniques.

The role of the emitter

Any complex sonic message — such as linguistic or musical messages — permits at least two levels of analysis: semantic and acoustic. The message will be interpreted (and the reactions will be programmed) by the subject not only according to his cultural codes and lived experiences but also according to the proprioception of the involuntary reactions and of the alterations of the great neuro-physiological functions produced by the individual sonic elements contained in the message.

This accounts for the observation of differentiated reactions in a single subject following the reception of a message whose significative content remains stable but whose emitter changes. The same musical phrase sung by a man, and afterwards by a woman, determines different reactions in the same subject. This same phenomenon has been observed with respect to linguistic messages, and — to a less dramatic degree — with respect to structured sounds.

Other factors intervene in this process:

the significative content of the message;
the linguistic or musical style of the message;
the family or friendship ties between the subject and the emitter;
the form of sound injection: through headphones, through a vibrator, in the aerial medium, in an aquatic medium, etc.

The Phonosensitivity Test (AFAPP)

In consideration of these facts, the listening test becomes in effect a phonosensitivity test. To orient better our study of the elements composing such a test, here are the result sheets of a test elaborated under the patronage of the Association Française d’Audio-Psycho-Phonologie.

The nine categories of stimulus

Pure tones (classical audiometry).
Language (unknown voice) — SRT, SDL, MCL/TD tests.
Unstructured sound (various noises).
Structured sound (identifiable sounds: broken glass, horn…).
Convergent music (reassuring).
Divergent music (insecuring).
Spoken voice timbres: mother, father, brothers/sisters, therapeutic staff.
Sung voice timbres: Soprano, Alto, Tenor, Bass (S/A/T/B), and combinations (SATB).
Instrumental timbres: percussion, woodwind, strings, brass, piano, organ.

Three modalities of injection

Each of these stimuli is injected three times according to three modalities:

AC (Air Conduction) — through headphones, the classical auditory pathway. Note: the mere fact of placing headphones on a subject already provokes important physiological and psychological alterations (cardiac and respiratory rhythms, feelings of enclosure and anxiety). A test exclusively by AC therefore risks presenting data already transfigured by the simple effect of wearing the headphones.
BC (Bone Conduction) — through cranial vibrators. The pressure on various parts of the skull may evoke non-auditory responses, comparable to those observed with headphones.

Vibrators on the large bony planes — spine, sternum — or on the great hollow cavities (abdomen).
Vibrating bath — vibrators on the external faces of a warm-water bath into which the subject is plunged. Precise but costly; psychological objections (nudity, modesty) and unusual liquid medium.
Pneumatic couch — the subject lies on an inflatable plastic couch, with external vibrators, sound waves propagating in the inner air medium. Measurements made back and belly. The most practical compromise: amplification less than for liquid transmission, less notable psychological problems.

The nine categories of stimulus in detail

1. Pure tones: audiometry

This first category belongs to the domain of classical audiometry. The results — by air and bone conduction — are indicated on a standard audiogram.

2. Language

Three tests intended to determine the subject’s capacity for the perception of language:

SRT (Speech Reception Threshold) — intensity threshold required to recognise a list of two-syllable words.
SDL (Speech Discrimination Level) — threshold to recognise a representative list of mother-tongue phonemes (generally, threshold = 50% correct responses).
MCL/TD (Most Comfortable Level / Threshold of Discomfort) — tolerance level, normally found between 50 and 70 dB above the SRT.

For a patient unable to repeat — for example a child — one may give him a graphic series for the word in question, or ask him to write or draw each word.

3 and 4. Unstructured and structured sounds

The sounds are recorded on magnetic tape at audiometric zero and injected by the air pathway through the audiometer. The responses reach the threshold when the subject becomes able to identify each sound — by verbalising or by reference to drawings.

5 and 6. Convergent and divergent music

These categories aim at the subject’s reactions to a musical stimulus — variable according to the melodic, harmonic, rhythmic and instrumental organisation of the piece. Distinction between:

high reassuring reactivity (convergent music): fundamental tones of the melodic line lying within the passbands of the human spoken voice, simple melodic structure, major harmonic structure, few dynamic modulations;
high insecuring reactivity (divergent music): fundamental tones outside the bands of the spoken voice, complex melodic structure, minor or dissonant harmonic structure, frequent dynamic modulations.

A few remarks:

Music played by an ensemble of string instruments is convergent or divergent according to these parameters; played by an ensemble of wind instruments, it is divergent by definition.
Music played on a solo, non-harmonising instrument without accompaniment: the convergent reaction is admitted when the melodic line lies in the octave above or below the octave of the spoken voice passbands.
To reduce distorted reactions, one avoids the use of music excessively associated with a particular socio-cultural context (military marches, broadcast theme tunes). Lullabies and folk music are reserved for the therapeutic programme.
Musical stimulations are injected without filtering during the test (the aim is to evaluate the global response). Selective filtering is by contrast used in the therapeutic approaches.

7. Familiar spoken voice timbres

This category concerns the characteristics of the voices of the persons with whom the subject lives a special affective relation: mother, father, brothers, sisters, and — when the patient is already in treatment — the clinical staff directly in charge of his case.

8. Sung voice timbres

The pieces chosen are normally folk songs from the patient’s country of origin to avoid the intellectualisation of the musical content. Four tessituras isolated or combined: Soprano (S), Alto (A), Tenor (T), Bass (B), and the SATB combination.

9. Instrumental timbres

The same piece is played by various instruments — percussion, woodwind, strings, brass, piano, organ. Folk-song melodies are chosen to fix the subject’s attention on the characteristic timbre of each instrument or group of instruments.

The importance of the subject’s differential reactivity with respect to instrumental or vocal timbre has not been sufficiently appreciated. Example: a subject who accepts without abnormal reactivity a piece played on the oboe but who reacts extraordinarily to the same piece played on the organ — an instrument he associates with a phobic reaction linked to his childhood religious experience.

In all categories of the test, the stimuli are injected at “audiometric zero” and without filtering — these variables being reserved for therapeutic approaches.

The ten categories of response measured

The organism reacts to the sonic stimulus in a much more varied way than the verbal and graphic reactions traditionally measured. The ten principal categories of response are:

Graphic reaction — differentiated between writing and drawing. Writing, being an activity of very high ocular-manual coordination, undergoes under sonic stimulus subtle calligraphic alterations that are difficult to repress consciously. For drawing: exploitation of the field offered, choice of graphic instrument, chromatic composition, nature of strokes, figurative content.
Structured motor reactions — the subject performs a series of psychomotor activities (associations of geometric forms) under sonic stimulation. Parameters: reactive time, global time, quality of responses.
Voluntary motor reactions — the subject is invited to move freely and to settle into postures of his choice. Evaluation in terms of rhythm, speed, intentionality of movements and stereotyping of postures.
Verbal reactions — the subject verbalises freely during the sonic injection. The discourse is recorded and analysed according to the Pittenger scale.
EEG — through electro-encephalography, the spontaneous activity of the large pyramidal cells of layers IV and V of the cortex is analysed.
Cardiac activity.
Respiratory activity.
Thermal activity of the body. (The cardiac, respiratory and thermal alterations to the sonic stimulus affect the general metabolism of the organism — including cerebral metabolism, particularly essential in the equilibrium of psychic states.)
Involuntary motor reaction — sound produces involuntary reactions on smooth musculature, starting from the depolarisation of cutaneous nerve endings and passing through reflex arcs. Reflexes proprioceptively perceived by the organism, translated into measurable alterations on the parameters of the great functions.
Biochemical study — blood and urine samples during the sonic injection, allowing identification of the neuro-transmitters affected by the sonic stimulus and — thereby — partial identification of the nature of possible blockages manifested by the subject in the central nervous system. The study of psychochemistry is always incomplete, but its importance is indisputable.

Effect of the placing of headphones (experimental illustration)

To show the importance of the modality of injection, here is a simple experiment: a placement of headphones (without any sonic stimulus) during three minutes, on eleven subjects, measured on three planes:

Physiological plane — cardiac rhythm: seven subjects manifested an increase, one alone remains insensible, one manifested a decrease.
Psychomotor plane — execution time of a simple task of association of geometric forms: two subjects improved their time, eight worsened it, one alone remains insensible.
Psychological plane — verbalised manifestations of states of mind.

A phonosensitivity test carried out exclusively by air conduction under headphones therefore risks presenting data already transfigured by the mere effect of the placing of the headphones. The exploitation of the bony and bodily pathways serves not only to broaden the listening test by the available pathways for injecting sound — it also controls for the interference of the modality of injection in the results.

Conclusion

The use of the phonosensitivity test to date allows the affirmation that it:

Seems to fill the lacunae of the parameters measured in traditional listening tests — parameters whose importance is yet fundamental.
Provides data concerning the specific reactions of a subject to a sonic stimulus — whose exactitude and amplitude seem to ensure reliable bases for the elaboration of an individualised acoustic therapeutic programme, according to the nature of the condition as well as to the always unique personality of the patient.

This phonosensitivity test has been used in several countries, under very varied conditions and in various domains: re-education, psychiatry, clinical psychology, acoustic therapy. A statistical summary of the experiences is available from the author.

— Dr David Feldman, 8 rue du Général Koenig, 33600 Pessac. Communication at the AFAPP Congress, Bordeaux, 22 November 1981. See also by the same author: Introduction à la musicothérapie* (Brussels: Institut International d’Éducation Spécialisée, 1979);* Bases psycholinguistiques de l’apprentissage de la lecture et de l’écriture* (1978).*