An Interactive Digital Platform for Teaching Auditory Physiology

using Two Classes of Electronic Basilare Membrane Models

Gregor Hohenberg

, Gebhard Reiss

and Thomas Ostermann

Centre for IT, Media and Knowledge Management, University of Applied Sciences Hamm,

Marker Allee 76-78, 59063, Hamm, Germany

Chair and Institute for Anatomy and Clinical Morphology, University of Witten/Herdecke,

Alfred-Herrhausen-str. 50, D-58448, Witten, Germany

Chair of Research Methodology and Statistics in Psychology, Witten/Herdecke University,

58313, Herdecke, Germany

Keywords: Digital Learning, Basilar Membrane Model, Software, Education.

Abstract: Teaching and understanding the principles of physiology is one of the most important and complex fields in

medical education. This article describes the development of a digital learning platform for hearing

physiology with computer experiments demonstrating the perceptual masking properties of the human ear.

The basis for the development of this platform were two different hearing models: the sequential electronic

model of the inner ear described by David in 1972 and the parallel Gammatone model by Patterson from

1988. The platform was evaluated from 44 undergraduate students of audiology. On a Likert Scale from 1=

absolutely agree to 5=do not agree at all, students found the learning platform helpful for understanding

“audiological physics” (2.10 ±0.67). After working on the learning module, the physiological hearing

processes also became more evident to the students (2.24 ±0.69). They also were able to use the learning

platform independently without relevant technical problems (1.93 ±0.80). As a conclusion, the usage of such

interactive digital platforms might also lead to more efficient learning pathways which interconnect

knowledge acquisition, skill development and life experience at the same time.

1 INTRODUCTION

Teaching and understanding the principles of

physiology is one of the most important and complex

fields in medical education. Already in 1863

Helmholtz brought out his pathbreaking work “On the

Sensations of Tone as a Physiological Basis for the

Theory of Music”, which in it’s origin german

language was titled “Die Lehre von den

Tonempfindungen”, which clearly emphasized the

educational aspect (stressed by the word “Lehre”) of

his work (Helmholtz and Ellis, 2009).

What can also be seen on this historical example

is that, depending on the respective context,

physiolgical teaching implies the availability of

knowledge of a variety of related medical sciences

most of all anatomy, cell biology or biophysics. From

that knowledge base, normal physiological processes

can be explained, which is necessary to develop

students’ knowledge of disordered

pathophysiological functioning. Therefore besides of

a huge amount of background knowledge, thinking in

structural relationships is one of the essentials for

understanding physiological working principles.

As pointed out by Beard et al., (2003) the use of

electrical engineering and computer science for

creating models of physiological pathways has led to

a deeper understanding of physiological frameworks

in the last decades e. g. in modeling the blood flow

(Wong et al., 1991; Mabotuwana et al., 2007) or

human motor behavior (Lemos et al. 2004; Tagliabue

et al., 2007) to mention some examples. This line of

reasoning was taken up and refined by (Modell, 2006)

who argues, that a “view from the inside” might also

help students to develop model oriented learning

strategies focusing on causal relationships in

physiology. Thus, integration of such models into

computer-based educational strategies offer

promising new perspectives. To be efficient for

students, models should be integrated into an easy to

handle learning platform to manage the underlying

mathematical algorithms. Today such e-learning

Hohenberg, G., Reiss, G. and Ostermann, T.

An Interactive Digital Platform for Teaching Auditory Physiology using Two Classes of Electronic Basilare Membrane Models.

DOI: 10.5220/0005656901890193

In Proceedings of the 9th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2016) - Volume 5: HEALTHINF, pages 189-193

ISBN: 978-989-758-170-0

189

applications using physiological models already do

exist, e. g. simulation models to teach respiratory

mechanics (Kuebler et al., 2007) or integrative

mathematical model for circulatory physiology

(Abram et al., 2007).

This article describes the development of a special

learning platform for hearing physiology with

computer experiments demonstrating the perceptual

masking properties of the human ear. It gives some

examples on human voice processing are how they

are described using auditory imaging and presents the

results of a student evaluation of this tool. Finally

future prospects for this platform are discussed with a

special focus on web-based learning strategies.

2 MATERIAL AND METHODS

The basis for the development of our learning

platforms were two different hearing models: the

mechanico-electronical model of the inner ear

described by David (1972) and the Gammatone

model by Patterson (1987). Despite of the fact, that

these models date back more than 20 years, they both

still represent classes of current models which are

used in scientific studies. Such is the approach of

David one of the first models which used a low pass

filterbank to describe the cochlea function. It consists

of a series of 64 low pass filters with descending cut-

off-frequency with one entrance and two exits in each

filter. One exit transmits the oscillations to the next

element, while the second exit transmits the signals to

the query system and is further processed according

to the neural auditory pathway (Figure 1).

Figure 1: The functional elements of the hearing model of

David (from David, 1972).

In contrast to this approach, the gammatone model

represents the basilar membrane as a chain of parallel

switched band pass filters. The band pass filters allow

to pass sound within a certain frequency band and so

influences the spectrum of the input signal. Thus, in

contrast to the low-pass-model of David which is a

nonlinear serial appoach, sound in this class of

models is processed linear and parallely through the

filters and then processed further (Figure 2).

Figure 2: The canal model of the sound transference in the

peripheral auditive system. p(t):Input signal; ECR: Ear

Canal Resonances; H1-H2: Transference functions of the

single auditive filters; N: Number of the parallel filters;

(t)-q

(t): Source signals.

To create a basis for the development of learning

platforms based on these two hearing models, both

model classes were realized with MatLAB Version

6.5.1. On that basis the model of David and the

gammatone model were implemented as independent

PC-programs. To show the performance of the

models the technique of auditory imaging of the

basilar membrane movement over time was used for

both models.

Finally, evaluation of the didactic qualities of this

platform was carried out by a questionnaire survey of

29 undergraduate students of medical engeneering.

Following the evaluation program of the

Coordination Center Homburg eLearning in medicine

(Graf et al., 2007), we gave the students six

statements about the learning platform which had to

be judged on a five-point Likert scale from 1=

absolutely agree to 5=do not agree at all.

3 RESULTS

To show the validity of the implemented models we

first carried out simulations with pure sinus tones of

2ms and a pitch level of 500, 1000, 2000 and 5000

Hz. As can be seen in the model of David (1972), high

frequencies are presented in the upper channels

representing the region of the round window and low

frequencies can be associated with the region of the

Helicotrema. Both models also showed a very good

correspondence in their auditory images of basilar

membran movement in conjunction with the applied

signal (e.g. spoken vocal e).

Next, to introduce normal and pathological

hearing to medical students, we showed how acoustic

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Figure 3: Basilar membrane of hearing model of David (with a 0.5 kHz to 5 kHz sinus tone).

Figure 4: Comparison hearing model of David vs.

Gammatone model for the vocal ‘e’.

signals (e.g. spoken words) are processed by hearing

impaired person. First with the gammatone model.

According to the impairments we adapted the filters

to the pathological situation and compared the results

of the basilar membran movement with a

conventional threshold audiogram (Figure 5).

Due to the more physiological approach we

therefore used the David-model for auditory imaging

of hearing impairments. (Figure 6).

For evaluation purposes, we offered our learning

platform to 29 undergraduate students of audiology.

They tested the benefit of this digital platform in their

learning process. The following statements were

judged on a five-point Likert scale from 1= absolutely

agree to 5 =do not agree at all:

Figure 5: Comparison of the Gammatone model with a

threshold audiogram.

An Interactive Digital Platform for Teaching Auditory Physiology using Two Classes of Electronic Basilare Membrane Models

191

Figure 6: Comparison of the David model with a threshold

audiogram.

1. The learning platform was helpful for the

understanding of the lesson “audiological

physics”.

2. I was able to use the learning platform

independently without relevant technical

problems.

3. After working on the learning module, the

physiological hearing processes became evident

to me.

4. I would like further instruction for a more

intensive use of the platform.

5. Would you prefer to use additional carrying-on

learning platforms?

6. Did the learning module also help you to improve

your practical competences in audiology?

Figure 7 reports the judgements of the 44 students.

Figure 7: Judgements of 44 students on a five-point Likert

scale from 1= absolutely agree to 5 =do not agree at all.

A total of 34 students found that the learning

platform was helpful for the understanding of the

lesson “audiological physics” (Mean ± StDev: 2.20 ±

0.82). 35 Students were able to use the learning

platform independently without relevant technical

problems (Mean ± StDev: 2.07 ± 0.93). 32 students

reported that after working on the learning module,

the physiological hearing processes became evident

to them (Mean ± StDev: 2.23 ± 0.80). However, also

34 students claimed that further instruction for a more

intensive use of the platform would have been helpful

to them (Mean ± StDev: 2.02 ± 0.90). This goes

alongside with the fact that 36 students would prefer

to use additional carrying-on learning platforms

(Mean ± StDev: 1.75 ± 1.33). With respect to

practical skills only 22 students reported that this

digital platform also helped to improve their practical

competences in audiology (Mean ± StDev: 2.52 ±

1.02).

4 CONCLUSIONS

For more than 20 years teaching in the medical

program at Witten/Herdecke Private University has

followed the goal of introducing students to the

reality of patient care by a practical approach

(Mitzkat et al., 2007). Therefore several aspects like

problem based learning have been introduced into a

integrated curriculum. Alongside of these innovative

didactical approaches, e-learning is one of the future

prospects of medical teaching. As one component in

the teaching-framework this article describes a

learning platform for hearing physiology based on

computational models of the cochlea.

After proving the validity of our model, we

showed how our simulation can be used as a e-

learning device for undergraduate medical students

and used our simulation to demonstrate the

relationship between a tone threshold audiogram and

the basilar membrane displacement. With this

approach, students are enabled to construct a causal

relationship between the threshold audiograms and

the tone allocation on the basilar membrane. By

interfacing of different types of media, students not

only get technical informations but also impressions

how hearing pathologies restrict the processing of

auditory informations in hearing disabled persons.

The usage of such interactive learning programs

might also lead to more efficient learning pathways

which interconnect knowledge acquisition, skill

development and life experience at the same time.

Our program therefore can easily be embedded into

practical training in physiology or linked to larger e-

learning environments e.g. in interactive casebooks

on imaging systems in otorhinolaryngology

described by Grunewald et al., (2005) or virtual

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models of the human temporal bone developed by

Wang et al., (2006).

Online availability of such a platform might also

lead to an indenpendent teaching and learning of

audiology from time and place, which can be enriched

by direct care of the professional lecturer. Thus, the

integration of learning platforms like ours into

medical education can catalyze the shift toward

applying learning strategies, where teachers will no

longer serve mainly as the distributors of content, but

will become more involved as facilitators of learning

and assessors of competency.

ACKNOWLEDGEMENT

This article is dedicated to Eduard David’s 80

birthday. His model of the cochlea inspired us to start

our research and we are grateful for his engagement

and support.

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