Tuesday, August 11, 2020

Audiometer

Hi friends!!!

In our previous blog, we have discussed about glucometer. Please check out for the link given below.

Glucometer

In today's blog we are going to discuss about audiometer.


The audiometer is an important equipment in ENT hospitals to measure hearing ability of the patients. Therefore it is important for every healthcare professionals to know about audiometer.

Let's get into the topic.


INTRODUCTION

The early audiometer was introduced in 19th century and was called as induction coil audiometer. Audiometer was invented by Carl Seashore in 1899 as an instrument to measure keenness of hearing. Max Wien introduced the concept of plotting frequency versus sensitivity as a audiogram chart in 1903.



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WHAT IS AUDIOMETER?

The audiometer is an electronic device used to evaluate the hearing threshold of the person and to quantify the degree of hearing loss. The audiometer is used by a experienced audiologist. As a subjective device audiometer requires a response from the patients as a feedback.

The unit of measurement for sound intensity is decibel (dB) The human ear can hear minor sounds such as whispers of about 20 Db and larger sounds between 140 and 180 dB. The tone of the sound is measures in cycles per second. The unit for measurement of tone is Hertz. Humans can generally hear tones between 20 – 20000 Hz.


WHAT IS SUBJECTIVE OR OBJECTIVE AUDIOMETRY?


SUBJECTIVE AUDIOMETRY

The subjective audiometry depends on the cooperation from the patients side. It relies upon feedback given by the patients. The feedback may be either quantitative or qualitative. Example: Pure tone audiometry, speech audiometry.



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OBJECTIVE AUDIOMETRY

The objective audiometry is based on the physical, acoustic or electrophysiologic measurements. This type of audiometry does not depend on the feedback and cooperation from the patients. Example: Tympanometry, Acoustic reflex test.


HOW DOES AUDIOMETER WORKS?

The audiometer usually sends recorded sounds or audios at a changing frequency rates and amplitudes to the headphones connected to the patients. In turn receives the patients feedback to prepare a audiogram which represents the patients level of responsiveness of patients, voice comprehension, speech understanding and hearing threshold etc.


WHAT ARE THE TYPES OF AUDIOMETER?


SCREENING AUDIOMETER

Screening audiometer is used to identify the potential level of hearing loss. The screening audiometer uses pure tone audiometry and specifies whether hearing loss has occurred or not.

DIAGNOSTIC AUDIOMETER

Diagnostic audiometer is used to identify and quantify hearing disorders. It is also used to identify the possible origin and causes of hearing loss. Diagnostic audiometer measures air, bone and speech threshold levels and indicate specially where the hearing loss has occurred.


WHAT ARE THE PARTS OF AUDIOMETER?


OSCILLATOR

The oscillator is used to generate pure tone at different frequencies from 125 Hz to 8000 Hz. Variation may be ±3%.

ATTENUATOR

The attenuator is used to control the intensity level of the signal usually from -10 dB to a maximum output level. The maximum output levels for ear phones are 85 dB at 125 Hz,  105 dB at 250 Hz.

INTERRUPTER SWITCH

The interrupter switch is used to turn ON and OFF the sound and control the duration of the sound.

FUNCTION SELECTOR

The function selector is used to change between air, bone and speech sounds.

FREQUENCY SELECTOR

The frequency selector is used to select a particular frequency required for the stimulus.

TALK FORWARD

The talk forward is used to talk to the patient through the headphones.

PRESENTATION INDICATOR

The presentation indicator is used to change the tone in steady state, continuous or pulsed continuous mode.

OUTPUT TRANSDUCER

The output transducers may be in the form of ear phones, conduction receiver and loud speakers to enable the patients to hear the sounds produced by the audiometer.


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WHAT ARE THE COMPANIES MANUFACTURING

AUDIOMETERS?

ATMOS Medizin Technik.

AURITEC.

Benson Medical Instruments.

Echodia.

Amplivox.

Biomed Jena.

 

NOTE: The audiometer should satisfy the IEC 60645 (International Electrotechnical Commission) manufacturing standards and should also satisfy the performance and calibration requirements as stated by ISO 8253 (International Standard Organization), ANSI standards (American National Standards Institute) and AEDA (Spanish Audiology Association).


Now I hope you have acquired some knowledge about audiometer. We will discuss in detail about types of audiometric tests  in our next blog.


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