What is the difference between a 1.5 and 2-channel audiometer?

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Written by Amplivox

Audiometers come in different variations depending on their application. Historically, an audiometer was classified as a screener (1-channel) or a diagnostic with two independent channels (2-channel) and the main differentiator was whether masking could be performed or not. 

This difference was key, as it identified whether a system was used primarily to identify hearing loss or whether it would allow for further investigation of the type of loss. The latter would provide the relevant data to be used when thinking about the patients’ rehabilitation and fitting of hearing aids. 

Audiometers have since evolved, and in recent years a new classifier has been introduced - a 1.5-channel. A 1.5-channel audiometer has many of the features and capabilities found in a 2-channel audiometer, so understanding the difference between the two is important, to avoid confusion.


The common misconception is that a 1.5 channel audiometer is significantly different to a 2-channel audiometer. However, technology has expanded to allow what is technically a 1.5-channel audiometer to perform many of the functions of a 2-channel audiometer. 

The terminology used to describe the device is often based on regional preference, as in some international markets a 2-channel audiometer will sometimes be referred to as a 1.5 channel audiometer.

These audiometers have the specific function of delivering the tone to the first channel and masking to the opposite channel only. The second channel is labelled as 0.5 in this situation, as it’s used purely for masking. There is a direct focus on core audiometry with applications towards: 

  • Tone audiometry with masking
  • Speech audiometry
  • Free-field audiometry (speech and tone)
  • Basic paediatric testing
  • Hearing aid dispensing

It’s important to note that in many instances a 1.5 channel audiometer can also replicate the functions of a full 2-channel audiometer, and as a result, will satisfy the requirements of many hearing care professionals. An example of this is the Amplivox Model 270+.


A true 2-channel audiometer (commonly referred to as a ‘full’ or ‘independent’ 2-channel audiometer) has two separate audiometry channels, which provides extra flexibility in audiological testing. 

This allows the channels to be used for all test types including masking, which can be routed to either ear, allowing the user to play any signal. 

It also has some deeper applications so the user can further investigate any identified hearing loss. Some examples of this deeper testing include:  

  • Identification of Cochlear Dead Regions 
  • CAPD (Central Auditory Processing Disorder) evaluation 
  • Advanced paediatric testing
  • Cochlear implant assessments

Examples of a full 2-channel audiometer are the GSI Audiostar Pro and Interacoustics AC40.


This really depends on your needs; it’s important to understand why you are testing and what the output data will be used for. There are other variables to consider here too, for example: 

Cost: Typically, a full 2-channel audiometer is more expensive, as in essence, it’s two full audiometers. This will also increase the annual calibration cost, so budget could be a limiting factor.

Complexity: A full 2-channel audiometer can be more complex to operate than a 1.5-channel audiometer.

Additional function: Finally, full 2-channel audiometers are often supplied with additional tests, for example, integrated speech materials, high-frequency audiometry, ABLB, Tone Decay and SISI special tests.


We offer an extensive range of dependable and accurate screening and diagnostic audiometers that provide fast and efficient testing to audiologists, hearing and occupational health professionals.

All instruments are portable and easy-to-use, providing a customised and flexible mobile or static solution. With single-click integration to many third-party Electronic Medical Record (EMR) systems, and customised data trending and analysis, hearing conservation programmes have never been easier.

For more information on our range of screening and diagnostic audiometers, please visit our audiometers webpage, contact our customer support team on +44 (0)1865 880 846 or email us.

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