Insert earphones

High-performance insert earphones for EP / ERP applications

• Unique design eliminates interference with ERP / EP measurements
• Flat frequency response referenced to the sound field
• * 70+ dB isolation between ears: reduces the need for masking
• Eliminates collapsed ear canal problem
• 30+ dB external noise exclusion

* When used with a source having separate grounds for each channel -- e.g. NOT a standard PC sound card.

These specialized insert earphones have been designed to imitate the normal resonance of the open ear, and is used for speech audiometry where the goal is to reproduce the same frequency response at the eardrum for speech as would be produced in the live situation.

Why do I need these special earphones for auditory EP / ERP applications?

• Calibratable - These insert earphones have optimally-flat frequency response. So, no matter the frequency of the sound you play, you can apply a single scale factor to achieve relatively accurate control of sound-pressure at the earphone. 
• No stimulus artifact - The piezo transducer is a few inches from the electrodes so you will not see a stimulus artifact. 
• Predictable timing - The time it takes for sound to travel from the transducer to the ear is exactly one millisecond, and you can take that into account in your measurements.

Can I use standard earphones or speakers?

Standard headphones will interfere with the EEG recording - a non-starter. 

You can use loudspeakers, but we recommend against that because:

• Loudspeakers sometimes produce stimulus artifact
• Sound pressure levels depend on the exact head position relative to the speaker.
• Loudspeakers typically have irregular (not flat) pass bands, making calibration across frequencies a challenge.
• Time delay from speaker to ear depends on distance and head-position, so it is impossible to know the timing delay to the ear without carefully measuring the distance between the speaker and the ear.

As provided by Cortech Solutions, ER1 includes:

• Earphones
• Dual-mono 7' cable assembly with two 1/4" male mono phono plugs
• Adapter from dual mono plugs to one 1/8" male stereo mini-phono plug (permits use with standard PC sound card jack)
• 50 foam eartips (regular, 13 mm)
• 10 foam eartips (baby, 10 mm)
• 2 immittance probe tip adapters with tubing
• 4 front tube replacements
• Velcro clips

Technical Specifications

• 1 kHz sensitivity: 105 dB SPL for 1V rms drive
• Impedance: 10 Ohms nominal
• Acoustic Polarity: +Electrical = + Acoustic

• Typical Frequency Response (Zwislocki Coupler) - at right

Copyright © Etymotic Research, Inc.