Hearing Loss and Central Auditory Processing

59 Conductive Hearing Loss

Learning Objectives

Be able to describe the possible causes of conductive hearing loss.

Understand the impact of it in daily life.

Know what the mastoid bone is and how can it be used to distinguish conductive hearing loss from sensorineural hearing loss.

Conductive hearing loss is less common but more likely to be fixable. It is caused by damage to mechanical structures of the outer ear (e.g., extraordinary wax build-up or over-production of skin; both of these are uncommon) or the middle ear (e.g., ruptured tympanic membrane which produces 30-40dB loss; fluid due to infection; damaged, missing, or ossified ossicles).

The mastoid part of the temporal bone is the posterior (back) part of the temporal bone, one of the bones of the skull. The mastoid process is located posterior and inferior to the ear canal. It forms a bony prominence behind and below the ear.

The most obvious effect is that you can’t hear quiet sounds, but hearing loss is more complicated than that! People with hearing loss have more difficulty understanding speech in noise (can’t “hear out” the words). Different frequencies are affected differently and dynamic range is compressed (“loudness recruitment”), which means people with hearing loss have a hard time enjoying music.

Many people suffer from conductive hearing loss because of age, genetic predisposition, or environmental effects. With conductive hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles. These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur.

Conductive hearing loss can be distinguished from sensorineural hearing loss by measuring hearing through bone conduction: you put a speaker against the mastoid bone behind the ear, and if hearing through bone is normal, or there’s an “air-bone gap” (hearing is better through bone than air), then at least part of the loss is conductive.

The profile of a skull is shown. The mastoid bone is highlighted in red. The mastoid bone is just behind your jaw and below your ear.
Figure 6.1.1. Mastoid process, lateral view. Conductive hearing loss can be tested by placing a speaker on the mastoid bone. (Credit: Database Center for Life Science (DBCLS). Provided by: Wikimedia Commons License: CC BY SA)



OpenStax, Psychology Chapter 5.4 Hearing
Provided by: Rice University.
Download for free at http://cnx.org/contents/4abf04bf-93a0-45c3-9cbc-2cefd46e68cc@5.103.
License: CC-BY 4.0

Cheryl Olman PSY 3031 Detailed Outline
Provided by: University of Minnesota
Download for free at http://vision.psych.umn.edu/users/caolman/courses/PSY3031/
License of original source: CC Attribution 4.0


Icon for the Creative Commons Attribution 4.0 International License

Introduction to Sensation and Perception Copyright © 2022 by Students of PSY 3031 and Edited by Dr. Cheryl Olman is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

Share This Book