Speech Audiometry - Pure Tone Audiometry and Loudness Tests

Our ears are one of the most complex organs in our body that is akin in its mechanics only to the eye. The ear consists of three sections: the outer, middle, and inner ear. Sound comes in from outer ear and vibrates the eardrum or tympanium. The vibrations are then sent to a circular organ called the cochlea. Here the vibrations are transferred to a fluid medium and the movements of this fluid cause celia or fine hairs to move. The movements are then converted into neural impulses and then sent to the brain for deciphering into the sounds that we can hear. Anything from ear wax to nerve damage can dislodge this fine balance.

Testing for auditory capacity is done by two tests called the Pure Tone Audiogram and speech audiometry. Both of these tests are conducted with a pair of headphones in a closed room where the thresholds of hearing are tested through varying frequencies and decibel levels. Speech audiometry is dividing into further categories. Speech detection is the first part of the test. Special words that have a constant modulation are played into the headphones, and the objective is for the test subject to simply be able to identify the sound at the lowest level. The next test is the speech recognition test. Here words are said and the test subject will have to identify and repeat the words that were stated. Suprathreshold word-recognition is then performed where conversations are played out at a specific, realistic modulation, and the person is asked to identify and repeat the words that were said. The next test is the sentence test. Sentence tests are important because a large part of our hearing involves using a cache of memories to string out words in a sentence. This means that even without complete concentration, we tend to hear words and sentences correctly. To avoid this affecting the tests, synthetic sentences are played out in which the sentence makes absolutely no sense and therefore forces the test subject to hear a sentence properly. Speech perception in noise tests one’s ability to identify that something is being said amidst other clutter.

The final tests are the loudness tests. These measure the level of loudness that a person can bear and the level that a person would cringe at. The test is quite difficult to conduct in children with hearing difficulties and for this reason, standardized words are used.