Lab Report 3 – Lab Report Example
Audiometry Lab. lab session Introduction The standard way of representing the hearing ability or hearing loss of a person is by using an audiogram. Many of the audiograms that exist range between 100 Hertz and 8 KHz. These are the frequencies important for clarity in understanding of speeches and thus plot the threshold of the process of hearing in relation to the standard curve that represents the normal curve of hearing (Rimmer, 2004). Audiograms are normally produced using a number of test equipment such as the audiometer. This allows for different frequencies to be presented to the subject normally over headphones that are calibrated at specified levels. The intensity of the sound is measured in decibels (bBHL). At 0 decibels, the intensity is soft and any normal person can detect about 50% of the sounds. Frequency on the other hand is considered low at 25 Hertz to 250 Hertz and beyond 4 kHz, hearing loss becomes very intensive (Rimmer, 2004).
In this test, different tones will be presented at specified frequencies and intensities. When the person hears the sound, they press a button so that the experimenter can know that they have heard it. The sound that has the lowest intensity that can be heard is recorded. The audiometric tests will be used to determine the hearing levels of the subjects using the aid of an audiometer but this process may also measure the ability of discrimination between the different intensities of sound, recognition of pitch and distinguishing pitch from background noise. The results that are obtained can be used to diagnose the loss of hearing or the ear disease using an audiogram. The audiometric tests help to determine the hearing ability of the participants.
Figure 1: The audiometer
To assess the hearing level by creating an audiometry chart.
Instruments and Materials
2. An audiometry chart- Belton model 12D/9D
a) Ensure that the test environment is quite and free from noise.
b) Connect the audiometer to the earphones and ensure that the loudness on the audiometer is set to minimum. Before turning on the audiometer, allow the person listening to familiarize himself with the environment.
c) Turn on the audiometer to 125 Hertz. When the person listening hears the sound, he should indicate that he has heard it.
d) Perform the tests on both the right ear and the left ear.
e) Increase the frequency to 250 Hertz, 500 Hertz, 750 Hertz and 1000 Hertz and plot the results.
From the graph of the left ear, the hearing pattern on the left ear has a bilateral normal slope in relation to hearing loss. Under listening conditions that are considered perfect, the listener is likely to miss just a few words off and on because of the failure to capture some words. Under nosy conditions, the listener will experience more difficulty in listening to the words. At 4000 Hz, noise induced hearing loss can be noted from the graph with the curve dipping downwards. The hearing loss in the right ear can therefore be said to be moderate.
From the graph of the right ear, the bilateral normal slope on the graph is moderate and hence shows an average amount of hearing loss. The right ear is able to capture some words at low frequencies but misses some. The listener is also able to distinguish between some words while he is unable to distinguish between others. Therefore the hearing loss in the right ear ranges from mild to moderate.
The hearing loss between 125 Hertz and 750 Hertz is symmetrical for both ears. Beyond 750 Hertz, the hearing loss increases and dips at 4.0 KHz for the left ear while for the left ear, the hearing loss changes in intensity beyond 750 Hertz.
From the experiment, the objective has been met and we have been able to assess the hearing level by creating an audiometry chart. The hearing loss for the right ear has been determined and compared to that of the left ear. The hearing loss in the two years can therefore be said to be symmetrical from 125 Hertz and 750 Hertz. The hearing loss can however be affected by other external factors such as noise, environmental factors such as wind and the state of health of the person. These factors must be taken into consideration while giving the findings from the tests.
Thomas W. Rimmer, Hearing disorders and audiogram interpretation (2004). Retrieved from: http://www.audiologist.org/_resources/documents/diabetes/Hearing%20Disorders%20and%20Audiogram%20Interpretation.pdf. Accessed on 28th April 2015.