<div>
<p>Half of people over 75 in the
United States suffer from age related hearing loss and have trouble understanding
speech in a noisy background. Even older adults who have normal pure tone
audiograms can have trouble understanding speech in a noisy background. Speech
is a complex sound and therefore sounds more complex than pure tones are
required to understand the differences in processing noisy speech in young and
aged individuals. Band passed noise is easily controlled and is more complex
than pure tones making it better stimulus for testing. The first place in the
ascending auditory pathway that does complex processing is the inferior
colliculus. Single unit recordings from the inferior colliculus of young and
aged F344 rats were preformed using half octave band passed noise and pure
tones. Firing rates, first spike latencies, the number of tuning peaks,
normalized peak slope, bandwidth, and Q factors were all evaluated for each unit
in response to band passed noise. For 54 of the units their responses to pure
tones were also collected. Out of 286 units recorded from young animals, 218
were responsive and 178 of them had a band passed response. Out of 193 aged
units, 145 were responsive and 134 had a band passed response. Young units had a significantly higher total
firing rate (p = 0.008) and bandwidth (p = 0.004). The normalized peak slopes
and Q factors were significantly lower in young units indicating sharper tuning
in the aged units. Pure tones elicited a stronger response than band passed
noise however, for many units the best frequency was similar for both
stimuli. These results show that aged
units are less responsive to stimuli containing multiple frequencies which may
help explain why older adults have trouble understanding noisy speech. </p>
</div>
<br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12749525 |
| Date | 03 August 2020 |
| Creators | Caitlin Elizabeth Swanberg (9193736) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Relation | https://figshare.com/articles/thesis/A_COMPARISON_OF_INFERIOR_COLLICULUS_RESPONSES_TO_BAND_PASSED_NOISE_IN_YOUNG_AND_AGED_RATS_USING_SINGLE_UNIT_RECORDINGS/12749525 |
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