Hearing Threshold Changes

Changes in hearing thresholds were recorded during a specific time span for a broad population ranging in age from 47 to 90 years. The data was examined and documented. The pure tone thresholds, which are when there is no additional external noise at frequencies ranging from 0.5 to 8 kilohertz, were thoroughly analyzed while taking baseline testing into account. In a span of ten ears, frequencies of 2.5, 5, and 10 were tested. It was shown that there were significant variations in the threshold between the ages of 56 and 69 (younger age), particularly for higher frequencies. Also, the opposite happened with the older age gap that is between 70 to 89 years where the changes in the hearing threshold were greatest for lower frequencies. An audiometric, device was used to measure the hearing of both the left and the right ear assuming that one ear that is the left one was defective. Across audiometric frequencies of 0.5, 1, 2, and 8 posted similar changes for both men and women. Audiometric frequencies of 4 and 6 posted rather different results where the changes remained constant in men while for females, age 48-59 had an increase in the threshold and 60-69 years tended to level off. Apart from using gender and age difference to determine changes in the hearing threshold, baseline threshold could also be utilized for the same reason.

Introduction

Absolute threshold of hearing is described as the lowest level of sound of a pure tone for an ordinary person’s ear who has normal hearing can be able to hear when no any other sound is present (Brant 1990). It closely relates to the sound that can be heard by the individual. The absolute threshold of hearing is not a distinct point but rather is taken as the point where a recognizable response is noted within a measured time level hence also termed as an auditory threshold.

Some studies have shown the prevalence of loss in hearing as advancement in age takes place. However, there are few researches that have documented the trend in the hearing loss as age advances. Earlier research was restricted to only a small sample and particular age group of older individuals.

Literature review

The leading research regarding sample sizes on loss progression in a bit older adults was carried out in the framework of Epidemiology of Hearing Loss (Niskar 2001). Progression of Loss in hearing is described as a change which is bigger than five decibels in the frequencies of 0.5, 1, 2, and 4 kHz (pure-tone average). This report, therefore, seeks to cover the specific changes in thresholds as frequencies change at given audiometric frequencies.

A study done by Gates and Cooper in hearing thresholds in a six-year period with a sample size of one thousand four hundred and seventy-five utilized the Framingham group. The individuals in this study were between ages of fifty-eight to eighty-eight at initial stages a thirty-year gap after a six year follow up the program. According to this research, changes were greater at frequencies below 2 kHz for both men and women. Large absolute changes were experienced at higher frequencies. Women had a large change I threshold frequencies as compared to their male counterparts across all frequencies, but at 0.5 kHz, the changes were significant for both genders. At 4.0 and 6.0 kHz, the rate of change in hearing decreased for men but increased for women. At 8.0 kHz, these rates went lower for the older age group for both genders. According to Gates and Cooper (1990), the rate of change in the hearing threshold were at an all-time high between frequencies of six and eight kilohertz (Gates 1990).

Baltimore Longitudinal Study of Aging also documents the evidence in a continuous loss in hearing in a population consisting of mostly aged individuals. The progression of hearing loss was defined as a change which is bigger than five decibels in the frequencies values of 500, 1000, 2000, and 4000 hertz. The report by Cruickshanks et al. failed to take into consideration the certain thresholds and accompanying the variations in the hearing across several age groups putting in mind various audiometric frequencies.

The research was done by, Brant and Foard used a sample size of eight hundred and thirteen individuals and conducted the research within a period of fifteen years. The age gap was between 20 to 95 years, and only the male gender was considered. It was worth to note that at a frequency of 8.0 kHz, the rate of hearing loss remained constant. There report was somehow different from that posted by Gates and Cooper which purported a greater change in loss of hearing between the frequencies of 6 and 8 kHz.

Contrary to the earlier studies, Lee and his colleagues were able to establish variation in pure-tone thresholds for a sample size of one hundred and eighty-eight individuals, 60-81 years in a time gap of three to eleven years. At higher frequencies, Lee and the team observed a faster change in the hearing thresholds. They also established a relationship with the rate of change of hearing threshold between higher frequencies and low frequencies of 0.25 – 2 kHz.

The above studies were restricted in the demographic distribution, and the number of some of the individuals in the higher age group was limited.

Objectives

To find out the change in hearing threshold with increase in age

To establish the difference in change in hearing levels between men and women of different age groups

Method

Participants

Choosing individuals for this study has to be in line with earlier findings of Epidemiology of loss in hearing based on the work done by Cruickshanks (1998). The participants were between the ages of 50 years to 90 years.

Procedure

The air-conduction thresholds for behavior was first derived from both the right and the left ear at audiometric frequencies of 0.250 to 8.0 kHz.by use of the diagnostic audiometer that measured the hearing levels at varying frequencies.

The air-conduction threshold was then duplicated for the same frequencies at baseline for 2.5, 5 and ten-year evaluations. Conduction through the bone was carried out at frequencies of 0.5 and 4 kHz. The audiometer was calibrated I line with the American National Standards Institute (ANSI) standards. Rooms for testing had to be first sound treated so as to exclude any sound of ambient noise between the frequencies of 0.5 through to 8 kHz. Due to some difficulties in achieving a room frequency of 0.25 kHz, a minimum frequency of 0.5 kHz which is easily attainable was therefore used.

The longitudinal changes in the hearing level are computed at frequencies of 500, 1000, 2000 and 4000 hertz. These frequencies were settled upon since they represent the acute energy in speech. The longitudinal changes are therefore calculated from the change in hearing level as from the second visit after each following visit (Cruickshanks 1998).

Cruickshanks suggested that to examine cross-sectional differences in the hearing levels, the hearing levels of the participants during the last visit was used. It is assumed that any change in the levels of hearing is consistent with the normal distribution curves.

Results and discussion

Figure 2: Hearing threshold based on baseline frequencies of 0.5, 1, and 2 kHz.

The figure above represents takes into account thresholds for both the right and the left ear. The slope of the curve is steeper for higher frequencies. This graph shows an increase in the hearing threshold with age and the slope being steeper as age advances and an increase in frequencies. After the age of eighty years, the change in thresholds goes down for the higher frequencies that are 6 and 8 kHz. The findings of Cruickshank’s et al. (1998), show consistency with the longitudinal change in the hearing threshold as illustrated by the above graph.

Figure 2: Increase in the hearing threshold for ten years for both women and men.

Figure 2 shows plots for both women and men’s right and left ear.it is clear observed that the threshold frequencies increase across all ages and frequencies. For the older participants, a dramatic slow in the change of threshold is observed at higher frequencies than at lower frequencies. For younger participants, the reverse was true. At higher frequencies, the change in threshold was higher than the change in frequencies at lower frequencies. Greater loss of hearing at baseline for higher frequencies best explains this alternating trend.

A small range of change at higher frequencies and older adults exhibited a percentage change of 80% in the threshold between frequencies of 6 and 8 kHz. For the longitudinal change in hearing, the level of variation in hearing for males aged thirty years is very minimal. 40, 50, 60, and 70-year-old men showed a small change in the hearing level for a follow up at all frequencies. The lowest frequency of 0.5 kHz, the percentiles became widely distributed for sixty-year-old male participants, at 1 kHz, the percentile was wide distributed for 70-year-old men, at 2 kHz, and the spreading out of percentiles was slight for the 50, 60, and 70 age groups. At a frequency of 4000 Hz, the percentiles were spread out for the 50 and 60-year-old individuals. At frequencies of 1.0, 2.0, and 4.0 kHz, there was an observable drastic decline in the hearing level for the oldest participants.

For women, a unique characteristic is evident, at 1000 hertz and 60-year-old participants, there was a change in the mean longitudinal change in hearing and the spread of the percentiles, however, kept on decreasing over time. This same characteristic is also evident at a frequency of 0.5 kHz for sixty-year-old women. The mean hearing level at this same stage however increases. At 2000 hertz for 50 and a 60-year-old female, the change in the hearing level is not significant even in the subsequent follow-up ears.

For cross-sectional change in hearing, the value of the hearing level during the last visit of the longitudinal visit is used to assess it (Brant 1990). Plotting the graphs will show that there exists no difference between the men and women, but this gap widens with an increase in age.

At frequencies of 500 and 1000 hertz, both women and men showed similar cross-sectional hearing levels. The hearing levels in men participants’ first decrease at a constant rate while for women fist show gradual decline trend followed by an acceleration in the decline of hearing levels as the age increases. Men, however, have higher percentiles than women at a higher age. Both men and women also show the same trend for the 2000 and 4000-hertz frequencies in the change in hearing levels. After that, the levels of hearing in men decline at a constant rate.

Conclusion

The above research has constructed various percentiles in a change in hearing levels at both longitudinal and cross-sectional distribution. A sample population was first examined for any defectives in the ear condition such as the ear drum and the membrane before being considered for the experiment. The curves obtained by plotting the different hearing levels are used to determine whether a certain age group of people exhibit any abnormalities in hearing sensitivities. This is achieved by utilizing the cross-sectional percentiles obtained from the values of longitudinal change in hearing levels.

Once an initial hearing level has been determined, any change in the hearing level is detected by using longitudinal percentile curves that indicate abnormalities in shifts of the hearing level. From the experiment conducted, the data obtained should be compared directly with that obtained by utilizing self-tracking techniques due to accuracy difference between self-recording and the manual recording technique i.e. use of audiometer to measure hearing levels.

The findings are therefore in line with the hypothesis in that the proportion of participants exhibiting a change in the level of hearing increases with increase in age in men while for women the proportion constantly maintains at low levels.

Also according to this experiment is, there is a continuous decline in the hearing thresholds as the age increases. The hearing loss is frequent to the older people because of the deterioration of the hearing capability of the auditory organs. For the age between 50 and 60 years, the changes in the threshold were significant at higher frequencies, and there was less hearing loss for lower frequencies. For the case of the older participants, there is an increase in hearing loss which shows that they experience several difficulties in understanding speech and therefore they require audio logic gadgets to aid in hearing process.

The hearing loss for the younger people is by slight decibels. The young people have a wide hearing range than the older people. In other terms the young people are sensitive to the hearing sense than older people. The degree of vibration of the auditory membranes and the sensitivity of the auditory nerves determine the hearing of an individual as described by the research.

References

Brant, L. J., & Fozard, J. L. (1990). Age changes in pure‐tone hearing thresholds in a longitudinal study of normal human aging. The Journal of the Acoustical Society of America, 88(2), 813-820.

Cruickshanks, K. J., Wiley, T. L., Tweed, T. S., Klein, B. E., Klein, R., Mares-Perlman, J. A., & Nondahl, D. M. (1998). Prevalence of hearing the loss in older adults in Beaver Dam, Wisconsin the epidemiology of hearing loss study. American journal of epidemiology, 148(9), 879-886.

Gates, G. A., Cooper Jr, J. C., Kannel, W. B., & Miller, N. J. (1990). Hearing in the Elderly: The Framingham Cohort, 1983-1985: Part 1. Basic Audiometric Test Results. Ear and Hearing, 11(4), 247-256.

Niskar, A. S., Kieszak, S. M., Holmes, A. E., Esteban, E., Rubin, C., & Brody, D. J. (2001). Estimated prevalence of noise-induced hearing threshold shifts among children 6 to 19 years of age: the Third National Health and Nutrition Examination Survey, 1988–1994, United States. Pediatrics, 108(1), 40-43.