Adventitious Deafness as an Increasing or Decreasing Phenomenon
Our main interest in the problem of adventitious deafness lies in the possible discovery whether or not it is relatively increasing or decreasing among the population, and in what respects signs appear of a diminution. We have just seen the likelihood of a decrease from certain causes; but we are to find what is indicated by statistical evidence.
To be considered first is adventitious deafness as a whole. Respecting it our only statistics are in the returns of the censuses since 1880, the different forms of deafness not being distinguished before this time. The following table will show the number of the adventitiously deaf as reported by the censuses of 1880, 1890 and 1900, with their respective percentages and ratios per million of population.[31]
NUMBER OF THE ADVENTITIOUSLY DEAF IN 1880, 1890 AND 1900
| Total Number | Adventitiously Deaf | Percentage | Ratio per Million of Population | |
| 1880 | 33,878 | 10,187 | 30.1 | 20.3 |
| 1890 | 40,562 | 16,767 | 41.1 | 26.8 |
| 1900 | 37,426 | 18,164 | 48.4 | 23.9 |
From this it appears that adventitious deafness is increasing in relation to total deafness, which is most likely the case, as congenital deafness, as we shall see, is evidently decreasing. Whether or not adventitious deafness is increasing in respect to the general population, the table does not disclose definitely. The statistics probably are not full enough to afford any real indication yet.
Our next inquiry is in respect to the increase or decrease of adventitious deafness from the several diseases individually, which is, upon the whole, the more satisfactory test. Here also, unfortunately, our statistics are very limited, and our findings will have to fall much short of what could be desired.
The following table, based on the returns of the censuses of 1880, 1890 and 1900, so far as the approximate identity of the several diseases can be established, will give the respective percentages found.[32]