# Risk Factors for Distortion Product Otoacoustic Emissions in Young Adults
## Results  
### Self-Reported Volume Use and DPOAEs  
Some PM system use characteristics are shown in Table 2. Over half of the participants listening between 1 and 7 h/week and approximately \(\frac{3}{4}\) reported a single longest use per day up to 1 h. The percentages between women and men for these use characteristics were similar. Few participants reported tinnitus after using their PM system, although more women reported tinnitus than men. The percent for self-reported volume categories for all participants and women and men are also shown in Table 2.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **ALL (_n = 216_)** & **WOMEN (_n = 161_)** & **MEN (_n = 55_)** \\ \hline Self-reported PM system use 1 & & & \\ Light (\(\leq\)1 h/wk) & 30 (14.3\%) & 24 (15.4\%) & 6 (11.1\%) \\ Moderate (1–7 h/wk) & 123 (58.6\%) & 95 (60.9\%) & 28 (51.9\%) \\ Heavy (>7 h/wk) & 57 (27.1\%) & 37 (23.7\%) & 20 (37.0\%) \\ Longest single use during a typical day 1 & & & \\ \(<\)1 h & 93 (44.3\%) & 73 (46.8\%) & 20 (37.0\%) \\
1 h & 63 (30.0\%) & 44 (28.2\%) & 19 (35.2\%) \\
2 h & 38 (18.1\%) & 29 (18.6\%) & 9 (16.7\%) \\
3 h & 15 (7.1\%) & 10 (6.4\%) & 5 (9.3\%) \\
4 h & 1 (0.5\%) & 0 (0.0\%) & 1 (1.8\%) \\ Volume use 1 & & & \\ Low/medium volume & 136 (65.1\%) & 110 (70.5\%) & 26 (49.1\%) \\ Loud/very loud volume & 73 (34.9\%) & 46 (29.5\%) & 27 (50.9\%) \\ Hear people 2 & & & \\ Easily hear/have a little trouble hearing people & 158 (75.2\%) & 121 (77.6\%) & 37 (68.5\%) \\ Have a lot of trouble/cannot hear people & 52 (24.8\%) & 35 (22.4\%) & 17 (31.5\%) \\ Report tinnitus after PM system use 1 & & & \\ Yes & 27 (12.9\%) & 23 (14.7\%) & 4 (7.4\%) \\ Preferred listening level L\({}_{\text{Aeq}}\) (dB) & & & \\ Mean (SD) & 73.0 (10.7) & 71.8 (10.7) & 76.5 (10.1) \\ Minimum, maximum & 49.4, 97.5 & 49.4, 97.5 & 49.6, 93.1 \\ Drinks per month (DPM) & & & \\ Non–drinkers & 61 (28.2\%) & 44 (27.3\%) & 17 (30.9\%) \\ Light drinkers (\(\leq\)14 drinks) & 78 (36.1\%) & 60 (37.3\%) & 18 (32.7\%) \\ Heavy drinkers (>14 drinks) & 77 (35.7\%) & 57 (35.4\%) & 20 (36.4\%) \\ \hline \hline \end{tabular}
\end{table}
Table 2: The number, and percentages of participants who reported listening to a PM system at Low/medium volume and Loud/very loud volume and who reported number of drinks per month are shown. The means, standard deviations, minimums, and maximums for preferred listening level are also presented. These data are further separated for women and men.  
Over 50% of men reported using a loud or very loud volume setting with a PM system with earphones, while just under 30% of women reported those same volume settings. Over 30% of men reported having a lot of trouble hearing people or not being able to hear people when using a PM system with earphones, which is slightly higher than the 22.4% of women who reported those same difficulties. After adjusting for test ear and age, there was a statistically significant Sex-by-Loud-by-Frequency interaction (F[16,1024] = 2.22, \(p<0.05\)) for DPOAEs, so sex-specific ANOVAs were performed. For women only, there was no statistically significant Loud-by-Frequency interaction for DPOAEs (F[5,769] = 0.80, \(p>0.05\)) nor a statistically significant main effect for Loud (F[1,769] = 0.12, \(p>0.05\)). Figure 1a shows the means and standard deviations for DPOAEs across the collapsed frequencies and the considerable overlap in the Non-Loud and Loud women. For men only, however, there was a statistically significant Loud-by-Frequency interaction (F[5,255] = 2.93, \(p<0.05\)) and this is shown in Figure 1b where men in the Loud category have poorer mean DPOAEs at 1.5, 2, and 3 kHz.  
The results for the Hear variable were similar such that there was a statistically significant Sex-by-Hear-by-Frequency interaction for DPOAEs (F[16,1029] = 4.20, \(p<0.05\)). For men only again, there was a statistically significant Loud-by-Frequency interaction (F[5,260] = 6.75, \(p<0.05\)) where men who reported having a lot of trouble hearing people or cannot hear people had poorer mean DPOAEs at 1.5, 2, and 3 kHz.