While data varies on ear plug style, this is mainly a chart on a material's effectiviness.
+-------------------+-----+--------------------------------+------+------+------+------+------+------+------+------+
| Ear plug material | NRR |          Frequency (HZ):   125 |  250 |  500 | 1000 | 2000 | 3150 | 4000 | 6300 | 8000 |
+-------------------+-----+--------------------------------+------+------+------+------+------+------+------+------+
| Soft Silicone     |  21 |     Mean Attenuation dB:  25.1 | 24.0 | 22.3 | 26.5 | 36.0 | 41.0 | 40.8 | 40.3 | 40.3 |
|                   |     | Standard Attenuation dB:   3.8 |  3.5 |  3.0 |  3.1 |  3.5 |  3.8 |  3.8 |  3.3 |  3.0 |
+-------------------+-----+-------------------------+------+------+------+------+------+------+------+------+------+
| Soft Wax          |  24 |                         | 23.0 | 24.5 | 25.6 | 30.1 | 35.6 | 40.8 | 40.0 | 39.0 | 40.0 |
|                   |     |                         |  3.2 |  3.0 |  3.0 |  1.8 |  2.4 |  1.7 |  2.6 |  3.3 |  4.0 |
+-------------------+-----+-------------------------+------+------+------+------+------+------+------+------+------+
| Soft Foam         |  33 |                         | 33.1 | 36.3 | 36.8 | 38.4 | 38.7 | 44.1 | 44.1 | 45.4 | 46.0 |
|                   |     |                         |  2.7 |  1.8 |  2.1 |  1.7 |  2.1 |  2.3 |  2.3 |  2.2 |  2.4 |
+-------------------+-----+-------------------------+------+------+------+------+------+------+------+------+------+
| Low Pressure      |  30 |                         | 33.5 | 33.6 | 36.0 | 37.5 | 39.4 | 42.5 | 42.5 | 43.7 | 45.2 |
|                   |     |                         |  3.6 |  3.4 |  3.2 |  3.5 |  3.5 |  3.4 |  3.4 |  4.8 |  5.1 |
+-------------------+-----+-------------------------+------+------+------+------+------+------+------+------+------+

All according to ANSI Standard S 3.19 (1974)

Log in or registerto write something here or to contact authors.