Table 1. Reference Equivalent Threshold Sound Pressure Levels for Circumaural Headphones.

ANSI S3.6 2010
Frequency	Sennheiser HDA200 and RadioEar DD450
125	30.5
250	18
500	11
750	6
1,000	5.5
1,500	5.5
2,000	4.5
3,000	2.5
4,000	9.5
5,000	14
6,000	17
8,000	17.5
9,000	19
10,000	22
11,200	23
12,500	27.5
14,000	35
16,000	56
Speech	19

Notes: These values are added to the audiometer dial setting to convert HL to SPL. ANSI S3.6 2010 Specifications for audiometers.