Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
| A-weighting | C-weighting | |
|---|---|---|
| IEC 61672-1 Class 1 | 35 kHz | 35 kHz |
| IEC 61672-1 Class 2 | 20 kHz | 20 kHz |
| ANSI S.1-43 Type 0 | 71 kHz | 72 kHz |
| ANSI S.1-43 Type 1 | 35 kHz | 35 kHz |
| ANSI S.1-43 Type 2 | 20 kHz | 20 kHz |
