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.
Open symbols indicate responses at 10 dB above pure-tone threshold, and filled symbols 40 dB above pure-tone threshold. Unit types as indicated in key in A. A, C and D, data from all tMTFs (low-pass and band-pass). B, data from band-pass tMTFs only.
