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.
Data for night 1 (without direct contact) are shown in the upper panel, data for nights 2–4 (with direct contact) in the lower panel. The vertical line is drawn at 45 kHz and separates low-frequency and high-frequency syllables.
