The behavior of a sound wave is affected by the density of the medium, the temperature of the medium and the pressure of the medium if it is a gas. Motion of the medium independent of the sound wave may also affect the way sound propagates.
Yes, you may check-in for your Delta Air Lines (DL) flight with your mobile device starting 24 hours and ending 60 minutes before the scheduled departure time (depending on your departure city and destination) to receive a mobile boarding pass on your mobile device.
Prior to one hour before your flight departure time, simply enter your confirmation number, credit card number, or ticket number to successfully check in and avoid the wait. If you are a Delta Frequent Flyer member, check with Expedia.com to see if you earn points with your flight bookings, hotel reservations, or car rentals. Expedia.com offers a variety of rewards, so enter your Frequent Flyer number and program name to see if your bookings are eligible for mileage. Check in with the Delta flight status to receive the most current updates on flight arrivals and departures. This tool provides the latest on your specific flight, including arrival and departure times.