Deer Whistle

Their manufacturers promote them as "acoustic attention-getter", alleging deer would react to the whistle by remaining still.

Evidence Based Study

In 1997 a study conducted by Dr. Ken Risenhoover at Texas A&M University, set out to define the hearing range of the whitetail deer. Using anesthesticized whitetail deer Dr. Risenhoover and his team attempted to define a deer's hearing range by attaching sensors to certain parts of the deer's head and interpreting the electrical responses obtained when sounds at different decibels and frequencies were introduced into the deer's ears. What this study discovered is that, based on the electrical responses, a deer's average hearing range is between 0.5 KHz and 16 KHz depending on the decibel level, with the maximum sensitivity in the 1 to 8 KHz range. That being said how does this hearing range compare to humans? Human Hearing Sensitivity

C.R. Nave with Georgia State University gives a brief synopsis of human hearing sensitivity in a 2005 Hyper Physics Concepts article. In this synopsis it is stated that human hearing sensitivity is rated between .02 KHz to 20 KHz. It can be assumed that these numbers are a fairly accurate representation of the averages found in the human hearing range, because unlike with the deer, a human can provide feedback on what they hear. Human hearing covers a broader range than that of a deer, therefore if you cannot hear the sound from the deer whistle the deer most certainly cannot.